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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...
What reef animal comes in a rainbow of crazy colors, can throw out its stomach...
This summer, many of you have likely enjoyed feasting on crabs, be they blue,...
About 100 million years ago , during the heyday of the dinosaurs, reefs were...

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The sea hare gets its common name from its equivalent of nose and tongue—external sensory organs for smell and taste called rhinophores—which look like bunny ears. The sea hare, however, doesn't hop like a rabbit: it is a sea...
“Upon returning from the reef after a night dive, I swam toward a bright...
This ctenophore (a stingless jellyfish-like animal) is native to the east...

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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

A chambered nautilus shell.
This red octopod ( Stauroteuthis syrtensis ) shines in a novel way. Suckers stretching in a single row down each arm flash on and off. The glowing-sucker octopod drifts through deep waters off the...
Seahorse couples, such as this pair of thorny seahorses ( Hippocampus histrix ) , greet each other every morning with a unique dance that sometimes involves changing color. The couple promenades and...
Even on an early winter morning, it was sunny and warm in southern Florida. This was great because, regardless of the weather, Dr. Jon Norenburg and I were going to walk chest-deep into the water to...
The ROV Hyper Dolphin caught this deep-sea jelly (Atolla wyvillei) on film east of Izu-Oshina Island, Japan. When attacked, it uses bioluminescence to "scream" for help—an amazing light show known as...
Hermit crabs, like this one collected in Moorea, usually protect their soft, vulnerable abdomens from predators by reusing empty snail shells. They are picky home owners and they will trade shells...
A cameraman navigates a smack of sea nettles ( Chrysaora fuscescens ) in Monterey Bay. A group of jellies is known as a "smack."
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...
A specimen from the Smithsonian’s squid collection and videos of a mystery squid helped scientists identify a new family of deep sea squid—the Magnapinnidae, known as the bigfin squids. More about...
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...
This male giant squid is on display in the Sant Ocean Hall at the Smithsonian’s National Museum of Natural History . It measures about 2.7 meters (9 feet) long and weighs a little more than 45.5...
The festive Christmas tree worm ( Spirobranchus giganteus ) lives on tropical coral reefs and resembles a fluffy fir tree adorned with ornaments. The multi-functional branch-like appendages are used...
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...
This bivalve mollusk is native to the Caspian Sea, lagoons of the Black Sea, and their inflowing rivers. It lives in fresh and brackish water and cannot tolerate full seawater. In the 18th and 19th...
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...
Not all slugs (snails without shells) are slimy brown pests found in your backyard garden. In the ocean they come in a huge variety of colors — some match the background and are hard to spot, but...
“It is strange to think of a sea turtle as an ecosystem,” says Amanda Feuerstein, program coordinator and research assistant at the Smithsonian’s National Museum of Natural History, “but they are…...
Come along as scientist Dr. Brendan Roark narrates a submersible dive to collect and study deep-sea corals. Roark studies deep-sea corals to understand the history of the ocean and past ocean...
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