Bottlenose dolphins are present in most oceans and seas of the world and adapt quickly to several types of habitat.

Their thermoregulation capacity allows them to live in waters ranging from 10 to 32 degrees Celsius, which includes temperate, tropical and subtropical areas of the Pacific, Atlantic, Indian Ocean, as well as the Mediterranean Sea and the Black Sea between Europe and Asia. The regions that avoid are the polar zones, but some individuals move through the north of Europe, whose waters have low temperatures.

In the Pacific, their distribution range is from northern Japan to Australia and from southern California to Chile in the eastern Pacific Ocean including all the vast area in the middle.

In the Atlantic ocean, they dwell from Nova Scotia to Patagonia in the West and from Norway to South Africa in the East including all the eastern coast of the United States, and the Gulf of Mexico.

Bottlenose dolphin habitat includes bays, open waters, coastal areas, lagoons, estuaries, tidal areas and shallow areas. They even venture occasionally into some rivers.

The other bottlenose species, the Indo-Pacific bottlenose dolphin, is also distributed in tropical and subtropical areas in specific regions of the ocean. This dolphin inhabits from western South Africa to Japan, including eastern and western Australia and places such as the Red Sea, Persian Gulf, Solomon Islands and the Indo-Malay archipelago.

The Indo-Pacific dolphin lives near the coasts of continental shelves, at depths of less than 300 meters and around oceanic islands. It frequently visits estuaries and coral reefs where fish banks thrive, and a significant amount of cephalopods live. Therefore it tolerates salt water and brackish waters.

In the vast ocean, all creatures are vulnerable. Bottlenose dolphins are cetaceans that rarely become prey, thanks to their size, their intelligence, the use of echolocation and their level of socialization that gives them a significant advantage by staying in groups and intimidating their opponent. However, two predators will take the smallest opportunities to feed on dolphins: killer whales and sharks.

We know that the killer whales are expert hunters, especially when they hunt in organized groups. Although there are few documented cases, these animals that are the world’s largest dolphins, attack other species of smaller dolphins, mainly young, newborn or sick. To do it they separate the mother from the calf, making impossible to the latter defend its offspring.

However, a group of orcas does not feel intimidated by a large pod of dolphins. Although there are no records of this kind of attack to bottlenose dolphins, there are videos where a pod of killer whales approaches aggressively to groups of dolphins of other species, and as if they were seals, they beat them and throw them into the air until they are stunned and finally feed on them. Several types of dolphins suffer this kind of aggression, and the bottlenose dolphins are likely part of this list.

Regarding sharks, the most dangerous species for members of the genus Tursiops are the largest: tiger shark, sand shark, bull shark and, of course, the great white shark. It is not uncommon to observe dolphins with scars from shark attacks, which means they are not easy prey and their escape techniques often help them survive.

A study conducted in Shark Bay, Western Australia, revealed that 95 of 128 bottlenose dolphins analyzed showed scars from shark bites, mostly from tiger sharks. The frequency of new body marks and the high attack rates suggest that bottlenose dolphins are at risk in this locality more than in other parts of the world.

A few cases with rays are known. Although they are not dolphin predators because they have a diet based on small fish, mollusks, and plankton, the trauma and infections they cause with the sharp edges of their tail sometimes become deadly.

An ecological niche is a role or way of life that an organism takes within its habitat and how it adapts to meet its basic needs to survive and proliferate, through a set of conditions, resources, and interactions with others.

Two organisms can not have the same niche, as they would compete for the same resources, which would cause only the strongest to survive, leading its opponent to extinction. In nature, although there are some species whose niches overlap, they have different options that make them easier to satisfy their daily requirements.

In this sense, the niche of Orcas is quite variable. The extensive distribution of this species makes that its populations have different cultures that have evolved according to their environment. Some even think that new unidentified subspecies are wandering in the oceans right now.

The niche of these cetaceans differs more clearly in their diet. For example, North Pacific killer whales that live south of Alaska, Washington, and British Columbia and are known as residents rely on fish and squid. In contrast, orcas called transients and whose range of distribution overlaps with residents, but without interbreeding, have a diet that is based primarily on marine mammals.

The interesting thing about killer whales is that they are not limited by salinity, temperature or depth since they have the capacity to move through waters of different latitudes, the open sea or reach coastal areas with depths of only a few meters.

The five ecotypes of Antarctic killer whales and three of Pacific killer whales differ considerably in diet habits, habitat, behavior, and social structure. Therefore their niche entirely depends on the ecotype.

What does this have to do with the dolphins in the wild? Well, thinking that dolphins are non-human people means to consider them beings with rights protected by the laws in a similar way to humans, that is, they must be treated as equals and not as inferiors, which questions their capture and slaughter, as it should be considered murder. In this way, the captivity of dolphins ideally would be reduced.

Ethics as a philosophy prizes the right of people’s freedom and this should be the same in the Animal Kingdom, but it has not been so, and many dolphins have spent their lives, sometimes their whole, living in harsh conditions and without the possibility to experience the freedom of their species.

Life in captivity is not as fun as it seems in dolphinariums.

While even the best aquariums restrain freedom, we have to be aware that not all places that keep dolphins have the best conditions for them. In general, life in captivity is not as fun as it seems in top notch dolphinariums. In fact, there are some differences between dolphins living in those facilities and dolphins in the wild. These discrepancies seem to be always better for free dolphins which make us think that all animals are born free, and although humans use them for various purposes, usually with an ulterior economic end, life in the wild is ideal for them because:

To start with the most evident, free dolphins have hundreds of miles to swim in the ocean, explore and live for a long time. Captive dolphins have ponds or water bodies of several meters, which they can not leave unless their holders decide otherwise, very much like a prison. What about those dolphins that instinctively perform migrations?

Free dolphins born, grow, reproduce and die according to their nature and instincts. Captive dolphins are forced to do several things, for example, they may be induced to mate, to consume a certain food or behave in a particular way.

Free Dolphins retain their physical characteristics unless they are injured, but in captivity, they exhibit an atrophied dorsal fin, that is, it bends downward, perhaps because they spend only 20 percent of their time underwater compared to the 80 percent of the time that free individuals spend.

Normally dolphins have a relatively long life in their natural habitat, but in captivity, both the longevity and the chances of survival reduce. These cetaceans may die during their capture or their transfer as a result of an inadequate supervision of the transport structures or as a result of accidents. In general, captive dolphins live fewer years than their free counterparts.

Dolphins Swimming in the Ocean.

Although dolphins can resist the transportation, their anatomy is not designed to withstand the weight of their body caused by gravity on land. Internal organs or bones like the rib cage can get damaged by carrying them out of the water.

There is no certainty about the proper treatment of captive dolphins unless specific investigations are performed. Therefore, it all depends on the conscious of the people who capture them. While not all are ruthless, we know the where money is involved, some people sacrifice the security and comfort of the dolphins to get higher profits.

Some people argue that in captivity dolphins are safe from predators such as killer whales and sharks, that they have guaranteed food every day and that they have the medical attention of professional veterinarians in case of injury or illness. However, we must not forget that they are animals perfectly adapted to the aquatic life and all that this entails, like the large space in the ocean, the diversity of food and the chance of socializing.

The social life of dolphins and the tight bonds between them is also a major concern for dolphins in captivity as confined they have no contact with other mates or at most with a few of them also in the same conditions.

Conservationists argue strongly about all this, but the release of the captive dolphins is still unlikely.

Humans are a sociable species, we also depend on relations and connections with others to survive, and we all know that most lonely people is not happy and sometimes they have depression and other consequences related to that loneliness. As we are aware, one of the main characteristics of dolphins is their social behavior, so the answer to this is pretty obvious. Dolphins belong to the wild.

WILD DOLPHINS

While the demand for dolphins increases for attractions like swim with dolphins or Dolphin Assisted Therapy (DAT) programs, more and more dolphins are kept in captivity.

Some scientists claim that dolphin research is progressing in great strides, but critics believe that keeping wild dolphins in captivity is cruel and should be stopped.

When contrasting wild dolphins to dolphins in captivity, there are vast differences in behavior, but the high cost of studying wild dolphins has made that scientific data available comes mainly from those in captivity.

Wild dolphins can travel up to 40 miles every day and are constantly on the move, foraging for food, playing and fighting within their pods. Sometimes they submerge to great depths and are hard to follow.

The need for continuous movement of Wild dolphins is one of the reasons that critics of captivity use as arguments to request the release of these dolphins.

The process to capture wild dolphins has traumatic effects on them. Statistics show that 53% of the dolphins that survive the process will die within the first three months.

DOLPHINS IN CAPTIVITY

Regardless that the dolphins we see in captivity seem to be happy, scientists believe that their boredom eventually leads to their premature deaths. Dolphins in captivity, spend only 20% of their time under the surface contrasting with the dolphins in the wild that can be up to 80%.

Activities like beaching themselves in aquatic shows are against their nature because the dolphins in the wild would never beach themselves. Scientists believe that this is extremely harmful because resting on their bellies over a hard surface, will eventually damage their internal organs.

At least 50% of the dolphins in captivity will die in less than seven years. Chlorine poisoning, diseases, and stress-related illnesses are the main reasons that cause the death of those in captivity.

Sometime during the capture process, dolphins are herded towards the shore, separating those still swimming with their mothers from the pod. They are then trussed in a sling and carried from the water to a transport vehicle. Research proves this procedure is very traumatic to dolphins.

US government researchers have found that mortality rates in bottlenose dolphins rise six-fold immediately after capture.

Experience have shown that Dolphins in captivity do not live more than a few years. However, better caring procedures and advanced veterinary medicine, have helped them to live longer, sometimes as long as the dolphins in the wild. Scientists have not figured out yet why dolphins in captivity live less, as most wild animals in captivity, protected from their natural predators will always outlive their counterparts in their natural environments.

Many animal conservation groups are demanding the release of dolphins in captivity, but while there is profit involved, this will be difficult to achieve.

References

Use of Marine Mammals in Swim-with-the-dolphin Programs (FL,HI): Environmental Impact Statement, Volume 1. 1990.

http://us.whales.org/wdc-in-action/end-captivity

http://us.whales.org/faqs/captivity

Janet Mann. Cetacean Societies: Field Studies of Dolphins and Whales. University of Chicago Press, 2000.

(Lagenodelphis hosei)

 INFORMATION AND CHARACTERISTICS.

It is one of the most recently recognized cetaceans. The Fraser’s dolphin was scientifically described for the first time in 1956 Although the first specimen analyzed was in Borneo in 1895. During the first half of the twentieth century, the knowledge about this species came only from some bones until 1971 when scientist rediscovered the species thanks to the sighting of a live specimen in 1970.

The name of this dolphin is in honor of Francis Fraser, its discoverer in 1956.

Order: Cetacea
Family: Delphinidae
Genus: Lagenodelphis

HOW DO THEY LOOK? PHYSICAL CHARACTERISTICS.

This little-known dolphin is a medium-sized cetacean with a very distinctive appearance.

Weight and size.
The adult male is slightly larger than the female, so there is sexual dimorphism in the species. While females reach a maximum length of 2.6 meters, males can reach up to 2.7 meters in length. It weighs about 200 kilograms.

Morphology.
The Fraser’s dolphin body is robust and fusiform, with a postanal hump and a small beak. The pectoral flippers and the flukes of the caudal fin are triangular and pointy. The dorsal fin located in the middle of the dorsum is small, triangular and slightly curved.

Skin Coloration.
The color pattern of its body is unique to this species although it has a stripe that starts in the eyes and ends towards the anus present in other species. This band is very visible in young specimens, and it gets darker when the dolphin is older. It varies according to the habitat and the gender, and is similar to a raccoon “mask.”

The background color of the skin is bluish gray in the upper dorsal area and white or light pink in the lower ventral region.

Distinctive characteristics.
Along the lower jaw begins another light stripe that extends to the sides of the body.

WHERE DO THEY LIVE? DISTRIBUTION AND HABITAT.

It has a pantropical distribution (tropical regions of all the continents). The Fraser’s dolphin dwells between the latitudes 30° north and 30° south in the Pacific, Atlantic, and Indian oceans but it reaches places outside of its range of distribution in Australia, France, Scotland, and Uruguay, perhaps due to climate change.

It is present in Australia, Thailand, China, Brazil, Costa Rica, Dominica, Ecuador, Senegal, Solomon Islands, Cape Verde, Taiwan, Venezuela, Argentina, Angola, Comoros Islands, Japan, Kiribati, Madagascar, South Africa, Spain, Costa Rica, Oman, Palau, French Polynesia, Panama, Micronesia, Philippines, Sri Lanka and Saint Vincent and the Grenadines.

It inhabits tropical and subtropical waters with depths greater than 1,000 meters in areas near the coasts, or areas of the continental shelf.

WHAT DO THEY EAT? DIET AND EATING HABITS.

Their diet is composed of mesopelagic fish, cuttlefish, squid and shrimp. It prefers to feed in deep areas (250-500 meters deep) and very rarely on the surface, so their food can also be benthic. It always looks for the biggest prey available.

HOW DO THEY REPRODUCE? MATING AND REPRODUCTION.

Both genders reach sexual maturity at about seven years of age, but possibly females can be mature a little earlier. This cetacean is polygamous, and the mothers can give birth once every two years.

Mating appears to occur during the summer months. There is no knowledge about possible courtship processes among the couple. The gestation period lasts between 10 and 12.5 months, after which the female gives birth in spring or summer to a single offspring that measures about 1 meter in length.

The life expectancy of this dolphin is approximately 16 or 17 years although in Japan an individual of 17 years and a half was found.

HOW DO THEY BEHAVE? BEHAVIOR.

It is a marine mammal that shows high sociability. The pods of this dolphin are made of 10 to 100 individuals, and sometimes they create larger groups up to 1,000 dolphins. They have no problem in associating with other species of dolphins or cetaceans, such as the melon-headed whale (Peponocephala electra) and the Short-finned pilot whale (Globicephala macrorhynchus). Seagulls can also associate with this dolphin to feed themselves.

The pods move fast, and a single Fraser’s dolphin swims in a manner described as “ostentatious” and “aggressive,” leaving a trail of foam in its wake. Pods seldom follow boats and may be timid and playful although in some areas they prove to be more accessible.

WHAT IS THEIR CONSERVATION STATUS? THREATS AND CONSERVATION.

Conservation Status: “Least Concern.”

This species has a conservation status as “Least Concern” on the Red List of the International Union for the Conservation of Nature (IUCN). However, it continually faces the danger of bycatch. In the eastern Pacific Ocean, this dolphin often gets entangled in nets targeting tuna, but in regions near the Philippines, more than 800 dolphins are captured annually to use their meat or as bait for other species.

This dolphin does not have any known natural predator, but some think that killer whales and sharks can attack them, as in the case of other cetaceans.

Despite the threats, Fraser’s dolphins are still abundant in their range of distribution. There are no specific research or conservation strategies, but the species is in Appendix II of CITES, in the group of species which its commercial fishing requires control.

References

http://www.iucnredlist.org/details/11140/0

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

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

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

]]> https://www.dolphins-world.com/dolphin-habitat-and-distribution/ Tue, 25 Apr 2017 21:13:09 +0000 http://www.dolphins-world.com/?p=48 Dolphins have a worldwide distribution, as they inhabit all the oceans and seas of the world except the Caspian Sea and the Aral Sea. Most species are concentrated in temperate and tropical areas although they dwell from the equator to the subpolar regions.

Obviously, the distribution and habitat are different for each dolphin species, but usually, they avoid extreme cold waters, so they are not found in the polar zones.

Dolphins are found living in bodies of water around the world. They inhabit all of the oceans and some important rivers. Most of them live in saltwater, but a few species thrive in freshwater.

The habitat of dolphins varies according to environmental factors and food accessibility. They are smart creatures with the intelligence to modify their habitat when needed for survival.

PARTICULAR DISTRIBUTIONS

For example, the Bottlenose Dolphin dwells in all of the oceans, and they tend to live close to the coastline. Migration is a big part of life for some dolphins. They have to move where there is enough food; This is why some locations where there used to be dolphins either have very few or none anymore. Even changes in water temperatures can be reasons for them no longer to return to locations they once called home. Some successfully migrate hundreds of miles annually.

Open water species tolerate colder temperatures than coastal dolphins.

The Atlantic, Pacific and Indian Oceans and their seas host a large number of dolphin species since they prefer tropical, subtropical and warm waters. However, talking about the particular distribution of dolphins means addressing the place where each species live as they differ from each other.

Also, some species are distributed over large areas while others may inhabit a small region. Other species are particularly endemic to a zone, and some may have different populations scattered over an extensive range. Each species is a different case.

Two common dolphins jumping in the Sea of Cortes, Mexico.

The Pacific Ocean is habitat to several species, such as the bottlenose dolphin (Tursiops truncatus), perhaps the best-known dolphin, with a vast territory ranging from Japan to Australia and from the southern United States to Chile and Hawaii. In the Atlantic, the bottlenose dolphin dwells from North America to southern Argentina in the western part of this ocean and from Norway all the way down to the coasts of South Africa in the east. This species is also common in the Mediterranean Sea and the Indian Ocean.

Some dolphins out there live in much smaller habitats. For example, the Yangtze River Dolphin only dwells in the river of the same name. Hector’s Dolphins inhabit the coastal areas of New Zealand. They tend to be scattered there around the South Island.

The Short-beaked Common Dolphin (Delphinus Delphis) mainly inhabits the Mediterranean Sea and the northern part of the Atlantic Ocean. The Chinese white dolphin (Sousa chinensis) only dwells in the waters of the Indian and Pacific oceans.

Additionally, five river species exist that only inhabit the freshwaters of the Amazon, Ganges, Yangtze, Rio de la Plata and Indus rivers respectively.

GENERAL AND SPECIFIC HABITATS

The habitats of dolphins are also very diverse. They can be found in ports, bays, gulfs and estuaries and frequently in the shallow waters of the continental shelves. Previously it was believed that dolphins could not dive more than 200 meters deep, but apparently, some species have the feasibility of diving about 300 meters deep, a conclusion reached by finding remains of benthic fish in the stomachs of some specimens.

Some individuals prefer living in the open ocean while others fancy the conditions near the coasts. The Hector’s dolphin (Cephalorhynchus hectori), for example, can live only in shallow waters near the coastline. In contrast, the Spinner dolphin (Stenella longirostris) lives in the pelagic zone of high seas.

Open ocean dolphins seem to tolerate cold temperatures better than the coastal species. They rarely get close to the coasts. In contrast, coastal dolphins prefer warm and tropical waters, and their small body allows them to enter narrow and shallow places such as estuaries and river channels.

One thing is for sure: Dolphins visit areas with abundant prey within their habitats. Whether or not it is shallow water, most of these cetaceans prefer the pelagic area of ​​the sea where is easier finding and catching food. If the food supply decreases, dolphins tend to migrate to areas where there is no shortage, so their eating habits also change.

Since most species do not tolerate frozen waters they can migrate in search of warmer places during the seasons when temperatures drop, and vice versa. Dolphins also consider the migration patterns of their usual prey and their breeding habits to move from one site to another and perform seasonal migrations.

River Dolphins, for their part, inhabit the river basins of their distribution areas, along with the banks of the main channels and smaller channels. Some river dolphins venture to explore the forests when the rainy season floods them.

If you want to know the distribution and habitat of a particular species, do not hesitate to visit the Species section.

References

bioexpedition.com/dolphin-habitat-and-distribution/

https://seaworld.org/en/animal-info/animal-infobooks/bottlenose-dolphins/habitat-and-distribution/

http://www.scielo.cl/pdf/revbiolmar/v36n1/art11.pdf

http://www.iucnredlist.org/search

Sam H. Ridgway, Richard John Harrison. Handbook of Marine Mammals: The Second Book of Dolphins and the Porpoises, Volumen 6. 1998.

Sousa teuszii

INFORMATION AND CHARACTERISTICS.

The Atlantic humpback dolphin is a toothed cetacean native to, of course, waters of the Atlantic Ocean but whose populations are at least 2,000 kilometers apart from each other. This species is a close relative of the Chinese white dolphin (Sousa chinensis).

HOW DO THEY LOOK? PHYSICAL CHARACTERISTICS.

Morphology.
Sousa Teuszii is a robust dolphin, with a narrow and mid-sized snout and rounded head because of his big melon. It has a very pronounced hump on which it raises a broad and rounded dorsal fin. It has a wide caudal fin with a notch in the center.

Order: Cetacea
Family: Delphinidae
Genus: Sousa

Weight and size.
Males of the Atlantic Humpback Dolphin are larger than females, and the length of an adult is 1.8-2.6 meters. The weight is around 100-139 kilograms.

Skin Coloration.
The back and sides of the animal have a slate gray color while the belly is light gray.

Distinctive characteristics.
Undoubtedly, its most striking feature is the hump on the back on which the dorsal fin is.

WHERE DO THEY LIVE? DISTRIBUTION AND HABITAT.

The Atlantic hunchback dolphin inhabits warm, tropical waters of the eastern part of this ocean, in the west coast of the African continent from Morocco to Angola.

It dwells in coastal and shallow waters about 2 kilometers from the coast, in bays, deltas, estuaries with mangroves, canals, and rivers within its range of distribution although it does not go upriver far from the ocean. It is not a river dolphin.

Despite its preference for shallow waters, it is possible that this dolphin stays around reefs to take shelter from predators and to swim along the seabed.

WHAT DO THEY EAT? DIET AND EATING HABITS.

This cetacean feed on fish, crustaceans, and cephalopods. Among their favorite prey are mullets, breams, herrings, sardines and squids.

Their feeding habits vary according to their habitat but usually coordinate with a pod to capture their prey. In Mauritania, it associates with local fishers to catch mullets, in Senegal it enters the brackish water channels when the tide rises and returns to the ocean when the tide get low. In any case, its echolocation plays a crucial role in the detection of their food.

HOW DO THEY BEHAVE? BEHAVIOR.

The behavior of this dolphin does not seem to have much in common with that of other curious and energetic dolphins. On the contrary, it is a slow-moving species that swim at about 5 miles per hour. During the day, it swims alone or in groups of 5 to 7 individuals, but the maximum number of members in a pod is around 25.

It is quite shy and does not intend to establish contact with humans, and it even avoids boats. It reaches the surface to breathe every minute but can be under the water for up to 3 consecutive minutes. It can perform acrobatic jumps, but it is not very common to see it doing it. It communicates by whistles and a kind of squealing.

HOW DO THEY REPRODUCE? MATING AND REPRODUCTION.

The Atlantic humpback dolphin is a polygamous animal that mates with multiple partners throughout its life. Most of the information on the reproductive habits of this dolphin are hypotheses created from their closest relatives, the other members of the genus Sousa.

It is unknown at what age they reach sexual maturity, but many individuals begin to reproduce between four and eight years of age. A specific mating season is unknown, although, due to the number of births between March and April and an apparent gestation period of 12 months, males and females breed during the summer months, as the Chinese white dolphin (Sousa Chinensis chinensis).

A female usually has one offspring which at birth, it has a length of approximately 1 meter and weighs between 9 and 11 kilograms. 24 to 48 months later the mother weans her calf, but they can stay together for more time. After 4 or 5 years, the calf separates from its mother and joins another pod of dolphins.

WHAT IS THEIR CONSERVATION STATUS? THREATS AND CONSERVATION.

The Atlantic humpback dolphin has a conservation status of “Vulnerable” in the Red List of the International Union for the Conservation of Nature (IUCN) as its coastal habitat, very close to human populations, makes this species prone to be affected by the Anthropogenic activities.

Conservation status: “Vulnerable.”

In its natural habitat, this dolphin only has to be aware of the orcas that can feed on them, but this cetacean usually shelters in coral reefs avoiding them. On the other hand, its greatest threats are those related to man, and are the following:

– Hunting.
In some parts of West Africa, native communities catch this dolphin for human consumption.

– Bycatch.
In the coastal waters of Senegal, Gambia and other African countries, populations of this species are already scarce, because for many years the entanglement in fishing nets has caused bycatch which still happens today.

– Reduced food availability.
Overfishing affects the availability and abundance of their usual prey, which can fragment the food chain.

– Destruction and degradation of their habitat.
The destruction of mangroves and the contamination of coastal waters directly affect the survival of this dolphin.

– Boat collisions.
As they dwell close to the coast and the marine traffic in their distribution range is high, they are continuously hit by boats and propellers causing life-threatening injuries.

CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) included the Atlantic humpback dolphin in Appendix I of the most endangered species, and therefore the organization prohibits commercial hunting of this dolphin.

References

Distribution, status, and biology of the Atlantic humpback dolphin, Sousa teuszii (Kükenthal, 1892)

http://www.iucnredlist.org/details/20425/0

http://animaldiversity.org/accounts/Sousa_teuszii/

http://www.fao.org/fishery/species/18237/en

(Stenella frontalis)

The Atlantic spotted dolphin is very long, with a size of about 7 ½ feet when fully mature. They can weigh from 240 to 360 with the males being much larger than the females. They develop unique spots all over their bodies as they get older. Young ones don’t have any spots and those that are mature may only have a handful. It is for this reason that the Atlantic spotted dolphin is often misidentified.

The top of their bodies are a dark gray or a dark black. Underneath it is a white or cream color. On the dark part of their bodies they will have white spots and on the whitish areas they will develop dark colored spots.

Distribution

The Atlantic spotted dolphin is only found in the ocean. They are known to live in a variety of locations including the oceans around the United States, Africa, Europe, the Bahamas, and the Gulf of Mexico. They have significantly increased in numbers in the Bahamas. There are now hundreds of them when only a couple of decades there were less than 100 there. It is estimated that there are more than 100,000 Atlantic spotted dolphins out there.

Some of them that live along the Gulf of Mexico do migrate annually. Others tend to move long distances each day but not out of a need to follow a migration pattern.

Behavior

They are excellent when it comes to communication. They use a variety of loud clicks and whistles to talk with each other. They form groups of about 50 and they are also known to move around with other species of dolphins without any conflicts among them. There is a hierarchy among these dolphins that depends upon many factors including their size, age, and gender.

They are extremely protective of their young and will help each other to care for them. They also tend to do their best to protect the pregnant females from enemies including sharks.

Diet and Feeding

Their main food sources include octopus and various types of small fish. Most of the time they will fish at night. They also tend to hunt in groups as they have a tactic that allows them to get their prey into a big circle. Then they are able to come at these schools of fish from all angles.

Reproduction

There isn’t too much known about the reproductive habits of these dolphins. It is estimated that it takes 11 months from mating to birth. They are born without any spots but about one year of age they begin to develop. It is along this same period of time that the mothers will stop offering milk to them.

Conservation

One of the biggest threats to the Atlantic spotted dolphin is the amount of pollution that is found in their natural environment. Many types of efforts have been initiated to help clean up these bodies of water. At the same time educating the public about not polluting has also helped to reduce it. Still, there is plenty more than has to be done in order to resolve the problem.

Human interaction

This particular species of dolphin is very timid. They have been known to come right up to humans that are visiting the areas of the Bahamas. This has become one of the main tourist attractions in that area.

Many of them are killed annually due to illegal hunting by fisherman. They want to reduce the number of them so they can produce more product in their fishing nets. Others are accidentally captured in those nets so they may drown or become severely injured.

References

William F. Perrin, Bernd Würsig, J.G.M. ‘Hans’ Thewissen. Encyclopedia of Marine Mammals. Academic Press, 2009. Page 54.

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

http://www.iucnredlist.org/details/20732/0

http://www.cms.int/reports/small_cetaceans/data/S_frontalis/s_frontalis.htm

Striped Dolphin Jumping

Image Courtesy of: U.S. National Oceanic and Atmospheric Administration

//www.youtube.com/watch?v=iEvV2iycNgw