Sotalia fluviatilis

INFORMATION AND CHARACTERISTICS.

The unique name of this cetacean is pronounced “tucushi” and comes from the Tupi language, typical of South America. It is also known as gray bufeo and black bufeo in the area.

This little-known species is physically similar to the bottlenose dolphin (Tursiops truncatus) except for its size and other minor details. It is found in fresh and salty waters but is not genetically related to the South American river dolphins. Described initially in 1853, the Tucuxi is a small dolphin.

Order: Cetacea
Family: Delphinidae
Genus: Sotalia

The author of the image: Archilider.

HOW DO THEY LOOK? PHYSICAL CHARACTERISTICS.

Morphology.
The shape of its body is similar to that of the bottlenose dolphin as it is fusiform and slightly robust. It has a triangular dorsal fin slightly hooked. Its snout is long, very pronounced and narrow. Its pectoral flippers are large.

Weight and size.
It is one of the smallest cetaceans of the Delphinidae family, and there is no presence of sexual dimorphism. Adults have an average length of 2.1-2.2 meters and a weight of 35 to 55 kilograms. Individuals living in freshwater have a shorter length, estimated at 1.5 meters.

Skin Coloration.
The color of its dorsal skin varies being either bluish, gray or dark brown. The lower part of its body is white, light gray or pink and the sides are a shade between the dorsal and ventral colors. It has a dark strip blended between the snout and each of the pectoral flippers. Some populations have yellow stripes on the sides and a clear spot on the dorsal fin.

Distinctive characteristics.
Most specimens have a white patch on the tip of the snout.
There are two ecotypes of this species, one living in ocean waters of the Atlantic Ocean and another dwelling in the Amazon and Orinoco Rivers.

WHERE DO THEY LIVE? DISTRIBUTION AND HABITAT.

The Tucuxi is a species endemic to South American waters; the tucuxi inhabits waters of Brazil, Panama, Peru, Ecuador, Colombia, Nicaragua, Venezuela and probably Honduras. Its distribution range starts from this last country or Panama and runs along the east South American coasts ending in southern Brazil.

There are two ecotypes of this species, one living in the waters of the Atlantic Ocean and other that dwells in the Amazon and Orinoco rivers. Those who live in the ocean stay near the coasts, in estuaries, and bays. The freshwater ecotype, inhabit the channels of the rivers mentioned above reaching upriver up to 2,500 kilometers in the Amazon and 250 kilometers in the Orinoco.

WHAT DO THEY EAT? DIET AND EATING HABITS.

The tucuxi is a carnivorous dolphin. It submerges for about 30 seconds to search for food, and they frequent the confluence areas because it is a zone suitable for the development of species such as plankton which in turn attracts many species of fish. Therefore, this dolphin usually goes to the confluences of bodies of water, but it also goes to places near the coasts.

Ray-finned fishes (Actinopterygii class), octopuses, squids, and shrimps are the main part of its diet. If they are in the open ocean, they prefer to feed on small fishes grouped in schools, and near the coasts, they prefer to catch pelagic or demersal fishes and cephalopods.

The tucuxi living in the Amazon consume around 28 species of fish, and within this set, they prefer those that belong to the family Curimatidae, because they represent 52 percent of their total diet.

HOW DO THEY BEHAVE? BEHAVIOR

It is considered a shy dolphin which never get close to boats or people and whose swimming is slow, but this does not mean that is “not active.” On the contrary, it spends most of the day doing activities, and its leaps out of the water are impressive. It can leap up to 1 meter out of the water and executes jumps, tumbles and blows with its pectoral flippers and the tail either alone or in coordination with other members of its pod. The only thing they do not do is riding the bow waves of boats, which is evident, as they do not come close to them.

This dolphin has a social structure based on small groups containing 2 to 6 members. In most cases, the pod is made up of 9-20 individuals for the ecotype living in freshwater and up to 50 members for those dwelling in the coastal waters of the Atlantic. Occasionally the pods associate with other species of dolphins, such as the Amazon pink dolphin (Inia geoffrensis). In any case, it seems that the adult males dominate the pods and they are the ones followed by other members.

The flood season is perfect for swimming through small tributaries, but they do not dare to leave the main river channels and enter into flooded forests. On the other hand, they communicate through whistles and clicks. Their sounds are higher than those of other dolphins, and they produce them while feeding, perhaps to call their peers.

HOW DO THEY REPRODUCE? MATING AND REPRODUCTION.

Researchers believe that the females of this species mate with several males in the same breeding period (polyandry). The courtship includes an aggressive behavior of males.

Both genders reach sexual maturity at six years of age. The gestation period lasts between ten and twelve months, and the calf is born at some point in the autumn. The offspring can have a length from 71 to 106 centimeters.

WHAT IS THEIR CONSERVATION STATUS? THREATS AND CONSERVATION.

Conservation status: Data Deficient.

The tucuxi has a conservation status of “Data Deficient” in the Red List of the International Union for the Conservation of Nature (IUCN). The size of the total population is unknown, but it is true that it is vulnerable to the effects of human activities such as:

– Bycatch.
– Direct hunting.
– Prey Overfishing.
– Habitat Contamination.
– Acoustic pollution.
– Boat collisions.
– Construction of dams that reduce and segment their distribution.

This dolphin is in Appendix II of the CMS (Convention on Migratory Species) for animals in need of conservation agreements and in Appendix I of CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora), which contains species with a higher danger of extinction and whose trade is prohibited. Also, the International Whaling Commission (IWC) initiated a plan called Project Sotalia with the aim of studying this species thoroughly.

References

http://www.iucnredlist.org/details/190871/0

William F. Perrin, Bernd Würsig, J.G.M. ‘Hans’ Thewissen. Encyclopedia of Marine Mammals. Academic Press, 2009. Page 1188.

http://animaldiversity.org/accounts/Sotalia_fluviatilis/

http://www.arkive.org/tucuxi-dolphin/sotalia-fluviatilis/

INFORMATION AND CHARACTERISTICS.

Delphinus delphis is probably one of the most common species of dolphin, and it has a broad distribution around the world. The naturalist Carlos Linnaeus was the first person to describe this short-beaked cetacean in 1758. It is probably the most abundant dolphin on the ocean.

Order: Cetacea
Family: Delphinidae
Genre: Delphinus

HOW DO THEY LOOK? PHYSICAL CHARACTERISTICS.

It is a medium-sized dolphin, similar to other common dolphin species.

Weight and size.
The sexual dimorphism is slight since males are larger and heavier than females. The average length is 1.52-1.82 meters, and the weight is 100-136 kilograms.

Morphology.
Its fusiform body has a long snout (even though is shorter than that of the Delphinus capensis) and a rounded melon. The Short-beaked common dolphin has a dorsal fin almost triangular, with a curved inclination. The pectoral flippers and the flukes of their caudal fin are small.

Skin Coloration.
Its coloring pattern features a dark dorsal area and a white ventral region. From the end of the beak starts a layer of dark color that extends toward the dorsal fin and the sides, forming a “V.” From the lower jaw to the flippers, there is a narrow black stripe, and a dark patch is around the eyes. Along the sides, there is a thick band of light color that does not become white.

Distinctive characteristics.
The shape of the coloring pattern is its most distinctive sign. To distinguish it from Delphinus capensis, which is very similar, the size of the beak is the main feature that makes them different.

> Short-beaked common dolphin characteristics.
> Short-beaked common dolphin – Delphinus delphis.

WHERE DO THEY LIVE? DISTRIBUTION AND HABITAT.

This dolphin inhabits all tropical, subtropical and warm seas of the world, especially in the Pacific and Atlantic oceans. In the south of Australia. In the western Atlantic it extends from Newfoundland to Florida in the United States; From Norway to West Africa in the eastern Atlantic, from Canada to Chile in the eastern Pacific Ocean; In the central region of this ocean and around New Caledonia, New Zealand and Tasmania. It has a presence in a few closed seas: the Sea of ​​Japan, the Sea of ​​Ojotsk (Asia) and the Black Sea.

It inhabits coastal areas or the high sea as long as the water temperature is 10 to 28° Celsius. It dwells along the continental slope, in waters with depths ranging from 200 to 2,000 meters and has a preference for the marine areas where the upwelling occurs and for the seamounts and escarpments.

WHAT DO THEY EAT? DIET AND EATING HABITS.

Small fish such as herring, sardines, hake, and anchovy are an important part of their diet, also cephalopods which include octopus and squid. They consume crustaceans to a lesser extent. In total, an adult dolphin consumes more than 8 kilograms of food per day.

It feeds mostly at night, and it has cooperative hunting strategies. When a group of dolphins is looking for food, each member submerges for up to 8 minutes to detect prey. If they are successful and find a school of fish or any other prey, they can perform two hunting strategies:

1.- Individually, these dolphins approach the center of the school of fish and chase them. Before the prey escapes, they catch it.

2.- Dolphins dive towards a school of fish chasing them to guide them towards the surface of the water. They prefer to feed at night because they wait for the prey that migrates to the surface every night.

The whole hunting process takes about 1 hour, and they can submerge up to 200 meters deep during the process.

HOW DO THEY BEHAVE? BEHAVIOR

It is very rare to find a Short-beaked common dolphin alone. These dolphins are very social which can be seen in all their daily activities like eating, traveling and even breathing. The pods are very numerous and are composed of 10 to 500 individuals but, as in other species, they usually associate with other pods forming large temporal groups of thousands of dolphins. Its association with other species of cetaceans like the pilot whales (Genus Globicephala) is also common.

This species is a perfect example of a playful dolphin. It jumps, hits the water with its flippers, and spin in the air for several hours. Without a doubt, their favorite game is to ride the bow waves of boats. Its swimming speed reaches up to 60 kilometers per hour.

Short-beaked common dolphin – Delphinus delphis.

It shows great empathy for its peers. When a member of the pod is sick or injured, another dolphin helps him to float and breathe, a fact that demonstrates their capacity for bonding. This dolphin can remember its mates even though it has been a long time since they separated and experiences joy and excitement. In the same way, if one dies or separates, it shows sadness.

Individuals in some regions migrate seasonally in a process induced by the temperature increase of the surface water.

HOW DO THEY REPRODUCE? MATING AND REPRODUCTION.

An unusual fact about the reproduction of this dolphin is that, although it is usual to have only one offspring, there are some cases of births with 2 and up to 3 dolphins, when in other species this happens much less frequently.

Males reach sexual maturity between 12 and 15 years of age, but females are mature when they reach 85 percent of their final size and if they have ovulated at least once in their lifetime. But the sexual maturity and the interval of births vary considerably among populations since in some parts these dolphins reach maturity at 2.7 years; In the eastern Pacific Ocean females give birth every three years, but in the Black Sea they can do it every year.

Their sexual habits are not only for reproduction. They can participate in activities that provide pleasure for themselves or their peers. During spring and autumn, males begin to courtship females with actions involving physical contact and approach, then both mate. Females have a gestation period of 10-12 months.

From the moment of its birth, the offspring is of vital importance for the mother and the pod; It swims next to its mother and separates just a few feet from it as it grows. Weaning occurs when offspring are between 5 and 19 months of age.

WHAT IS THEIR CONSERVATION STATUS? THREATS AND CONSERVATION.

Conservation Status: “Least Concern.”

By-catch with longlines, gillnets, and trawls constitutes the greatest threat to the survival of this species. In Asia and areas of the Mediterranean Sea, is hunted for human consumption to prepare some little-known dishes, but also for its oil. Additionally, the chemical contamination and the human disturbance of their habitat are also important factors, although fortunately the species still has a conservation status of “Least Concern” on the Red List of the International Union for Conservation of Nature.

The species has the safeguard of the Marine Mammal Protection Act of 1972. In the United Kingdom, killing cetaceans is banned by the law. Seven European countries signed the Agreement on the Conservation of Small Cetaceans in the Baltic, North East Atlantic, Irish and North Seas (ASCOBANS). Also, there are plans to create protected areas for this dolphin and to control the pollution of its habitat.

References

William F. Perrin, Bernd Würsig, J.G.M. ‘Hans’ Thewissen. Encyclopedia of Marine Mammals. Academic Press, 2009. Page 255.

Mammals in the Seas: Small cetaceans, seals, sirenians and otters. Food & Agriculture Org., 1978.

http://www.cms.int/reports/small_cetaceans/data/d_delphis/d_delphis.htm

http://www.iucnredlist.org/details/6336/0

Feresa attenuata

INFORMATION AND CHARACTERISTICS.

The pygmy killer whale despite its name, is not closely related to the orca (Orcinus orca), the so-called “killer whale,” but it has similar features which gave it this name. The naturalist John Gray described this species in 1874, but previously in 1827, the report of another scientist included it. Despite these works, scientists did not take much notice of this dolphin, which remained almost unknown for many years.

This situation changed in 1954 when a Japanese cetacean scientist Munesato Yamada published his observations based on parts of the body of a specimen. This researcher also proposed the name “pygmy killer whale” for the species.

Order: Cetacea
Family: Delphinidae
Genus: Feresa

HOW DO THEY LOOK? PHYSICAL CHARACTERISTICS.

Morphology.
The pygmy killer whale has a thin body, a rounded head, and a narrow tail. It lacks the long snout that many people associate with dolphins. Its dorsal fin is high and curved at the tip just like its pectoral flippers. The lower jaw has 20-26 teeth while the upper jaw has only 16-24.

Weight and size.
Adults have a length of 2.1-2.6 meters and weigh about 170-225 kilograms.

Skin Coloration.
Its dorsal skin is dark gray, the ventral region is white, and on the sides the black blend with a light gray layer. Its lips are white.

Distinctive characteristics.
The curvature of its dorsal fin, its gray skin, white lips and the lack of a pronounced snout are the features that make the pygmy killer whale different from other species.

WHERE DO THEY LIVE? DISTRIBUTION AND HABITAT.

The distribution of the pygmy killer whale includes the tropical and subtropical waters of the Pacific Ocean, Atlantic Ocean and the Indian Ocean between latitudes 40° north and 35° south. Encounters with this species are extremely rare and are less than 1 percent of the total sightings of toothed cetaceans. Nevertheless, there are more sightings in the eastern tropical Pacific and the southern Atlantic Ocean than everywhere else.

To the north, it reaches the latitude of the Bay of Biscay, and to the south, it reaches the tip of the African continent.

It likes to inhabit waters with up to 500 meters deep with warm temperatures above 18° Celsius. It rarely approaches the coasts, and when it does, usually approximates volcanic islands.

WHAT DO THEY EAT? DIET AND EATING HABITS.

According to remains found in the stomachs of some specimens of pygmy orcas, it is a carnivorous and predatory dolphin that feeds on several species of fish, cephalopods and even small cetaceans. Its main foods are octopus, squid (Families Onychoteuthidae and Ommastrephidae), sardines (Family Clupeidae) when it remains in captivity.

It probably looks for food at night and consumes slightly large prey for its size because its teeth are also relatively large.

HOW DO THEY BEHAVE? BEHAVIOR.

Like many other dolphins, it is a species that likes playing. It frequently jumps out of the water, strikes its pectoral flippers against the water, pulls its body out of the water and even hit the surface of the ocean with the head. However, it is perhaps a dolphin less active than other dolphins since it has been seen resting on the surface in the company of other pygmy killer whales, all forming a group swimming in the same direction.

It is a highly social species that creates small groups. The pods have about 12-50 members but occasionally form groups of hundreds of individuals. It is a species very aggressive when kept in captivity.

HOW DO THEY REPRODUCE? MATING AND REPRODUCTION.

There isn’t much information about the reproduction of the pygmy killer whale. The researchers think that they reach sexual maturity according to its length, that is, when males reach more than 2.16 meters and when females exceed 2.21 meters. In other regions, this cetacean reach maturity with a length of 2.31 meters, however, the age at which this occurs is entirely unknown.

The other known data on the reproduction of the pygmy killer whale is about the birth of the single offspring. The length of the calf is around 0.8 meters, but more studies and observations are needed to support this data and get conclusive information.

WHAT IS THEIR CONSERVATION STATUS? THREATS AND CONSERVATION.

Condition: “Data defficient”.

As expected for a little known and understudied species, the Red List of the International Union for the Conservation of Nature classifies the Pygmy killer whale as “Data deficient.”

However, it is a species highly vulnerable to loud noises and perhaps to climate change. In Indonesia, Japan, Sri Lanka and areas of the Caribbean, it is the subject of direct fishing for human consumption of meat and oil. Particularly in Sri Lanka, fishers use parts of its body as bait for sharks and other species of fish.

In specimens off the coast of Florida, United States, scientists found traces of hydrocarbons in their body tissues as the result of water pollution that affects the cetacean.

At present, there are no specific strategies focused on the conservation of the pygmy killer whales. However, it is in Appendix II of CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora), in other words, it is a species that Although not in great danger of extinction, its trade must be strictly regulated.

References

http://www.iucnredlist.org/details/8551/0

http://www.nmfs.noaa.gov/pr/species/mammals/cetaceans/pygmykillerwhale.htm

William F. Perrin, Bernd Würsig, J.G.M. ‘Hans’ Thewissen. Encyclopedia of Marine Mammals. Academic Press, 2009. Page 938.

http://www.fao.org/fishery/species/18192/en

Lagenorhynchus australis

INFORMATION AND CHARACTERISTICS.

The Peale’s dolphin or Black-chinned Dolphin are the common names used to call this toothed cetacean of the southern hemisphere. In English, its common name, Peale’s dolphin is in honor to the naturalist Titian Peale, who described the species in the year 1848.

It is the largest species of the genus Lagenorhynchus, although in recent years a closer relationship with the genus Cephalorhynchus was discovered, which could end in a new taxonomic classification for this species shortly.

Order: Cetacea
Family: Delphinidae
Genus: Lagenorhynchus

HOW DO THEY LOOK? PHYSICAL CHARACTERISTICS.

Morphology.
It is perhaps the most robust species of its genus but still conserves a body with a form of a torpedo. Its dorsal fin, pointed and curved, can reach up to 50 centimeters of height and its rounded pectoral flippers measure around 30 centimeters in length. It has a short beak; it is only about 5 cm long.

Weight and size.
There is a slight sexual dimorphism that produces greater dimensions in the case of males. An adult measures 2.18-2.20 meters in length while the females reach about 2.10 meters in length. The maximum size of an adult is 3.10 meters. They weight on average 115 kilograms.

Skin Coloration.
The color of its skin is remarkable and very striking. Black on the dorsum and white on the belly, this two-color pattern is interrupted by a thin white stripe that begins below the dorsal fin and widens as it extends backward. From the eyes to the middle of the sides there is a white area separated from the belly by a thin black band. The pectoral flippers and the dorsal fin are black.

Distinctive characteristics.
It is true that this species can easily be confused with the Dusky dolphin (Lagenorhynchus obscurus), but this dolphin has a dark face and a thin black band near the rib cage which makes it different.

WHERE DO THEY LIVE? DISTRIBUTION AND HABITAT.

This animal is endemic of the southern hemisphere, and they dwell between latitudes 30° south in the Pacific and 38° south in the Atlantic Ocean and 60° south where both oceans join, that is, in South American waters surrounding the southern tip of the continent. This distribution includes only Chile, Argentina, and the Falkland Islands; Around Tierra del Fuego, Cape Horn and the Strait of Magellan. Recently sightings of the species were reported near the Cook Islands, between Hawaii and New Zealand but this is unconfirmed data yet.

It is a coastal dolphin that inhabits seas with very shallow depths on the continental shelf. It dwells in the bays, inlets, canals, fjords and stay around the islands, on beds of seaweed and even on the sandbanks.

WHAT DO THEY EAT? DIET AND EATING HABITS.

The Peale’s dolphin does not mind feeding alone but usually hunts in groups. It has a carnivorous diet and eats large quantities of fish as well as crustaceans and cephalopods. The prey most consumed by this species are:

– Argentine red shrimp (Pleoticus muelleri).
– Squids of the species Loligo gahi and Illex argentinus.
– Argentine Hake (Merluccius hubbsi).
– Tadpole codling (Salilota australis).
– Patagonian grenadier (Macruronus magellanicus).
– Southern red octopus (Enteroctopus megalocyathus).
– Anchovy (Family Engraulidae).
– Herring (Genus Clupea).

It has a very varied diet. The feeding process begins with the formation of groups of 5 to 30 individuals who stay underwater for 10 seconds-1.5 minutes. They have a marked preference for searching algae beds. When they find prey, they surround it and begin to eat. If the victims are a school of fish, they spend time chasing, corraling and eating them in organized turns.

HOW DO THEY REPRODUCE? MATING AND REPRODUCTION.

The information about their reproductive habits is very scarce. What is known is that the female has one offspring per delivery and gives birth during the spring to autumn after a gestation period of 10 to 12 months.

When births are close, the mothers approach to areas close to the coast. There a calf is born with a length of approximately 0.9-1.25 meters, which swims next to its mother as soon as it leaves the belly. The offspring is cared for about 18 months or until it is two years old.

HOW DO THEY BEHAVE? BEHAVIOR

The pods of Peale’s dolphins have few members, between 2 and 20 individuals although there are groups as small as 2-4 or as large as 100 dolphins. These large groups, if created, are in turn segmented into smaller social clusters. They usually hunt by cooperation, but a hypothesis assumes that this happens only when there is abundant food.

They occasionally associate with other species of dolphins, especially the Commerson’s dolphin (Cephalorhynchus commersonii) and the Risso’s dolphin (Grampus griseus).

It is a shy dolphin that sometimes comes close to the boats but not often. From there you can see it jumping, riding the bow waves and splashing water with its tail.

No migration patterns are known, but southernmost individuals are believed to follow fish movements.

WHAT IS THEIR CONSERVATION STATUS? THREATS AND CONSERVATION.

Conservation Status: “Data Deficient.”

The Red List of the International Union for the Conservation of Nature does not have sufficient data to assess this species according to its state of conservation. However, since the 1970s it has been exploited to use parts of its body as bait for crabs and is not free of the danger that gillnets mean.

In addition to direct and incidental catch, contamination of their habitat with organochlorines endangers their health, as well as tourist rides that offer dolphin observations can disrupt their life underwater.

The Peale’s dolphin is in Appendix II of CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora), where the species whose trade requires strict regulation appear. Also, the Chilean government has implemented measures to reduce the use of dolphin meat as a crab bait, and because of this, it seems that the number of catches for this purpose has reduced.

References

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.452.3889&rep=rep1&type=pdf

http://www.iucnredlist.org/details/11143/0

https://en.wikipedia.org/wiki/Peale%27s_dolphin

http://www.cms.int/reports/small_cetaceans/data/L_australis/L_australis.htm

http://www.arkive.org/peales-dolphin/lagenorhynchus-australis/

INFORMATION AND CHARACTERISTICS.

The Northern right whale dolphin and its close relative the southern right whale dolphin (Lissodelphis peronii), are the only dolphin species of the family Lissodelphis that lack a dorsal fin. The naturalist Titian Peale was the first to describe this species in 1848. Its scientific name comes from word Lissos that means “soft” in Greek, and the Latin borealis which means “north.”

HOW DO THEY LOOK? PHYSICAL CHARACTERISTICS.

Morphology.
The slender, hydrodynamic body of the northern right whale dolphin allows it to reach great speed when swimming. Both species of the genus Lissodelphis are the thinnest of all the small cetaceans, and this, in particular, is endowed with a short “snout” and a tilted forehead, both separated by a fold. It has no dorsal fin but has two small, curved and pointed pectoral flippers.

Order: Cetacea
Family: Delphinidae
Genus: Lissodelphis

Weight and size.
Usually, males are larger and heavier than females. An adult male individual measures approximately 3.1 meters in length but the range of the female is 2.3-2.6 meters. The weight oscillates between 60 and 100 kilograms.

Skin Coloration.
The shining dolphin’s skin has a dark color on the dorsal area that contrasts with the white belly, however, this is little visible. Under the lower jaw, it has a white spot. Both the pectoral flippers and the caudal fin are black.

Distinctive characteristics.
It is easy to distinguish this dolphin from other species, but it can be confused with sea lions because of the lack of dorsal fin. It is necessary to observe the dorsum and the coloring pattern characterized by black and white to avoid confusion with other animals.

WHERE DO THEY LIVE? DISTRIBUTION AND HABITAT.

The Northern right whale dolphin has a limited distribution. It is found only in temperate and cold waters of the North Pacific Ocean between latitudes 30° and 50° north. They inhabit from northern Baja California in Mexico to the Gulf of Alaska, and in the west from Kamchatka in Russia to Japan. It is present in Russia, Mexico, the United States, Canada, and Japan.

It inhabits waters of the platform and the continental slope of great depth as well as (occasionally) areas near the coasts as long as they are deep. The temperature of its habitat is generally below 19° C but can tolerate those equal to or less than 24° C.

WHAT DO THEY EAT? DIET AND EATING HABITS.

Fish and cephalopods make up most of the diet of this carnivorous dolphin. It feeds on a wide variety of species. Some of its favorite prey are:

– Lanternfish (myctophids).
– Hake.
– Saury (family Scomberesocidae).
– Octopus.
– Squid.

When they inhabit around the center of the Pacific Ocean, the lanternfish make up the prey most consumed by this dolphin.

HOW DO THEY BEHAVE? BEHAVIOR.

The Northern right whale dolphin is very gregarious and creates pods quite large. They are comprised of 100-200 dolphins although the most common number is 200. However, sometimes they form superpods up to 2,000-3,000 individuals. The organization of such pods is somehow similar to some birds; they can travel forming a V.

It often associates with other dolphins and marine mammals, especially the Pacific white-sided dolphin (Lagenorhynchus obliquidens) and the Risso dolphin (Grampus griseus). It swims very fast, and its average speed is about 25 kilometers per hour, but it has speed bursts up to 40 kilometers per hour.

Sometimes the pod creates disturbance in the surface of the water due to its acrobatics, jumps, splashes with the tail and belly. It is also a little nervous and if something disturbs it, then flees immediately.

There are reports of seasonal migrations triggered by changes in water temperature. During spring and summer, the southernmost individuals travel to the north, and the northern ones migrate south.

HOW DO THEY REPRODUCE? MATING AND REPRODUCTION.

Data on the reproductive habits of this cetacean are very scarce. They reach sexual maturity between 9.7 and 9.9 years of age, being the later in males. In the winter-early spring period, there is more birth frequency, but other researchers believe that most births occur during the summer months, between July and August.

The female gives birth every 2 or more years to one offspring whose length is 0.8-1 meter.

WHAT IS THEIR CONSERVATION STATUS? THREATS AND CONSERVATION.

Conservation Status: “Least Concern.”

The conservation state of this dolphin is “Least Concern” on the Red List of the International Union for the Conservation of Nature (IUCN). A few years ago thousands of Northern right whale dolphins (Lissodelphis borealis) were killed annually in waters of Japan, Korea, and Taiwan as result of bycatch. Today, the number of deaths has reduced, but gillnets, direct harpoon hunting and contamination of its habitat still threaten the survival of this dolphin.

Efforts to preserve this dolphin involve its inclusion in Appendix II of CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) and taking the measures recommended by the Pacific Offshore Cetacean Take Reduction Team of the National Marine Fisheries Service (NMFS) to reduce incidental fishing mortality.

References

Annalisa Berta. Whales, Dolphins, and Porpoises: A Natural History and Species Guide. University of Chicago Press, 2015.

http://www.iucnredlist.org/details/12125/0

http://www.nmfs.noaa.gov/pr/species/mammals/cetaceans/northernrightwhaledolphin.htm

INFORMATION AND CHARACTERISTICS.

It is one of the two species of common dolphins that belong to the genus Delphinus. Therefore it has a similar appearance to the short-beaked common dolphin (Delphinus delphis), and they were considered part of the same species until the mid-1990s when they were separated and recognized Delphinus capensis as a different species.

Its scientific name comes from the place where it was found in the 19th century, in 1828: the Cape of Good Hope. There are two subspecies of Long-beaked common dolphins, Delphinus capensis capensis and Delphinus capensis tropicalis.

Order: Cetacea
Family: Delphinidae
Genus: Delphinus

HOW DO THEY LOOK? PHYSICAL CHARACTERISTICS.

If a person is on the high seas, it ‘s hard to distinguish this species from Delphinus delphis, but the former dolphin has a longer and thinner snout than the latter.

Weight and size.
It is a medium-sized dolphin with a length estimated between 1.9 and 2.5 meters being the males slightly larger than the females. In average, individuals can weight between 80 and 235 kilograms but usually not more than 150 kilos.

Morphology.
The shape of its body is fusiform but robust. In the center of the dorsum, it has a curved dorsal fin. Its head is less rounded than other species since the melon rises from the snout at a small angle.

Skin Coloration.
It has a coloring pattern that extends from the sides of the body to the dorsal fin. The upper area is dark, the lower is white, and both pectoral flippers have the same dark color of the top. The dark color can be dark gray or dark brown, while the light color can be white or light yellow.

WHERE DO THEY LIVE? DISTRIBUTION AND HABITAT.

The Long-beaked common dolphin inhabits specific areas of the Atlantic, Indian and Pacific Oceans. It is possible to find it from the west coast of the United States to Baja California in Mexico. There are also populations in Mexico, Peru, Chile, Venezuela, Brazil, Argentina, West Africa, South Africa, Madagascar, the Arabian Peninsula, India, Indonesia, China, South Korea and southern Japan.

The subspecies Delphinus capensis capensis dwells on the east coast of South America, western Africa, southern Japan, Korea, northern Taiwan, South Africa, and California in the United States to Peru. Delphinus capensis tropicalis lives in the Indo-Pacific up to the Gulf of Thailand.

The Long-beaked common dolphin typically prefers temperate water habitats about 180 kilometers away from the coasts on the continental shelf, at lower depths than Delphinus delphis. It does not usually congregate around the oceanic islands and do not inhabit the high seas.

WHAT DO THEY EAT? DIET AND EATING HABITS.

The Long-beaked common dolphin has a carnivorous diet abundant in small fish, cephalopods, and crustaceans. In the north of the Gulf of California, this dolphin gathers with others of the same species forming pods of tens to thousands of individuals, and cooperate to catch prey. What they do is chasing and herding large schools of fish, and when they become disoriented, they keep the school together to expedite its consumption.

The above involves submerging at about 280 meters deep for a maximum of 8 minutes before surfacing to get oxygen. Their hunting and feeding activities occur near the coasts, in shallow waters. Some of its habitual prey are:

– Sardines and Herrings (Family Clupeidae).
– Anchovies (Genus Anchoa).
– Hakes and Cod (Order Gadiformes).
– Squid (Order Teuthida).
– Krill (Order Euphausiacea).

Although group hunting is well-known in the Gulf of California, most think that something similar happens in other regions where this dolphin lives.

HOW DO THEY REPRODUCE? MATING AND REPRODUCTION.

The Long-beaked common dolphin reaches sexual maturity when the specimen exceeds 2 meters in length, but the age at which it occurs varies according to the geographic region in which the dolphin lives. In males can happen between 2 and seven years and in females between 3 and 12 years.

Mothers give birth every 2 or 3 years. After mating, usually during the spring and autumn months, females have a gestation period of 9-11 months after which one single offspring is born with a weight of approximately 10 kilograms and a length of 0.8-1.0 meters as well as a coloration less dark than that of adults. The mother weans the baby about six months after birth.

It is interesting to know that captive individuals of this species have successfully mated with bottlenose dolphins, resulting in hybrid offspring capable of reproducing. This species lives in the wild about 22 years.

HOW DO THEY BEHAVE? BEHAVIOR

Delphinus capensis is one of the most gregarious animals in existence, and its pods are made up of hundreds or thousands of individuals that may organize into smaller groups of about 10-30 members according to age and gender. Sometimes they swim along with other cetaceans such as pilot whales (Globicephala).

These dolphins are socially active, very energetic and even curious as they approach the boats and stay close to them for a long time. They are fast swimmers and perform various types of acrobatics, among them, riding the bow waves of boats and jumping out of the water; They also whistle with their heads out of the water.

WHAT IS THEIR CONSERVATION STATUS? THREATS AND CONSERVATION.

Conservation Status: “Data Deficient.”

This species has a conservation status as “Data Deficient” in the Red List of the International Union for the Conservation of Nature (IUCN). It is sometimes intentionally hunted (sometimes harpooned) in Japan, northern Venezuela, areas of the Caribbean, Peru, and West Africa to get their meat for human consumption or as bait. Other direct catches are to get them for aquariums or parks.

Bycatch is probably the greatest threat to their survival. In China, Southern California and other parts of the tropical eastern Pacific, it is frequent their entanglement in gillnets, driftnets, and trawl nets.

On the other hand, pollution also threatens their survival. According to researchers, they found remains of organochlorines in their fat.

The good part of this scenario is that the species is under the protection of the Marine Mammal Protection Act of 1972, which applies measures that prevent dolphin degradation.

References

William F. Perrin, Bernd Würsig, J.G.M. ‘Hans’ Thewissen. Encyclopedia of Marine Mammals. Academic Press, 2009. Page 255.

http://www.cms.int/reports/small_cetaceans/data/d_capensis/d_capensis.htm

http://www.fisheries.noaa.gov/pr/species/mammals/dolphins/common-dolphin_long-beaked.html

https://en.wikipedia.org/wiki/Short-beaked_common_dolphin

Lagenorhynchus cruciger

INFORMATION AND CHARACTERISTICS.

The world of toothed cetaceans is very vast. It contains large species, small species, unusual animals and beloved animals. The hourglass dolphin is one of the lesser-known dolphins, but it is an interesting one.

The hourglass dolphin is a cetacean rarely seen but described for the first time in 1824 from a drawing made in 1820. By 2010, only six complete specimens and parts of bodies from stranded dolphins had been in research labs. Some people call them by the nickname of “marine cow” because of the similarity of its coloration with the terrestrial cows.

Order: Cetacea
Family: Delphinidae
Genus: Lagenorhynchus

HOW DO THEY LOOK? PHYSICAL CHARACTERISTICS.

Morphology.
The hourglass dolphin has a small, sturdy, plump-looking body. Its dorsal fin is large and curved backward and moderately high while its pectoral fins are broad and hooked in the case of individuals who have recently reached sexual maturity.

Weight and size.
The records of the dolphin’s dimensions are still inconclusive, but they suggest that males may be larger than females. The length of adults is on average 1.8 meters and their weight 90-120 kilograms.

Skin Coloration.
The skin of the dolphin is black and white. The coloring pattern of its skin looks like an hourglass, so from this comes its colloquial name: Hourglass dolphin. The dorsal area is entirely black, but the color is interrupted on the sides of the body, which have a white patch that starts at the head, narrows near the dorsal fin, continues backward and ends near the tail. Under this white part, there is a black band that reaches the pectoral flippers and the caudal fin. The ventral area is white, and the beak is black.

Distinctive characteristics.
The hourglass dolphin is easy to identify because of its unique hourglass-shaped pattern.

WHERE DO THEY LIVE? DISTRIBUTION AND HABITAT.

This species inhabits southern waters between the latitudes 45° south to 68° south, frequently near the Antarctic convergence. In fact, it is has a circumpolar distribution in the Antarctic region between South America and the Macquarie Island and around the province of Tierra del Fuego. The furthest sighting, in the north, occurred near Chile.

Their habitats are remote to humans. They typically dwell in deep waters and temperatures between -0.3 ° and 13° Celsius. They rarely come to the coasts and occasionally visit shallow waters.

WHAT DO THEY EAT? DIET AND EATING HABITS.

Fish, crustaceans, and cephalopods make up the Lagenorhynchus cruciger diet. If it consumes fish, it prefers lanternfish (myctophids) mainly the species Krefftichtys andersonii. If they consume squid, their favorites are those of the Onychoteuthidae and Enoploteuthidae families. Observations indicate that they like to approach plankton concentrations and partner with seabirds.

It uses its sense of echolocation to detect prey. To do it, these dolphins emit acuter sounds than those of other species of dolphins, especially clicks, so that they can find prey from farther distances.

HOW DO THEY BEHAVE? BEHAVIOR

It is a social dolphin although its pods have few members: usually, they do not exceed 6 or 8 members, still sometimes they form groups of about 60 individuals. It associates with other cetaceans such as the fin whale (Balaenoptera physalus), the Minke whale (Balaenoptera acutorostrata) and the Southern bottlenose whale (Planifrons Hyperoodon).

The hourglass dolphin swims at a speed of 22 kilometers per hour and is an energetic acrobat of the seas. It is very curious and is not afraid to approach boats, that is why they usually ride the bow waves of boats and jump out of the water enthusiastically.

During the summer months, it is frequent to see hourglass dolphins in the waters of the south. Therefore it probably makes seasonal migrations following the cold currents.

HOW DO THEY REPRODUCE? MATING AND REPRODUCTION.

Based on the reproductive processes of other species closely related to the hourglass dolphin and some observations, information about their breeding habits is known.

The age at which they reach sexual maturity is still unknown. Most births occur between August and October, the months corresponding to the Antarctic winter. The gestation period is about 12-18 months, and at birth, the calf is approximately 90-125 centimeters long.
Breastfeeding can last up to 2 or 2 ½ years, as in other dolphins.

WHAT IS THEIR CONSERVATION STATUS? THREATS AND CONSERVATION.

Conservation Status: “Least Concern.”

It is one of the few species of cetaceans that is not vulnerable because of human activities, and this is thanks to the location of its habitat far from civilization. However, their biggest anthropogenic threat could be global warming.

It is likely that the populations of this dolphin are almost intact since they have never been under a systematic hunting as most cetacean species.

For some conservation organizations, this panorama does not mean that they do not need protection, therefore CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) has included it in Appendix II of species whose trade must be under supervision. Their conservation status in the Red List of the International Union for the Conservation of Nature is “Least Concern.”

References

http://www.arkive.org/hourglass-dolphin/lagenorhynchus-cruciger/

http://www.iucnredlist.org/details/11144/0

http://www.cms.int/reports/small_cetaceans/data/L_cruciger/L_cruciger.htm

https://en.wikipedia.org/wiki/Hourglass_dolphin

INFORMATION AND CHARACTERISTICS.

The Guiana dolphin (Sotalia Guianensis) is a small South American dolphin which is often confused with the Tucuxi (Sotalia fluviatilis). In fact, these two species were recently taxonomically separated because they are two genetically different species. The data collected on this species is still quite limited given the recent change of its taxonomy, so the information is not comprehensive. It is also known as the estuarine dolphin.

Order: Cetacea
Family: Delphinidae
Genus: Sotalia

HOW DO THEY LOOK? PHYSICAL DESCRIPTION.

Morphology.
It is a species with an appearance similar to the familiar bottlenose dolphin (Tursiops truncatus) but smaller. Also, it is almost identical to the Tucuxi (Sotalia fluviatilis), and they are easily confused where their distribution range overlaps. However, the Guiana dolphin is approximately 30% larger than the Tucuxi.

It has a narrow and pronounced “snout,” very defined and with a medium size. Its curved dorsal fin is small and has a triangular shape and a rounded tip.

Weight and size.
Despite the similarities, its size is smaller than that of the bottlenose dolphin mentioned above but is larger than its closest relative, the tucuxi (Sotalia fluviatilis). It reaches 2.1-2.2 meters in length and an average weight of 60 kilograms.

Coloring.
It has a countershading with blue or gray on the dorsal area and white, light gray or even pink in the ventral region. The dorsal fin has the same dark color of such part, but the flippers are darker than the vicinity with a darker color similar to that of the dorsal part.

Distinctive marks.
Between the flippers and the dorsal fin, this dolphin has an area of light skin. Besides this and the size differences, it is somewhat difficult to distinguish it from the two species mentioned above.

WHERE DO THEY LIVE? DISTRIBUTION AND HABITAT.

The Guiana dolphin inhabits the waters of eastern South America and Central America, from northern Nicaragua to the state of Santa Catarina in southern Brazil. It is, therefore, present in the western Atlantic Ocean including some regions of the Caribbean Sea, the Amazon River, and its tributaries. In this regard, there are two ecotypes: one in the Amazon basin and another exclusively marine.

It inhabits coastal waters, bays, estuaries and shallow areas of the river and its tributaries as well as its delta, as long as the water is shallow.

WHAT DO THEY EAT? FEEDING.

The carnivorous diet of this dolphin includes a vast diversity of fish species, but it also consumes squids and crabs. Part of its diet incorporates fish of the family Sciaenidae and the species Largehead hairtail (Trichurus Lepturus), Sardinella brasiliensis, Pellona barroweri, Harengula clupeola; Shrimp Penaeus schmitii and cephalopods of the species Lolliguncula brevis.

The Guiana dolphin is intelligent. It observes the habits and social structure of the fish (mainly of those that form schools) and uses its behavior to capture them and feed on them. Their method of hunting is creating a cooperative group, which once they detect a school of fish, they follow it, surround it and then take turns to feed while others keep the school compact and controlled.

HOW DO THEY BEHAVE? BEHAVIOR.

It is a highly sociable species but creates small pods. The number of individuals in a pod usually ranges from 10 to 15, but occasionally there are groups up to 20 or 30 members. In some areas of Brazil, they swim in groups of 2 to 10 individuals. In fact, the size of the pods varies depending on the area where they live in, the activity they perform and even the time of the day.

The Guiana dolphins do not usually approach the boats because they are a bit shy. What they usually do is perform stunning acrobatics, ride the bow waves of boats, jump out of the water and hit the water with its tail and flippers. Therefore, most observations are made from far which makes research difficult as well as knowing more about their behavior.

HOW DO THEY REPRODUCE? REPRODUCTION.

Observations indicate that this dolphin reproduces every two years using a polygamous system. Sotalia guianensis reach sexual maturity between five and eight years of age, but females mature before males.

The gestation period lasts about 12 months, after which the female gives birth to 1 offspring with a length of 0.7-0.9 meters.

As all dolphin species, the mothers take care of their calves for a long time until they reach a size and age to defend themselves from predators.

THREATS AND CONSERVATION.
WHAT IS THEIR CONSERVATION STATUS?

The Guiana dolphin faces the constant threat of purse seiners and fishing gillnets where they get trapped or entangled and die. In several regions of South America, hundreds of these dolphins die every year due to bycatch. To give an example, just in the Amazon delta, about 2,000 Guiana dolphins die each year, and in other areas, people directly hunt they for human consumption.

About 2,000 Guiana dolphins die annually just in the Amazonas River delta.

Additionally, collisions with ships and vessels due to the high traffic in some areas of its distribution range, the degradation of their habitat because of pollution or coastal development and the disturbance as a result of human activities as industry and tourism complete the list of anthropogenic threats.

In the wild, it is predated by killer whales and sharks.

Conservation Status: “Data Deficient.”

The Red List of the International Union for Conservation of Nature (IUCN) does not have enough data to evaluate its conservation status, so it has a classification as “Data Deficient.” However, the CMS (Convention on the Conservation of Migratory Species of Wild Animals) has included the Guiana dolphin in Appendix II of species with an unfavorable conservation status.

References

http://www.iucnredlist.org/details/181359/0

http://rspb.royalsocietypublishing.org/content/early/2011/07/21/rspb.2011.1127?sid_=35f01848-638a-4256-bab8-b75325534842

http://onlinelibrary.wiley.com/doi/10.1111/j.1748-7692.2007.00110.x/full

https://en.wikipedia.org/wiki/Guiana_dolphin

INFORMATION AND CHARACTERISTICS.

The false killer whale is the third largest dolphin in the world. A skeleton of this species discovered in 1843 in England was at that time the most preserved fossil of a cetacean. Owen was the first naturalist to describe it in the year 1846 and was named Phocaena crassidens. Incredibly, the fake orca was seen alive 15 years after the discovery of its skeleton.

While its current common name refers to the orca (Orcinus orca), this species and Pseudorca crassidens do not belong to the same genus and are not closely related. However, both species have similar features like the shape of the skull and the morphology of the dental pieces.

Order: Cetacea
Family: Delphinidae
Genus: Pseudorca

HOW DO THEY LOOK? PHYSICAL CHARACTERISTICS.

Morphology.
The shape of its body is fusiform. Slender and hydrodynamic, the false killer whale has a conical head which is devoid of a snout. Their narrow, pointed pectoral flippers have a sort of lump in the middle, so they look like elbows.

Weight and size.
The maximum length of females is approximately 5.1 meters while the largest males can measure up to 6.1 meters. Female weigh about 1,200 kilograms while males have a weight of up to 2,200 kg.

Skin Coloration.
The skin on its body is black or dark gray except for the whitish chest, and the faint light gray spots sprinkled around the neck and the head.

Distinctive characteristics.
Its elbow-shaped pectoral fins are the perfect feature to distinguish this dolphin quickly and easily from other species. The lack of snout and the almost full black color are also some unique features.

WHERE DO THEY LIVE? DISTRIBUTION AND HABITAT.

It is possible to find false killer whales in tropical and subtropical waters of the Pacific Ocean, the Atlantic Ocean, and the Indian Ocean. Its boundaries are latitude 50° north and 52° south, so it has a wide distribution in saltwater systems, including seas and semi-closed places such as bays.

In the south, it extends from New Zealand to Chile, Australia, Peru, South Africa, Argentina and even the United States, the Bay of Biscay, the Red Sea, the Mediterranean Sea, the Sea of ​​Japan, and British Columbia. Although there are no reports of populations living in countries close to the North Pole, sightings include places like Norway and Alaska, but they are probably lost individuals because they are not cold water residents.

It has a particular preference for waters with depths of approximately 2,000 meters. It rarely approaches the coasts, and when it does, it prefers to stay close to the oceanic islands and sometimes ventures into seas or closed water systems.

WHAT DO THEY EAT? DIET AND EATING HABITS.

To hunt, a pod of 300 individuals can travel in a straight line spanning an area of ​​5 km.

The false killer whale is a carnivorous animal, but its prey is not only fish; it also includes crustaceans and cephalopods. Its size allows this dolphin to hunt some species of marine mammals successfully.

This kind of victim is common in waters of the eastern Pacific, where they have been seen attacking humpback whales calves (Megaptera novaeangliae). The following are just some of the preys that are part of its usual diet:

Yellowfin tuna (Thunnus albacares).
Albacore o longfin tuna (Thunnus alalunga)
Swordfish (Xiphias gladius).
Pacific bonito (Sarda lineolata).
Mahi-Mahi (Coryphaena hippurus).
Salmon (Genus Oncorhynchus).
Yellow Corvina (Larimichthys polyactis).
Wahoo (Acanthocybium solandri).
Japanese seabass (Lateolabrax japonicus)
Atlantic Mackerel (Scomber scombrus)
Herring (Genus Clupea)
Squid (Several species)

Sea lions (Subfamily otariinae) and probably young individuals or offspring of other dolphin species, humpback whales and sperm whales (Physeter macrocephalus).

It feeds opportunistically in coordinated groups. To hunt, a pod of 300 individuals can travel in a straight line spanning an area of ​​about 5 kilometers. It usually captures a prey near the surface, shaking it violently until dismembering it and eliminates the skin before consuming it. An interesting detail: the false killer whales share their food with their pod companions and mothers allow their offspring to feed on the prey that are inside their mouths.

HOW DO THEY BEHAVE? BEHAVIOR

This cetacean presents a very evident gregarious behavior, and they establish close ties between them. However, their pods are made up of relatively few members, about 10-50 in general, but in some regions, the groups may be more or less numerous, reaching up to 100 individuals. When they swim together, some subdivisions within the group are visible.

Social relations are long and stable throughout their life, with a minimum duration of 15 years. In Scotland, Ceylon, Zanzibar and Great Britain, numerous strandings of these cetaceans have taken place to the point of counting 800 stranded individuals in dramatic cases. It is also a species that usually stays within a particular area. For example, false killer whales in Hawaii do not move more than 500 kilometers around their area.

The false killer whale performs some acrobatic jumps, including riding the bow waves of the boats and jumping out of the water. On the other hand, this dolphin communicates with its mates through whistles, squeals and pulsating sounds of frequencies above 100-130 kilohertz.

HOW DO THEY REPRODUCE? MATING AND REPRODUCTION.

The false killer whale can mate throughout the year if the individual is already sexually mature. Females reach maturity between 8 and 11 years while males reach maturity at 8 to 10 years of age. Both are polygamous and have a very low reproduction rate because mothers have offspring only every seven years.

Mating occurs when a male detects receptivity of a female. If there is not conception in the first ovulation, the female keeps the ovulation until it is pregnant.

The gestation period lasts 11-12 months, and after that time the calf is born with a length of about 2 meters. The mother feeds the offspring for 18-24 months, after which it can consume solid foods.

WHAT IS THEIR CONSERVATION STATUS? THREATS AND CONSERVATION.

Conservation status: Data Deficient.

Bycatch (mainly in Japan and Indonesia), reduction of prey availability, pollution of coastal waters and killing by fishers who consider it a competitor for fish, put this cetacean on a bad conservation perspective.

The number of individuals that exist is not known, in fact, the Red List of the International Union for Conservation of Nature does not have enough data to evaluate their conservation status.

Their inclusion in Appendix II of CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) implies a better regulation for this species.

References

http://www.iucnredlist.org/details/18596/0

http://www.nmfs.noaa.gov/pr/species/mammals/cetaceans/falsekillerwhale.htm

William F. Perrin, Bernd Würsig, J.G.M. ‘Hans’ Thewissen. Encyclopedia of Marine Mammals. Academic Press, 2009. Page 405.

Gerardo Ceballos. Mammals of Mexico. JHU Press, Oct 9, 2014

Striped Dolphin

(Stenella coeruleoalba)

INFORMATION AND CHARACTERISTICS.

The striped dolphin is among the most studied members of the Delphinidae family and is very abundant in the oceans. In 1833, the botanist Franz Meyen described the species and named it Delphinus Coeruleoalbus from the study of a specimen from Rio de la Plata.

Order: Cetacea
Family: Delphinidae
Genus: Stenella

HOW DO THEY LOOK? PHYSICAL CHARACTERISTICS.

There is a slight variation in the body of the populations of the striped dolphin, but it is only in the shape of the skeleton and not the external appearance.

Morphology.
Its fusiform body is robust but able to perform graceful movements. It has a narrow, long and prominent snout, a rounded forehead because of the pronounced melon, long and narrow pectoral flippers and a curved dorsal fin located in the center of the dorsal area.

Weight and size.
It is a medium-sized dolphin. The adult male has a length of 2.6 meters and a weight of 160 kilograms. The female measures up to 2.4 meters and weighs about 150 kg.

Skin Coloration.
The dorsal region is blue or blue-gray, and the lower ventral area is lighter blending from light gray to whitish. There is a pattern of dark stripes extending from the eyes to the flippers and another set that begin near the eyes and end in the anus. On the sides, there is an area of light skin before the start of the caudal fin, but the pectoral flippers are dark.

Distinctive characteristics.
The easiest way to recognize a striped dolphin is observing the coloring pattern of its body.

WHERE DO THEY LIVE? DISTRIBUTION AND HABITAT.

This dolphin inhabits the temperate and tropical waters of the Atlantic, Pacific, and Indian Oceans, the Mediterranean Sea, the Caribbean Sea, the Black Sea and the Gulf of Mexico. Its distribution range is between latitudes 50° north and 50° south. It dwells in waters of the United States, Belize, Mexico, China, Costa Rica, Australia, Brazil, Dominican Republic, Guatemala, India, Indonesia, France, Senegal, Uruguay, Philippines, Sri Lanka, Portugal, Qatar, Greenland, French Polynesia, Mozambique, New Zealand, Barbados, Cuba, Germany and many others.

Its habitats are waters with temperatures ranging from 10° to 26° Celsius degrees but tend to avoid waters that are less than 20° Celsius. Commonly it thrives in areas of upwelling and convergence. It is a dolphin mainly pelagic.

WHAT DO THEY EAT? DIET AND EATING HABITS.

The diet of the striped dolphin is not the same in all the regions where it lives. It is a carnivorous animal that feeds mainly on bony fish, cephalopods, and crustaceans. The prey of this dolphin is small animals, measuring 6 to 30 centimeters in length.

The population of the Mediterranean Sea consumes almost entirely cephalopods, octopus, and squid. Those living off the coasts of Japan and South Africa prefer to eat lanternfish (Myctophidae family), and in the northeastern Atlantic, the diet of striped dolphins is 56 percent cephalopods, 39 percent fish, and 5 percent crustaceans. Again, lanternfish are the favorites of this population, but the cod fish is also appreciated.

It has an opportunistic feeding style and can look for its food in any area of ​​the water column. If necessary, it submerges to depths of 200 to 700 meters. The decomposition of the food found in the stomach of some specimens studied suggests that these dolphins wait for the sunset or the early night to carry out their feeding activities.

HOW DO THEY BEHAVE? BEHAVIOR

The striped dolphin groups in pods of 100 to 500 individuals organized by age, gender and reproduction status. However, sometimes they form larger groups with thousands of dolphins.

The division in the society of these dolphins is in groups of young individuals, adults in breeding age, and non-breeding adults. The association with other species of dolphins or animals is rare.

It is a very active, energetic and extremely agile dolphin. It can jump out of the water, ride the bow waves of boats, spin in the air and perform a particular movement that consists of jumping quickly and turning several times in the air before diving back into the ocean. On the other hand, its capacity of communication is similar to the one of other dolphins, based on the emission of clicks, squeals, and whistles.

The striped dolphin performs some seasonal travels related to warm ocean currents, with differences between populations. For example, the dolphins of the Mediterranean Sea move north as soon as they feel that the temperature of the ocean begins to rise.

HOW DO THEY REPRODUCE? MATING AND REPRODUCTION.

Females reach sexual maturity at the age of five, but this can extend until they reach 13. In the case of the males, sexual maturity occurs between 7 and 15 years.

Mating seasons differ between regions. The dolphins living in the Mediterranean sea commonly mate during the fall; While populations dwelling in the Northwest Pacific breed during the winter months. A female has offspring every four years, but this is only an estimate and may be less or more time.

The gestation period of a striped dolphin lasts between 12 and 13 months, after which a single offspring is born, measuring between 90 and 100 centimeters. Summer and fall are the seasons with more births. The caring mother, nurses its calf for 12 -13 months.

WHAT IS THEIR CONSERVATION STATUS? THREATS AND CONSERVATION.

Conservation Status: Least Concern.

The striped dolphin is the target of some fisheries that seek to get their meat or keep them away from the boats, as the cetacean can approach to “steal” fish. Japan is the country with the largest direct catches, with numbers ranging from 600 to 800. In the Mediterranean Sea, the number of dolphins captured is lower. In this case, they hunt these dolphins for human consumption.

Another threat is bycatch in several parts of the world. The problem is that some fishing is illegal and there are not records of all deaths. In the western Pacific Ocean, the deaths of dolphins trapped are numerous: from 2,000 to 4,000 individuals.

Overfishing, contamination of their habitat and noise pollution complete the range of threats. Nevertheless, it is on the Red List of the International Union for the Conservation of Nature (IUCN) as “Least Concern.”

In the United Kingdom, the striped dolphin is under the protection of the UK Biodiversity Action Plan and the Wildlife and Countryside Act of 1981. Also, it is in the Agreement on the Conservation of Small Cetaceans in the Baltic, North East Atlantic, Irish and North Seas (ASCOBANS).

References

http://www.iucnredlist.org/details/20731/0

http://www.cms.int/reports/small_cetaceans/data/S_ceoruleoalba/s_coeruleoalba.htm

Jefferson, Webber, Pitman. Marine Mammals of the World: A Comprehensive Guide to Their Identification. Academic Press, 2015. Page 261.

http://www.fao.org/fishery/species/3596/en

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