Order Cetacea

Hawaiian spinner dolphins
Michael Nolan/Robert Harding World Imagery/Getty Images

The Order Cetacea is the group of marine mammals that includes the cetaceans - the whales, dolphins and porpoises.

Description

There are 86 species of cetaceans, and these are divided into two suborders - the mysticetes (baleen whales, 14 species) and odontocetes (toothed whales, 72 species).

Cetaceans range in size from just a few feet long to over 100 feet long. Unlike fish, which swim by moving their heads from side-to-side to swing their tail, cetaceans propel themselves by moving their tail in a smooth, up-and-down motion.

Some cetaceans, such as the Dall's porpoise and the orca (killer whale) can swim faster than 30 miles per hour.

Cetaceans Are Mammals

Cetaceans are mammals, which means they are endothermic (commonly called warm-blooded) and their internal body temperature is about the same as a human's. They give birth to live young and breathe air through lungs just like we do. They even have hair.

Classification

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Mammalia
  • Order: Cetacea

Feeding

Baleen and toothed whales have distinct feeding differences. Baleen whales use plates made of keratin to filter out large quantities of small fish, crustaceans or plankton from the sea water.

Toothed whales often gather in pods and work cooperatively to feed. They prey on animals such as fish, cephalopods, and skates.

Reproduction

Cetaceans reproduce sexually, and females usually have one calf at a time. The gestation period for many cetacean species is about 1 year.

Habitat and Distribution

Cetaceans are found worldwide, from tropical to arctic waters. Some species, like the bottlenose dolphin may be found in coastal areas (e.g., southeastern U.S.), while others, like the sperm whale, may range far offshore to waters thousands of feet deep.

Conservation

Many cetacean species were decimated by whaling.

Some, like the North Atlantic right whale, have been slow to recover. Many cetacean species are protected now - in the U.S., all marine mammals have protection under the Marine Mammal Protection Act.

Other threats to cetaceans include entanglement in fishing gear or marine debris, ship collisions, pollution, and coastal development.