20 Mind-Blowing Fun Facts About Ocean Animals

Octopuses have three hearts and blue, copper-based blood.

One jellyfish, Turritopsis dohrnii, can revert to an earlier life stage, earning it the nickname 'immortal jellyfish.'

The mantis shrimp strikes so fast it briefly boils the surrounding water, creating a flash of light in a process called cavitation.

A blue whale is the largest animal ever to live, bigger than any dinosaur.

Sea otters hold hands (or wrap themselves in kelp) while sleeping so they don't drift apart.

Starfish have no brain and no blood, moving on hundreds of water-powered tube feet.

Some sharks must keep swimming to breathe, while others can pump water over their gills while resting.

Electric eels (actually a type of knifefish) can generate shocks of up to about 600-860 volts.

The clownfish and sea anemone live in a mutual partnership, the fish immune to the anemone's stings.

Seahorses are among the only animals in which males become pregnant and give birth.

A group of jellyfish is called a bloom or a smack.

The immense colossal squid has the largest eyes of any known animal, roughly the size of dinner plates.

Dolphins have signature whistles that function like names, and they call to each other by them.

Pistol shrimp snap a claw so fast it stuns prey with a shockwave, one of the loudest sounds in the sea.

Sea cucumbers can expel their internal organs to distract predators, then regrow them.

Some deep-sea anglerfish males fuse permanently onto females, becoming a living source of sperm.

Coral reefs cover under 1% of the ocean floor but support around a quarter of all marine species.

Parrotfish produce much of the white sand on tropical beaches by grinding up and excreting coral.

Green sea turtles can hold their breath for hours while resting and navigate thousands of miles back to their birth beaches.

Bioluminescent creatures light up much of the deep sea, using chemical reactions to glow for camouflage, luring prey, or communication.