Invertebrates

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Watch as barnacles feed on bioluminescent dinoflagellates. Barnacles are crustaceans (like crabs, shrimps and lobsters) that secrete their shells for protection while living attached to things like rocks, harbors or boat hulls. They feed...
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Depending on whom you talk to, jellyfish are either fascinating, a nuisance, a...
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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,...

LATEST CATCH

For a long time, scientists thought that some small tentacled fossils were early ancestors of jellyfish. But a new study has found that these ancient animals are actually related to an entirely different group of animals : the...
This swimming crab ( Liocarcinus holsatus ) has a parasitic barnacle rooted...
In 2006, this female giant squid attacked bait suspended beneath a Japanese...

DIVE DEEPER

Jellyfish and comb jellies are gelatinous animals that drift through the ocean's water column around the world. They are...
Simon Coppard, a post-doctoral research fellow at the Smithsonian Tropical Research Institute in Panama and an Encyclopedia of Life Rubenstein Fellow specializing in echinoids often uncovers new...
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...
Last September, the Citizens of the Sea blog series brought you a story of doom and gloom from the reefs of Bocas del Toro, Panama. That is the time of year we typically study -- and celebrate -- the...
Ocean scientists discovered this 1.5-m (5-ft) tall yellow bamboo coral in 2007 off the coast of Hawaii in 1,459 m (4,787 ft) of water. It is thought to represent a new genus. Learn about more deep-...
Chrysaora melanaster , one of the largest jellyfish commonly found in the Arctic, swims underneath the Arctic ice . Its tentacles can stretch to more than 3 meters long and pack a mean sting for...
Deep sea animals have to live in a very cold, dark, and high-pressure environment where they can't see a thing! To survive there, they've evolved some very strange adapations. Some make their own...
An isopod stands on top of a glass sponge, extending its legs to find zooplankton. This delicate sponge is small, but some glass sponges can grow to the size of a 50-gallon drum and live for...
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...
Seahorses range in size—from as small as a pine nut to as large as a banana. The largest seahorse species (pictured here) is Hippocampus abdominalis , or the big-bellied seahorse, which can reach...
The jingle shell ( Anomia simplex ) is a common bivalve found on the Atlantic coast of North America, amongst the more commonly known clams and oysters. As with oysters, the lower shell is glued to a...
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...
On many of the dives, Oceana's 2011 Baltic Sea expedition team saw little wildlife in the oxygen-depleted areas. But near some marine protected areas, the crew saw an array of marine life, including...
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...
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...
A mass of white muscle the size of a softball surrounds the dark brown beak of a giant squid. Learn more about this animal's oversized anatomy in our Giant Squid section .
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...
Coral reefs are the most diverse of all marine ecosystems. They teem with life, with perhaps one quarter of all ocean species depending on reefs for food and shelter. This is a remarkable statistic...
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 .
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