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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...
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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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Marine parasites may be small in size, but they can be present in very high...

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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 these blooms is that there is...
An orange brisingid starfish sits on a large reef of Lophelia pertusa, cold-...
These watercolor sketches of Trapezia crabs were drawn by Frederick Bayer, a...

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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...
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...
Humans have long been captivated by what we now call the giant squid ( Architeuthis ). This image gallery gives a glimpe into our fascination with the animal. For a long time, people saw mysterious...
“This image was captured during an evening dive in water where the largest migration on Earth occurs nightly," said Nature's Best Photographer Joshua Lambus. The migration he speaks of is the diel...
It is a well-known fact that for animals living in the deep sea, food can be scarce. The food that is around usually rains down from above as dead animals and organic particles from plankton living...
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...
This common octopus ( Octopus vulgaris ) doesn't have a jetpack to help him zoom through the water, but he's got something pretty close: a siphon that shoots water. (It's the little orange/yellow cup...
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...
A mangrove tree crab ( Aratus pisonii ) clings to a leaf near the Smithsonian Institution’s marine laboratory on Galeta Island, Panama, part of the Smithsonian Tropical Research Institute . During...
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...
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 close-up photo of a right whale's head shows dozens of hitchhikers—tiny crustaceans known as whale lice, or cyamid amphipods. They live on the rough patches of skin (known as callosities) on...
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...
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.
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...
Boring sponges get a bad rap. Their own name betrays them, announcing to the world that they are unexciting, ordinary and quite frankly, boring. However, if ever a misnomer existed, this is it. More...
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...
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...
Male fiddler crabs each have a single super-sized claw that they use as a weapon to threaten and fight other males and as beautiful adornment to attract females. Here, see a video of two male dancing...
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