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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Hyperiid amphipods are small crustaceans related to sand fleas and distantly related to shrimp. They range in size from very tiny to more than 7 inches long, and are found at all depths of...
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Bioluminescence is one of the more captivating adaptations that have evolved in...
Octopuses are colorblind, but manage to blend into the background seamlessly—or...
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Fever. Aching muscles. Coughing. Sniffling. It’s flu season . Have you had your...

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Two bright orange anemonefish ( Amphiprion ocellaris ) poke their heads between anemone tentacles. Anemonefish are able to swim amongst the stinging tentacles without getting stung — but no one knows exactly sure how. One...
White abalones are slow-moving, algae-eating mollusks. Rapid overharvesting...
This forest of Christmas tree worms is a group of polychaete worms that live...

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Giant squid live up to their name: the largest giant squid ever recorded by scientists was almost 43 feet (13 meters) long,...
These corals from the Smithsonian collections are Stephanocyathus (A.) spiniger , a solitary, deep-water stony coral species. Around 74% of all deep-water corals are solitary, living as individual...
This halimeda crab’s disguise did not fool researchers in Moorea where it was collected. These crabs cover themselves with the green algae of halimeda for camouflage.
A giant squid engages in a struggle for survival with a sperm whale. Giant squid beaks and other undigested pieces of giant squid have been found in the stomachs of sperm whales . More about the...
Researchers use Autonomous Reef Monitoring Structures (ARMS) like this one to study the diversity of coral reef organisms. They leave the structures underwater for about a year. Then they retrieve...
Watch a Discovery video on Smithsonian squid expert Clyde Roper’s search for giant squid in Kaikoura Canyon off the coast of New Zealand. More about giant squid can be found in our Giant Squid...
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...
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...
Ocean creatures may not sing carols and go ice skating, but some celebrate the winter holidays all year round! So turn on the “Jingle Shell Rock” and celebrate with these intriguing ocean animals.
Squids come in a wide range of sizes but despite differences in size and shape, all work basically the same way inside. More about the giant squid can be found in the Giant Squid section .
Octopuses can change the texture and color of their skin to blend in with their surroundings. This day octopus ( Octopus cyanea ) has shaped itself like seagrass or some coral so hide from predators...
The yeti crab ( Kiwa hirsuta ), an unusual, hairy crab with no eyes, was discovered in 2005 on a hydrothermal vent near Easter Island. It represents not only a new species but also a new genus— Kiwa...
Using an ROV (Remotely-Operated Vehicle) equipped with a high-definition video camera, scientists can observe the life that flourishes beneath the Arctic ice . On this expedition, they discovered...
This hyperiid is one of twenty-four species in the genus Vibilia , distinguished by the paddle-like antennae on the front of its head. Vibilia are small (only 5-20 millimeters long) and their eyes...
Depending on whom you talk to, jellyfish are either fascinating, a nuisance, a toxic menace, or some combination of the above. Jellyfish plop into the media spotlight when their presence causes beach...
What are corals? Corals themselves are animals. But tropical reef-building corals have tiny plant-like organisms living in their tissue. The corals couldn’t survive without these microscopic algae–...
As it clings to a red sea fan, a feather star ( Cenometra bella ) gently waves its slender arms—filtering bits of food from the water. Also known as sea lilies, feather stars are related to sea stars...
This nudibranch has a few tricks up its sleeve: it steals jellyfish tentacles to use as weapons against its own enemies. How does it do this? Many fleshy, tentacle-like growths, called cerata (...
This beautiful spider conch ( Lambis chiragra ) was collected by Census of Marine Life scientists conducting research near China.
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