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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 closures, or...
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The ocean is home to a phenomenal diversity of marine organisms. They have...
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This summer, many of you have likely enjoyed feasting on crabs, be they blue,...
Zombie worms don’t crave brains: instead they seek bones. The 1 to 3 inch (2 to...

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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–called zooxanthellae (zo-zan-...
In recent years, blooms of jellyfish, such as these moon jellies ( Aurita...
An orange brisingid starfish sits on a large reef of Lophelia pertusa, cold-...

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Coral reefs are the most diverse of all marine ecosystems. They teem with life, with perhaps one quarter of all ocean...
Several species of amphipod like this one, Gammarus wilkitzkii , live permanently within Arctic sea ice . These animals are endemic, meaning they only live here. They acclimate to a wide range of...
A rockfish finds refuge in a deep-sea coral—a red tree coral of the Primnoidae family in the Olympic Coast National Marine Sanctuary. Learn more about deep-sea coral reef ecosystems in our Deep-sea...
Some of the most otherworldly animals—like those straight from a science fiction story—can be seen in the open ocean at night. By drifting in the blackwater in a scuba suit just under the surface,...
A “pink meanie” jellyfish ( Drymonema larsoni )—a species found in the Gulf of Mexico and the Caribbean—feeds on a moon jelly ( Aurelia ). Dr. Keith Bayha from the Dauphin Island Sea Lab and Dr...
The Smithsonian's Department of Invertebrate Zoology has a collection of over 57,000 specimens from over 5,700 sites in the Gulf of Mexico, which are now catalogued on Google Earth . Below is a tiny...
This bright purple sea star is a new species found by the Census of Coral Reef Ecosystems , a project of the Census of Marine Life. This particular specimen was seen on the reefs of the French...
Sea cucumbers might have a cucumber shape, but are definitely animal, not vegetable… or fruit. They belong to the Phylum Echinodermata , which also includes sea urchins, sand dollars, sea stars and...
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...
Polarized sunglasses have become the norm for humans when they want to filter out the strong glare from the sunlight bouncing off of water in a horizontal direction. But how do animals do that live...
Scypholanceola aestiva looks like an armored alien of the deep. It doesn’t have compound eyes like other hyperiids, but instead sees variations in light using reflective cups embedded in the...
Shown here are several deep-sea coral species: From left to right is an unidentified purple octocoral, a small gold acanthorgorgiid octocoral, and a large colony of pink Corallium secundum . Basket...
These Pacific cephalopods illustrate the wide diversity among this group of mollusks. You can learn about a relative, the giant squid ( Architeuthis dux ), in our Giant Squid section.
This tiny, shrimplike creature is no more than 2.5 centimeters (1 inch) long, but it’s as ferocious as a shark. Its giant eyes spot prey. Huge claws grab the prey, and a tiny mouth rips it to shreds...
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.
Smithsonian Zoologist Dr. Clyde Roper , the world's foremost authority on giant squid, explores the squid collection at the National Museum of Natural History. He is passionate about giant squid and...
Most lobsters are a mottled brown color, but sometimes you can see a strange orange or blue lobster. And then, when lobsters are cooked, they turn bright red. Why is there such a rainbow of lobster...
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...
“It is strange to think of a sea turtle as an ecosystem,” says Amanda Feuerstein, program coordinator and research assistant at the Smithsonian’s National Museum of Natural History, “but they are…...
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