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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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How many animals swim in the sea? It's not easy to count them all. To get a feel for the ocean's diversity, scientists, such as those involved in the Census of Marine Life , sail out on research cruises to collect and count as...
With a scientific name that means "the vampire squid from hell," you'd...
Zombie worms ( Osedax roseus ) eat away at the bones of a dead whale that...

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Nudibranchs are a kind of sea slug, and their 3000 species are found from the poles to the tropics in both shallow and deep...
The giant squid is among the largest invertebrates on Earth, but this deep sea creature has rarely been observed by humans -- alive. Over the centuries, many dead giant squid have washed up on the...
A thicket of white stony coral ( Lophelia pertusa ) shelters a squat lobster (Eumunida picta). This is the typical shape of this widespread species of deep-sea coral. See more pictures of coral in...
This orange boring sponge ( Cliona varians ) overgrows several coral species at Panama's Smithsonian Tropical Studies Institute. Boring sponges mechanically and chemically breakdown mollusk shells...
A morning sun star ( Solaster dawsoni ) loses its grip on a rock surface as its body slowly decomposes from starfish wasting syndrome off the coast of Vancouver in September 2013. These photos are...
When hoping to discover a pearl, looking inside one of the oysters you slurp may not be the best plan. Food oysters in the family Ostreidae are able to produce pearls, however these tend to be small...
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...
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...
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...
Polychaete worms are not your average cringe-inducing, writhing worms. (Okay, maybe some are.) They are fascinating, varied, and a critical part of our ocean. The visual variety among the more than...
Many sperm whales stranded on beaches or caught by whalers exhibit telltale circular scars like these. Only one thing could have made them: the strong suckers that line the giant squid’s eight arms...
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...
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...
Recently, Smithsonian National Museum of Natural History researcher Chris Mah and collaborators with the British Antarctic Survey and the Monterey Bay Aquarium Research Institute used molecular tools...
The loco ( Concholepas concholepas , often called the Chilean abalone, although it isn’t actually an abalone) is found along the entire coast of Chile.
The whitish spots on this fish are individual parasitic trematode worms. Trematodes have complicated life cycles that usually involve multiple hosts -- often starting in a snail and then moving on to...
This copepod Calanus hyperboreus (up to 7mm in length) lives in the Arctic , usually within 500 meters of the surface. To survive the cold Arctic winters, Calanus hyperboreus builds up dense fat (...
Flower-like clusters of polyps make up this coral colony. Their pink color comes from the zooxanthellae living inside. More about coral reef ecosystems can be found in our Coral Reefs featured story .
The Japanese spider crab is a large catch for any fisherman. With a leg span of 13 feet (4 meters) and an average weight of around 40 pounds (16-20 kg), it claims the title of largest crab. It may...
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