Invertebrates

Animals without backbones make up a huge percentage of the ocean’s biodiversity. They aren’t just small (like pteropods) or squishy (like jellyfish); the giant squid and corals that build huge reefs are also invertebrates.

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Marine parasites may be small in size, but they can be present in very high numbers and put together can weigh even more than all the top predators in an estuary or bay ecosystem!...
During the summer of 1998, scientists at the Virginia Institute of Marine...
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The blanket octopus can rip a poisonous tentacle from a Portuguese man-o-war...
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Hyperiid amphipods are small crustaceans related to sand fleas and distantly...

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Census of Marine Life researchers discovered this unusual transparent sea cucumber ( Enypniastes sp.) in the Gulf of Mexico at 2,750 meters depth. It creeps forward on its tentacles pretty slowly, at around 2 centimeters per...
Smaller than the head of a pin, this arrow squid (Doryteuthis plei ) embryo...
What are corals? Corals themselves are animals. But tropical reef-building...

DIVE DEEPER

Jellyfish and comb jellies are gelatinous animals that drift through the ocean's water column around the world. They are...
Giant squid have the largest eye in the animal kingdom. At up to 10 inches in diameter, people often describe it as the size of a dinner plate -- or, in other words, as big as a human head. Here,...
A mantis shrimp ( Odontodactylus scyllarus ) holds her clutch of eggs in her clubbed claws. Usually these claws are weapons that punch hard-shelled prey at speeds of more than 50 miles an hour...
Sponges are animals that eat tiny food particles as they pump water through their bodies. They are very common on Caribbean coral reefs, and come in all shapes, sizes and colors. There is great...
This much smaller hyperiid (in the genus Paraphromina ) has eyes that make up 45 percent of its body! Its many retinas, which researchers believe are used to maximize light detection, are the small...
Using a deep-diving ROV, the crew aboard Oceana’s research vessel Ranger were surprised to discover large colonies of deep-sea white coral in the Western Mediterranean Sea in July 2010. Most of the...
Brachiopods are an ancient group of organisms, at least 600 millions years old. They might just look like clams, but they are not even closely related. Instead of being horizontally symmetrical along...
Home is where the hull is: Since the dawn of seafaring, humankind has had to deal with pesky creatures, such as barnacles, that “foul” ship hulls and boat propellers like this one. Find out more in...
Recent scientific discoveries have revealed an underwater community of marine animals and other organisms that thrive in the dark depths of the ocean near hydrothermal vents and undersea volcanoes...
The Boreoatlantic armhook squid ( Gonatus fabricii ) is named for its fabulous (but dangerous) suckers. While most squids have just two rows of suckers lining each arm, armhook squids have four—and...
Found in Arctic waters, this rare deep-water species of larvacean , Oikopleura gorskyi , eats by filtering particles from the seawater it drifts through. Larvaceans build 'houses' around themselves...
Sperm whales have conical teeth on their long, narrow, lower jaw. The teeth fit neatly into sockets in the upper jaw, which has no teeth. This arrangement is a perfect adaptation for slurping up soft...
A veined octopus ( Amphioctopus marginatus ) briefly leaves its hiding spot, a seafloor shell, to devour a crab.
In this episode of the Podcast of Life , learn how three fiery, painful stings during an early morning swim in Hawaii changed the life of researcher Angel Yanagihara. Once the young biochemist had...
Fever. Aching muscles. Coughing. Sniffling. It’s flu season . Have you had your shot? If so, thank a horseshoe crab. In fact, if you’ve been put on an IV, had a medical device implanted, or received...
This image from a scanning electron micrograph magnifies the tiny teeth that cover the surface of the giant squid’s tongue-like organ, or radula . Seven rows of sharp teeth help direct tiny pieces of...
Methane gas, trapped deep within the Earth's crust, can slowly leak from cracks in the seafloor known as methane seeps. While we would never consider methane as food, in the deep sea where there is...
"While Komodo Island, Indonesia is famous for its giant prehistoric lizard, its underwater also holds unique marine species to treasure. The orangutan crab is one of them. With its maximum size of...
In 1874, Reverend Moses Harvey of Newfoundland bought a dead giant squid caught by fishermen. More about the giant squid can be found in our Giant Squid featured story .
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