What Are Three Characteristics that Dolphins & Whales Share?

Background

• One way to distinguish dolphins and whales is to examine their size. In general, whales are larger. Cetaceans can range in size from a tiny 39-inch-long dolphin to the blue whale, which is 82 feet long. Cetaceans are divided into two main categories: toothed whales and baleen whales. Toothed whales have one blowhole and possess teeth. Ocean and river dolphins, sperm whales, orcas and belugas fall into the toothed whale category. Baleen whales have two blowholes and furry plates instead of teeth. Examples of baleen whales include the humpback whale and the blue whale.

Blowholes

• Dolphins and whales both have blowholes. A blowhole is an opening on the top of the mammal's head. Fish have gills, which help them draw oxygen from water into their bodies. Because dolphins and whales have lungs, not gills, they must rise to the surface at regular intervals to breathe out old water and draw fresh air into their lungs through their blowholes. According to "The Oceans" by Ellen J. Prager and Sylvia A. Earle, in the evolution of cetaceans, external nostrils moved from the front of the head to the top and back of the animal's skull to form a blowhole.

Breaching

• Both whales and dolphins demonstrate breaching behavior. Breaching refers to the act of leaping out of the water and then landing back on the ocean's surface with a splash. Dolphins can propel themselves high up out of the water and perform twists, somersaults or turns. Humpback whales are known for their breaching, and dusky dolphins are known for their high leaps and acrobatics. Large whales may raise themselves part way out of the water and belly flop. Whales and dolphins can roll over near the water's surface and slap their tails on the water to create a splash.

Echolocation

• Echolocation is the ability to measure the location of an object, such as prey, by how long it takes for an echo to return from it. Dolphins and whales have the ability to echolocate and emit high-frequency sound waves. The sounds, which sound like rapid clicks, likely originate in the animals' nasal passage tissues. The animals use their ears to pick up the echos of their sounds after the sounds reflect off objects. Dolphins and toothed whales also appear to use sound for communication and social interaction.