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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...
The ocean is home to a phenomenal diversity of marine organisms. They have...
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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The blue crab ( Callinectes sapidus ) is one of the most important commercial species in the United States, especially in the Chesapeake Bay region on the Mid-Atlantic coast. Its populations are affected by local water quality,...
Like this ctenophore ( Aulococtena acuminata ), many animals that live in...
Sponges are animals that eat tiny food particles as they pump water through...

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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...

The Ocean Blog

This brightly colored squat lobster collected in Moorea is a common find among the coral heads. Although called lobsters, this group of crustaceans is more closely related to hermit crabs than to...
Like octopods and cuttlefishes, giant squid have eight arms. But they use their two much longer feeding tentacles to seize prey. The tentacles have powerful suckers at the ends. More about the giant...
A longshoreman stands in front of a large pile of oyster shells on waterfront pier in Atlantic City in 1910. Back then, oysters were incredibly abundant. In the late 1800s, fishermen pulled in 10...
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,...
Dr. Clyde Roper, Smithsonian zoologist and squid expert, tries to measure up to a giant squid specimen (Architeuthis) from New Zealand. The squid wins. More about the giant squid can be found in our...
A humboldt squid ( Dosidicus gigas )—also known as the jumbo squid—releases a cloud of ink at night in Mexico's Sea of Cortez. These large, carnivorous squids can reach more than 5 feet in length and...
The Baltic is a brackish sea, a unique combination of freshwater from rivers in the surrounding countries and salt water from the ocean. The low salinity levels are one of the factors that determine...
Over the last few days, a video of hermit crabs stampeding across the rocky shores of St. John in the U.S. Virgin Islands has taken the internet by storm. Where are the hermit crabs going, and why?...
Can you spot the amphipod ( Phronima atlantica ) in the below photo? She's the transparent lobster-looking animal in the middle, surrounded by her own eggs -- inside a sac that once was the "barrel"...
The shrimp shown in this picture is a lot smaller then it looks- most adult anemone shrimp will only grow to about ½-1 inches long. Anemone shrimp ( Periclimenes inornatus ), reside as the name...
A blue cod and sea pens , a unique type of cnidarian , speckle the seafloor in New Zealand's Fiordland region.You can see more beautiful underwater photos from Brian Skerry in his image gallery .
This male dancing fiddler crab ( Uca terpsichores ) has built a sand “hood” at the entrance to his burrow, which he hopes will attract females to his humble abode—as if that big beautiful claw of his...
The ocean is home to a phenomenal diversity of marine organisms. They have evolved to inhabit warm waters near the equator and the icy waters of the Earth’s poles. Marine life takes advantage of the...
How long have jellyfish lived in the ocean? This jellyfish fossil is from the Cambrian period, more than 500 million years ago. It was found buried in Utah —an area that used to be underwater,...
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