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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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A sea monster attacks a ship in an illustration for 20,000 Leagues Under the Sea by Jules Verne. The illustration is by publisher and artist Pierre-Jules Hetzel, who is most famous for his drawings in Verne's books. This...
Many sperm whales stranded on beaches or caught by whalers exhibit telltale...
Two bright orange anemonefish ( Amphiprion ocellaris ) poke their heads...

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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...
What is this bizarre, spiky-looking organism? Hint: it can be found in tropical areas of the Pacific and Indian ocean basins crawling slowly over coral reefs and devouring any living coral polyps...
Ghost crabs are often seen scuttling quickly along beaches at night, when they emerge from their burrows to feed, and can be difficult to photograph in the wild. They are common in Moorea, an island...
This venomous box jelly ( Chiropsalmus quadrumanus ) was collected off the coast of South Carolina. The specimen now resides in the Smithsonian’s marine collection . It's venomous sting can be lethal...
In this close-up photo, you can actually see the photosynthetic algae, or zooxanthellae, living inside a tiny coral polyp. Look for the brownish-green specks in the colorless polyp. Corals depend on...
The sargassum is coated with encrusting organisms, such as bryozoans and hydroids, that use it as a perch to filter feed in the oceanic waters, as well as crustaceans such as thos swimming crab...
The festive Christmas tree worm ( Spirobranchus giganteus ) lives on tropical coral reefs and resembles a fluffy fir tree adorned with ornaments. The multi-functional branch-like appendages are used...
In recent years, blooms of jellyfish, such as these moon jellies ( Aurita aurita ) in the Chesapeake Bay, have become more common around the world for a number of different reasons . One result of...
Most wild seahorses (here the thorny seahorse Hippocampus histrix ) are monogamous and some species mate for life. Searching for mates can be difficult and risky since seahorses are poor swimmers,...
The over 1,000 species of ribbon worms ( Nemertea ) are mostly found in marine environments (like the Hubrechtia found in a mud flat, in the photo). These worms have both a mouth and an anus (unlike...
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! They play an...
The Arctic comb jelly or sea nut ( Mertensia ovum ) is commonly found in the surface (top 50 meters) in cold, northern waters. Like other cydippid ctenophores, it has two tentacles fringed with...
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...
Researchers in Moorea use a variety of tools to collect organisms. Some are simple, everyday items like buckets and brushes, and some are…a little stranger. Here, two researchers use a “yabbie pump”...
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...
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...
This new species of lobster is blind—an adaptation to deep-sea life —and has very bizarre claws, or chelipeds. It was discovered about 300 meters (984 feet) deep in the Philippine Sea by a Census of...
Smithsonian Zoologist Dr. Clyde Roper (rear) and museum specialist Mike Sweeney examine the mantle of a dead giant squid. Everything we know about giant squid comes from studying specimens found...
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...
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