Did you know dolphins are really whales? And that all dolphins are in the same family?
Dolphins are easily recognized, and well-loved marine animals. Here you can learn some fascinating facts about dolphins.
Stuart Westmorland/Photographer's Choice RF/Getty Images
Dolphins are toothed whales - also called odontocetes. So...they have teeth, but what are their other characteristics? Dolphins have: streamlined bodies, a rostrum with a pronounced "beak", cone-shaped teeth, and one blowhole.
If you look just at taxonomy (the classification of organisms), it's pretty easy to tell which cetaceans are dolphins and which aren't - all dolphins are in the Family Delphinidae
. Animals in this family have streamlined bodies and cone-shaped teeth, an important distinction that sets them apart from porpoises
, who have flat or spade-shaped teeth.
Did you know that orcas (killer whales) are also dolphins? They are in the family Delphinidae, and are the largest dolphin. Male orcas can grow to 32 feet in length while females can grow to 27 feet. Orcas can weigh up to 11 tons (22,000 pounds).
The first dolphinarium in the U.S. opened in 1938.
Bottlenose dolphins are one of the most easily-recognized dolphin species. In the wild, they swim close to shore in some places, like off the southeastern U.S. But they have also been displayed in captivity for a long time. Cetaceans were held in captivity starting in the late 1800's, but the first oceanarium as we know it in the U.S. started when Marine Studios, now Marineland of Florida, opened in 1938 and exhibited bottlenose dolphins. According to their web site, "The original vision for Marineland was an effort to duplicate the variety of marine life as it exists in nature for the purpose of filming scenes for motion pictures and newsreels." In 1947, the first successful dolphin birth in human care occurred at the facility.
Annually, millions visit marine parks like Marineland and SeaWorld to see orcas and other marine animals, although there is a growing movement against having marine mammals in captivity.
Dolphins eat fish, squid, pinnipeds and even other whales.
Spinner dolphins, which are found in tropical and subtropical waters in the Pacific, Atlantic and Indian Oceans, are very active animals, which gather in large pods and are known for their leaping, spinning behavior, which is so dramatic that it can be seen from a distance. Their amazing spins can involve more than four revolutions of their body. These dolphins can grow to about 7 feet in length and 170 pounds in weight, have distinctive, slender beaks and may have an unusual, backwards-facing dorsal fin
© Jennifer Kennedy, Blue Ocean Society for Marine Conservation
While some use the terms 'dolphin' and 'porpoise' interchangeably, these are two words used to describe two distinct groups of animals. Dolphins, as mentioned above, are in the family Delphinidae, which contains 36 species. Porpoises are in the Family Phocoenidae
, which contains 7 species. Overall, dolphins generally are larger, have a more pronounced "beak," and have cone-shaped teeth. Porpoises are usually smaller than dolphins, have a more blunt snout, and have flat or spade-shaped teeth.
A dolphin's body temperature is about 98 degrees.
Like humans, dolphins are mammals, which also means that they are endothermic and must generate heat to maintain their internal body temperature. Despite sometimes living in chilly water, the body temperature of dolphins is around 98 degrees, just like ours. Dolphins keep warm using their blubber. This blubber layer is thicker in dolphins that live in cold water.
Dolphins also minimize heat loss and regulate their body temperature using a countercurrent heat exchange system. Areas away from the animal's core, such as the tongue, flippers, tail and dorsal fin, don't have insulating blubber. But they do have a system in which warm blood in the animal's arteries travel next to cool blood in the veins. The heat in the arterial blood is transferred to the blood in the veins, so that it warms up as it gets closer to the dolphin's core, and also minimizes heat loss.
When a cetacean takes a deep dive, blood is shunted to the body core to conserve heat and bring oxygen to areas it is most needed. If a dolphin needs to cool off, it increases circulation to its extremities, including the flippers, flukes (tail) and dorsal fin, which will allow heat to be lost to the surrounding environment.
In this case, it's not a fruit, but an organ. Like other odontocetes, dolphins have an organ in their head called the melon. This organ focuses clicking sounds that the dolphin makes when it is using echolocation
, in which the dolphin produces high-frequency sounds that bounce off of objects or prey in front of them. This allows them to determine the size, shape, density, distance and even the texture of the object in front of them. Echolocation can be used in finding prey, but is also thought to be used for navigation, communication, and keeping groups of dolphins together.
© Jennifer Kennedy, Licensed to About.com
While we don't know everything about how dolphins sleep, we know that their whole brain doesn't go into a deep sleep like ours does. Dolphins rest one half of their brain at a time, which allows them to go to the ocean surface when they need to breathe, monitor their environment for predators or other dangers, and keep an eye on their pod-mates. A dolphin in one study
was even able to successfully locate targets using echolocation for 15 days straight.