What Are Whales?

by AMNH on

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What does the word "whale" bring to mind? For many, it might be the image of a blue whale, the largest animal that ever lived.

The blue whale model in the Milstein Hall of Ocean Life is 94 feet long.
© AMNH/D. Finnin

But did you know that dolphins and porpoises, which are far smaller and look quite different, are also types of specialized whales? Today, there about 80 species of living whales, or cetaceans.

These 80 species fall into two groups: baleen and toothed.

Humpback Whale
A type of baleen whale, humpback whales reach up to 50 feet long. 
Talia Romito and Sophie Webb/Courtesy of NOAA

Called mysticetes—a word derived from the Greek for “mustache” and “whales”—baleen whales are toothless. They feed by using their unique baleen—fringes of keratin hanging from the roof of their mouths—to help keep vast numbers of tiny prey (such as krill) in and filter water out. Blue whales, humpback whales, and gray whales are all mysticetes.

Bryde's Whale blowholes
Baleen whales, including the Bryde's whale pictured here, have two blowholes through which they breathe. Toothed whales have only one.
Isabel Beasley/Courtesy of NOAA


Called odontocetes—from the Greek for “toothed whales”—toothed whales are the bigger group, comprising about 70 of the whale species living today. The group includes beaked whales and sperm whales. (Sperm whales are far larger than most other species in this group—reaching about 60 feet long.)

Sperm Whale 2
Sperm whale
© Brandon Cole

The toothed-whale group also includes porpoises, dolphins (including orcas, also called killer whales), and the monodonts—narwhals and belugas.

Beluga whales are odontocetes, or toothed whales. Living mainly in Arctic waters, baby belugas are born gray; only later do they become white.
Laura Morse/Courtesy of NOAA

Toothed whales such as sperm whales hunt their prey one by one. They often use echolocation to find it and sometimes swallow it whole.

Killer Whale with Stellar Sea Lions
Killer whales are a type of dolphin, a group of specialized toothed whales.
Lance Barrett/Courtesy of NOAA


Learn more about the diversity of these marine mammals in Whales: Giants of the Deep, which opens at the Museum Saturday, March 23.