Cetaceans

Cetacean

• Order Cetacea includes whales, dolphins, and porpoises. • Cetacea comes from the Latin word cetus and means

“large sea animal”.• Cetology is the branch of marine science that studies

these animals.

Cetacean

• Cetaceans are mammals that are best adapted to aquatic life.

• Their body is fusiform(spindle-shaped). • Their forelimbs have been modified into flippers.• Their tiny hindlimbs are vestigial; which means they really

have no function. • They do not attach to the backbone and are hidden within

the body.

Cetacean

• Cetaceans are nearly hairless, and are insulated by a thick layer of blubber.

• As a group, they are noted for their high intelligence.

Cretacean

• There are about 90 species of Cretacean. • They are all marine except for 4 species of freshwater

dolphin. • The order is divided into 2 suborders, Mysticeti (baleen

whales) and Odontoceti (toothed whales, including dolphins and porpoises).

Cetacean

• As mammals, cetaceans need to breath air.• Because of this, they need to come to the surface of the

water to exhale carbon dioxide and inhale a fresh supply of oxygen.

• While they are diving, a muscular action closes the blowholes (nostrils), which will remain closed until the next time the animal comes to the surface.

• When it surfaces, the muscles open the blowhole and warm air is exhaled.

Cetacean

• Cetaceans’ blowholes have changed over time to a position on top of the head, allowing more time to expel stale air and inhale fresh air.

• When stale air, which is warm from the lungs, is exhaled, it condenses as it meets the cold air outside.

• As with any other mammal breathing on a cold day, a small cloud of steam appears.

• This is called the blow or the spout and is different in terms of shape, angle, and height., depending on the species.

• Cetaceans can be identified at a distance using this characteristic.

Cetacean

• Cetaceans can go underwater for longer periods of time than other mammals.

• Increased body size is one way of increasing the dive time of large cetaceans.

• An increase in body size means that there is an increase in muscle mass, therefore an increase in oxygen stored in those muscles.

• Another reason is that the metabolism of a larger animal is slower than a small animal; they will use less oxygen than smaller animals.

Cetacean

• Cetacean eyes are set well back and to either side of its head.

• This means that cetaceans with pointed beaks (such as dolphins) have good forward and backward vision, but others that have blunt heads (sperm whale), can see either side but not directly ahead or directly behind.

Cetacean

• Tear glands secrete greasy tears, which protect the eyes from the salt that is in the water.

• They also have a sphere-shaped lens in their eye. • This is very good at focusing high-end UV light, which is

most prominent in deep waters.• Cetaceans make up for their poor vision (except for the

dolphin) by having excellent hearing.

Cetacean

• Cetacean ears are also very small. • Life in the water has, over time, caused these animals not

to need external ears, whose function is to collect airborne sound waves and focus them in order to hear.

• Water, however, is a better conductor of sound than air, so external ears were no longer needed.

• Their inner ear, however, has become so well-developed that cetaceans can hear sounds from miles away and also the direction from which the sound comes.

Cetacean

• Some cetaceans are capable of echolocation. • Many toothed whales will click similar to echolocation, but

it has not been determined if they use echolocation. • Toothless cetaceans have little need for echolocation

because they prey on small fish that would be impractical to locate with echolocation.

• Some toothed cetaceans, such as dolphins and porpoises, do use echolocation.

• They emit a sound, which is called a click, which bounces off an object and then returns.

• With this ability, cetaceans can search for, chase, and catch fast-swimming prey in total darkness.

Cetacean

• Echolocation is so advanced in most toothed cetaceans that they can distinguish between prey and non-prey.

• Cetaceans also use sound to communicate, like groans, moans, whistles, clicks, or even singing, like the humpback whale.

Cetacean

• Cetaceans are separated into 2 groups in regard to food and feeding.

• Toothed whales usually have lots of teeth that they use for catching fish, squid, or other marine life.

• They do not chew their food, but swallow it whole. • In rare cases that they catch large prey, they will tear

chunks off and then swallow them whole.

Cetacean

• Non-toothed cetaceans have plates instead of teeth. • These plates are made of keratin and hang down from the

upper jaw. • These plates act like a giant filter, straining small animals

from the water.

Humpback Whale

• Megaptera novaeangliae

Orca

• Orcinus orca

Beluga Whale

• Delphinapterus leucas

Bottlenose Dolphin

• Tursiops truncatus

Blue Whale

• Balaenoptera musculus