Invertebrates

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In a decade long project, which ended in October 2010, scientists with the Census of Marine Life traveled the world cataloging the ocean’s life forms. From Australia to China to the Gulf of Mexico...
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From the giant squid to microscopic squid babies, squids are beautiful and...
Since summer 2013, starfish along both coasts of the United States have been...
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Tiny plant-like organisms called zooxanthellae live in the tissues of many...

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Like its terrestrial namesake, the Venus fly-trap anemone ( Actinoscyphia sp.) sits quietly and waits for food to drift into its outstretched tentacles, which are lined with stinging harpoons called nematocysts. Of course, this...
Census of Marine Life researchers discovered this unusual transparent sea...
Smaller than the head of a pin, this arrow squid (Doryteuthis plei ) embryo...

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Sample the surprising diversity of deep-sea corals. See some of the ways they differ in color, shape, and size. Explore more...
Dryodora glandiformis is a ctenophore found in Arctic and Northern European waters, bearing a pair of long and lovely tentacles.
A veined octopus ( Amphioctopus marginatus ) briefly leaves its hiding spot, a seafloor shell, to devour a crab.
This newly-discovered carnivorous sponge ( Chondrocladia lyra ) was found using robotic submersibles operated by the Monterey Bay Aquarium Research Institute 10,000 feet below the surface in dark...
Not all slugs (snails without shells) are slimy brown pests found in your backyard garden. In the ocean they come in a huge variety of colors — some match the background and are hard to spot, but...
Coral reefs are the most diverse of all marine ecosystems. They teem with life, with perhaps one quarter of all ocean species depending on reefs for food and shelter. This is a remarkable statistic...
From the giant squid to microscopic squid babies, squids are beautiful and fascinating. As cephalopods, the same family as octopuses and cuttlefish, they have no bones, and swim head-first through...
These watercolor sketches of Trapezia crabs were drawn by Frederick Bayer, a former Smithsonian coral biologist, in 1947. Trapezia crabs live on and within corals, feeding on their tissue and mucus,...
This hyperiid (in the genus Cystisoma) has only one pair of eyes—but they are very big. You can see them here as the entire surface of its head and the convex orange sheet of retinal cells in the...
A crown-of-thorns starfish ( Acanthaster planci ) on a reef in the Marianas Islands. An “outbreak” of these coral-eating starfish can decimate a reef, and they have done great damage on Australia's...
Rudist clams are mollusks that went extinct about 65 million years ago. They were the reef builders of the Cretaceous Period, the heyday of the dinosaurs. Today corals have taken over the role...
by Fox Meyer Squids, octopuses, and cuttlefishes are among the few animals in the world that can change the color of their skin in the blink of an eye. These cephalopods —a group of mollusks with...
Alien-looking creatures like this deep-red jellyfish ( Crossota norvegica ) swim in the Arctic Sea. Learn more about Arctic sea life in our Under the Arctic Ice story, or at the home page for the...
A fringe of short tentacles surrounds the flattened bell of this tiny, transparent jellyfish ( Halicreas minimum ), which can be found at depths up to 984 feet (300 meters). But it would be hard to...
A small horseshoe crab ( Limulus polyphemus ) rests on seaweed in Stage Harbor, Massachusetts. Atlantic horseshoe crabs can be found along the coast of North America from the Yucatán Peninsula to...
Scientist Martha Nizinski holds a squat lobster ( Eumunida picta ) collected at the Lophelia reefs off Cape Lookout, North Carolina. Squat lobsters are extremely abundant there and are usually found...
Watch as barnacles feed on bioluminescent dinoflagellates. Barnacles are crustaceans (like crabs, shrimps and lobsters) that secrete their shells for protection while living attached to things like...
Seahorses make noise! Seahorses make noises that can be heard underwater similar to the sound of smacking your lips. They make them during feeding and courtship.
The feathery strands at the back of this nudibranch’s ( Chromodoris willani ) body are no mere adornment: they’re its gills! Nudibranchs, shell-less snails or sea slugs, are named for these tufted...
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