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humpback whale and calf underwater

Whales, Dolphins and Porpoises

Learn More About Cetaceans

Marine mammals in the cetacean family include whales, dolphins and porpoises. These animals are completely aquatic, meaning they spend all of their time in the ocean and cannot survive on land. 

Whales, dolphins and porpoises have two front flippers, and their tails are uniquely shaped into two horizontal extensions, called flukes, that provide tremendous swimming power.

Cetaceans are separated into two groups: toothed and baleen whales.

As their name suggests, toothed whales (or odontocetes) have teeth. They also have one opening at their blowhole. There are over 73 species of toothed whales, including sperm and beaked whales, belugas and narwhals, porpoises and dolphins, and even freshwater dolphins that live in rivers. They range in size from the 60-foot (21.1 m) sperm whale to the 5-foot (1.5 m) vaquita.

Toothed whales tend to be social and live in groups. Like bats, they use echolocation or sonar to detect objects in their environment. They produce sounds in the air passages in their heads, which are then projected out in front of them. The sound bounces off solid objects and returns to them (like an echo), so the animals are able to get a "picture" of what is around them.

humpback whale breaching with San Francisco in the background
photo © Allison Payne

Evolution and Adaptations

Millions of years ago, the ancestors of whales lived on land. Scientists believe these land ancestors looked like small dogs, but were probably more closely related to hippos and went into the ocean about 60 million years ago.

Over time, these ancestors adapted to survive solely in the ocean environment. Their front legs turned into paddle-shaped flippers, they lost their back legs, their tails grew larger and widened to form flukes, and they developed a thick layer of fat, called blubber, to keep warm in the ocean. Also, their skulls elongated and the nostrils shifted to the top of their heads (blowholes) to aid in breathing at the ocean's surface.

They developed a series of adaptations related to diving, which include the ability to store more oxygen in their blood and muscles and having more blood volume relative to their body size than land mammals.

Cetacean Conservation at The Marine Mammal Center

Population Status

Many whales are endangered, largely due to past hunting. Years ago, people used the oil from the blubber of whales for all sorts of items, including oil burned in lamps and ingredients for manufacturing lipstick. They also used whale meat to eat or make pet food, sinews for tennis racquet strings and baleen as supports in women’s underwear. A waxy substance called ambergris, which is from a sperm whale's digestive system, was used in making perfume. Ambergris was very valuable, and a large lump found by a beachgoer was worth a fortune.

Research Insight

Cetacean Research at The Marine Mammal Center

humpback whale tail visible above the water
photo © Bill Hunnewell

Name a Whale

Searching for a unique and memorable gift? Go whaley big for your loved one when you give the gift of naming a whale in their honor. Perfect for any occasion, this gift is one to be cherished because it helps protect whales and their ocean home.


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whales, dolphins, porpoises, marine mammal, toothed whales, baleen whales, endangered