DOLPHINS ARE CETACEANS

All dolphins belong to the cetacean infraorder which also includes whales, dolphins, and porpoises.

The Cetacea infraorder is broken down into two parvorders. The first is the Mysticeti, which is made up of Baleen Whales, a group that captures prey by straining water through a series of baleen plates in their mouths which act as filters to collect the food.

ODONTOCETI PARVORDER, THE TOOTHED CETACEANS.

The second parvorder in the Cetacea infraorder is the Odontoceti; a group made up of toothed whales which have several families and superfamilies.

The first family is the Ziphiidae, which is composed entirely of big toothed whales like the beaked whales, a group of deep divers, rarely seen by humans.

The second family in the Odontoceti parvorder is the Physeteridae, which includes only the Sperm Whale,

The third is the Kogiidae which includes the Pygmy Sperm Whale, and Dwarf Sperm Whale.

The fourth family is the Monodontidae family, which includes the Beluga Whale and the Narwhal.

The Superfamily Inioidea includes the four families of river dolphins, and all the species that dwell in freshwater belong to this group.

The Stenidae family, includes the Rough-Toothed Dolphin, Pantropical Spotted Dolphin, Striped Dolphin, Spinner Dolphin, Short, Tucuxi, Guiana Dolphin, Chinese White Dolphin.

The Delphinidae family is made up of oceanic dolphins including:

The last family in the parvorder is the Phocoenidae family, which includes several species of porpoises like the Harbor Porpoise, Spectacled Porpoise, Black Porpoise, Black Finless Porpoise, Dall’s Porpoise, True’s Porpoise, Finless Porpoise, and Cochito Porpoise.

The name Dolphin comes from the word womb, and it is believed to be the Greek saying for fish with a womb.

DOLPHIN OR WHALE?

The largest dolphin species is the Orca, which is commonly known as the Killer Whale. These dolphins can be over 31 feet long when fully grown, a size which has provided them with the colloquial name of whales although they are dolphins.

There are all types of dolphins, some live in shallow waters near the coasts, but other prefer the high seas. Some fancy warm tropical waters while some species inhabit circumpolar regions. There are great differences among the species of dolphins, and that is why there are various genus and families.

In 2011, scientists discovered a new dolphin species in Big City Harbor around Australia. The novel dolphin got the colloquial name of Burrunan Dolphin and is believed to inhabit only two areas at this time. There are about 100 of them in Port Phillip Bay around Melbourne and about 50 more of them in the coastal lakes of Gippsland which is about 100 miles away.

The type of dolphin you will see in a given area depends on environmental factors such as food availability and the temperature. The time of year also is a factor due to the migrational patterns of most dolphins. Studies also indicate that there are differences among the species of dolphins regarding their skull size and form, variations that may lead to future taxonomical changes.

Young dolphins are called calves, and the female adults are cows. The male adults are bulls, and a group of them is called a pod.

Perhaps the most popular of all dolphins is the Bottlenose Dolphin; This is the species you often see in books, movies, and when you visit an aquarium. They are intelligent, easy to train, and they are more likely to approach humans in the wild than other species.

River Dolphins live in freshwater, and they inhabit some of these systems in South America and Asia. They are smaller than most oceanic dolphins, with an average size of about 8 feet when fully mature. They can be various colors including brown, gray, or pink.

The Roughed Tooth Dolphin, as some other species, is harder to spot out there in the ocean because they prefer waters with great depths. They can weigh around 350 pounds and measure about 8 ½ feet long. They have a small head and feature a long snout, lacking the crease on the melon that other dolphins have separating the beak from this organ.

The square-shaped head of the Risso Dolphin is a telling sign of what species you are seeing. They don’t have any teeth in the upper jaw, but they have several pegs-like teeth on the bottom jaw.

The Striped Dolphin gets its name from the blue and white stripes on its body. This species is believed to have the highest population in the world as well as the biggest overall distribution of that population. If you want to be impressed by acrobatics, check out this Dolphin.

The Common Dolphin was very respected in the early cultures. Researchers have found items from the Ancient Greek and Roman times picturing this cetacean.

The Dusky Dolphins tend to live in waters cooler than the temperatures preferred by other species of dolphins. They can be found in coastal regions as well performing astonishing leaps out of the water.

The Killer Whale is the most remarkable dolphin due to its size and strength. They can take down seals effortlessly which is important due to the significant volume of food that they need to consume on a daily basis.

The Pilot Whale can weigh up to 5,000 pounds and be up to 24 feet long being the second largest dolphin only after the Killer whale. They are believed to be the most social of the dolphin species.

References

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

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

Mark Simmonds. Whales and Dolphins of the World. New Holland Publishers, 2007.

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Introduction

There are only five species of dolphins that are able to thrive in freshwater and the Amazon River Dolphin is one of them. Many people assume that all dolphins live in saltwater so this is interesting to learn if you weren’t aware of it. There are several subspecies of River Dolphins to learn about.

Description

Depending on the location where they reside, River Dolphins will vary in size. Some of them can be up to 8 feet long but most of them are much smaller than that. They can also be found in a variety of colors. Some that you are known to exist include gray, black, brown, pink, yellow, and white. Due to the many different colors, they are often mistaken for other forms of aquatic life.

Distribution

The River Dolphin, as the name implies, lives in Rivers and that means they are able to survive in freshwater. They tend to stick to the brackish and coastal regions. They are found in the

Amazon, Ganges, Yangtze, Mekong, and Indus Rivers. Many of these rivers are home to very poor villagers and the locations can be very dense.

Plenty of these rivers are filled with dark, murky water and plenty of pollution. What is very interesting is that they can live in conditions that other species of dolphins would not be able to. It isn’t understood why this is possible, and more research has to be done. With so few species being able to live in freshwater, there are some theories but no definite answers at this time.

Behavior

River Dolphins are very social, and like others, they form pods. There can be just a few of them or more than 100 in a pod. They do form very strong bonds and they are quite protective of each other. The young tend to be secured in the middle of the pod in order to keep them safe. The females have also been noted to care for the young of each other in a cooperative effort.

These dolphins are believed to be very social and to have a complex hierarchy that can be hard to fully understand. They tend to have some pods that have primarily females or males in them. This could be part of their social organization.

Feeding

Fish are the main components of the diet for the River Dolphin, and they can eat large amounts of them daily. They use a variety of differenttechniques to get the schools of fish with ease. Usually, these efforts involve teamwork and collaboration that is very in sync and interesting to observe. For larger pods, they often break up into smaller groups for feeding purposes to be carried out.

Reproduction

The time of year for mating can vary based on the location of the River Dolphin. The females usually are ready to mate around 8 years of age and for the males it is about 10 years old. The males may heavily compete with each other for mating. The young will be born from 10 to 12 months later, tail first.

The pod is very protective and they will help the mother during the birthing process. They will protect the young calf and help it to the surface for air. They will also help keep predators away. The young will grow rapidly due to the fat content found in the milk that the mother produces. They will drink the milk for 1 ½ to 2 years, but they will also start to consume fish when they are about 6 months old.

Conservation Status and Threats

The River Dolphin is considered to be in a range from vulnerable to critically endangered. It is hard to get a good idea of the number of them due to the different species and their habitat. There are plenty of issues for the River Dolphin to worry about in their natural habitat. They may be caught up in fishing nets or collide with boats. Heavily pollution has played a vital role in the reduction of numbers of them in many locations.

Some of the conservation efforts involve fishing with better equipment and tools. However, since the rivers where plenty of the dolphins live are around very poor cultures that can be tough to improve. Overfishing is also a concern as the villagers heavily depend on the food for survival. Yet that can leave a lack of food for the dolphins to survive. Pollution problems are also higher in areas where they don’t have proper water and sewer systems in place.

One of the River Dolphins called the Baiji, has declared functionally extinct in December of 2006. The last time one of them was seen in the wild was in 2004. While there were some reports in 2007 of sightings of one in the Yangtze River, it couldn’t be confirmed.