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.

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

]]> https://www.dolphins-world.com/frasers-dolphin/ Thu, 27 Apr 2017 05:27:31 +0000 http://www.dolphins-world.com/?p=84 Fraser’s Dolphin Facts

(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/secrets-of-dolphin-swimming/ Wed, 29 Jan 2014 05:30:30 +0000 http://www.dolphins-world.com/?p=586 Researchers of an aquatic park in California want to discover the reasons that make dolphins excellent swimmers. In this video, they carry out studies with a Bottlenose dolphin.

Did you know that dolphins swim up to five times faster than the best human Olympic swimmer? Many think that this is obvious, since they are aquatic animals; however, they are mammals like humans. This is the reason why they are doing experiments to measure their speed and energy usage. It should be noted that those studies do not threaten the lives of these beautiful aquatic mammals.

//www.youtube.com/watch?v=zp-Po76p5pw

When using echolocation, dolphins emit a series of sounds in the form of bursts that “bounce” or return as echoes which they detect, and allow them to measure the distance and the size of the object or animal. Undoubtedly, dolphins are one of the most intelligent species on our planet and above all, one of the most studied by researchers.

//www.youtube.com/watch?v=ZoNDW0zSRNo

The Chinese white dolphin inhabits the Indian and Pacific oceans from the southern coast of China in the east to eastern coast of Australia, including Indochina and part of the Indian Ocean.

The countries besides China, where it dwells are Taiwan, Hong Kong, Thailand, Vietnam, Malaysia, India, Pakistan, Australia, and Papua New Guinea.

• Dolphins are mammals; this means that they nurse their babies with milk from the mothers.

• Dolphins can swim up to 260 m. below the surface of the ocean.

• Dolphins can stay up to 15 minutes under water, but they cannot breath under the water.

• Dolphins use a technique called echolocation to find food and navigate.

• Dolphins live in groups formed by 10 to 12 individuals.

• There are 32 different kinds of ocean dolphins and 4 species of river dolphins.

• The largest dolphin is the “killer whale” (also known as Orca).

• The most known dolphin is the “ bottlenose dolphin”.

• Dolphins are warm-blooded.

• Dolphins communicate through sounds and whistles.

• Dolphins eat fish and squid.