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Unlike fish, whales and dolphins evolved from four-legged animals with limbs underneath their bodies, their backbones naturally bend up and down and not side to side. It is also why their tail fins are horizontal and not vertical like those of fish.

The tail fin, or fluke, is used for propulsion through the water. Although they no longer have hind limbs, whales and dolphins still have vestigial pelvis bones. In some species these are used to help support reproductive organs.

The tails of some whales, such as humpbacks, have distinctive markings which enables scientists to individually identify each whale.

Other uses for the tail include occasionally slapping them on the surface of the water as a form of communication or to stun prey at the surface or underwater. Another unusual activity employed by species such as southern right whales, is "tail sailing" where a whale will lift the tail vertically out of the water for long periods of time.

The pectoral fins (on each side) provide directional control and the dorsal fin (in those species that have one) provides stability whilst swimming.

Many individuals however have been documented without a “complete set” of fins (likely as a result of incidental entanglement in fishing gear, being hit by a boat’s propeller or a lucky escape from a predator) and therefore they can sometimes adapt quite well to losing part or all of a fin.

Amazing facts about whales and dolphins

Dive deeper into the world of whales and dolphins and learn more about their lives.

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Conran & Castillo 2_0715_Charlie Phillips
20140904 - Fife (A60) - Jared Towers
Breaching North Atlantic right whale

Facts about whales

Amazing facts about whales, the largest mammals to live on Earth.

Facts about dolphins

From the orca to the tiny vaquita, learn more about these creatures.

Record breakers

Whales and dolphins hold some incredible records.

Brain power

Just how intelligent are whales and dolphins?

Help protect whales and dolphins and their homes

By adopting a whale or dolphin, by making a donation, or by fundraising for WDC, you can help us save these amazing creatures.

Orca - Rob Lott

Adopt

Adopt an orca and help us protect these amazing creatures.

Bottlenose dolphins in the Moray Firth

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Your gifts help us take action to protect their homes.

Breaching North Atlantic right whale

Fundraise

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