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

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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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Sample the surprising diversity of deep-sea corals. See some of the ways they differ in color, shape, and size. Explore more...

The Ocean Blog

Found in the icy waters of the Arctic , Comb Jellies, or ctenophores like this one, of the Aulacoctena genus, are poorly known animals. With extremely fragile bodies, they are difficult to capture...
In 1874 Reverend Moses Harvey of Newfoundland displayed the giant squid he bought on the side of his barn, much to the dismay of Mrs. Harvey. More about the giant squid can be found in our Giant...
These deep-sea photographs show a variety of broad-collared enteropneusts or acorn worms . These wormlike animals make spiral tracks on the sea floor. All the species shown here are new to science,...
Like this ctenophore ( Aulococtena acuminata ), many animals that live in the midwater zone are red—making them almost invisible in the dim blue light that filters down from the sea surface. This...
There aren't any mummies or zombies buried under the seafloor: instead the ocean has its own terror from below, the bobbit worm ( Eunice aphroditois ). A couple inches wide and up to ten feet long,...
Climate and sea changes in the Southern Ocean create conditions that favor the growth of salps over krill , the latter of which are a vital food source for seals, whales, and penguins. Salps are...
Many jellyfish in the class Hydrozoa, such as this hydromedusa Aglantha digitale , are transparent and easily overlooked. Learn more about hydrozoan jellies and other jellyfish , and see more...
Acorn barnacles ( Balanus crenatus ) make a home on the carapace of an edible crab ( Cancer pagurus ). Much of the Baltic suffers from eutrophication that leads to oxygen depletion. The algae blooms...
A crown-of-thorns starfish ( Acanthaster planci ) on a reef in the Marianas Islands. An “outbreak” of these coral-eating starfish can decimate a reef, and they have done great damage on Australia's...
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...
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 ocean is home to many moms of all shapes and sizes: from charismatic polar bears and dolphins to small fishes and shrimps and more. Learn about some of the diverse parenting habits of marine moms...
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...
The yeti crab ( Kiwa hirsuta ), an unusual, hairy crab with no eyes, was discovered in 2005 on a hydrothermal vent near Easter Island. It represents not only a new species but also a new genus— Kiwa...
Comb jellies (such as this Bolinopsis species) are named for their combs: the rows of cilia lining their bodies that propel them through the ocean. Read more about jellyfish and comb jellies .
A diversity of deep-sea corals—including primnoid coral ( Narella sp.), black coral ( Trissopathes pseudtristicha ), and feather stars ( Florometra serratissima )—flourish 2,669 m (8,757 ft) deep on...
Nudibranchs are a kind of sea slug, and their 3000 species are found from the poles to the tropics in both shallow and deep water. Though they often only reach two centimeters in length, they are...
This purple urchin Paleopneustes cristatus is seldom seen by itself, and can be found in groups of hundreds. Dr. Dave Pawson , a senior scientist at NMNH who studies deep-sea echinoderms, is testing...
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