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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

These corals from the Smithsonian collections are Stephanocyathus (A.) spiniger , a solitary, deep-water stony coral species. Around 74% of all deep-water corals are solitary, living as individual...
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...
This magnified photo provides a close-up look at copepods—tiny crustaceans that right whales feed on. There are many species of copepods that live throughout the water column, from floating at the...
It's a pygmy seahorse ( Hippocampus bargibanti ), found in Indonesia's biodiverse Coral Triangle and one of the smallest seahorse species in the world! They can change colors like a chameleon to...
Dr. Clyde Roper prepares to dive thousands of feet to a giant squid habitat off the coast of New Zealand in a one-person submersible. More about the giant squid can be found in our Giant Squid...
Dr. Clyde Roper, squid expert, explains how he developed a passionate interest in the giant squid ( Architeuthis dux) in this excerpt of "Eyeball to Eyeball," an episode of Errol Morris' First Person...
Researchers use Autonomous Reef Monitoring Structures (ARMS) like this one to study the diversity of coral reef organisms. They leave the structures underwater for about a year. Then they retrieve...
Two brown and purple nudibranchs ( Risbecia tryoni ), crawling in tandem on a surface encrusted with pink-colored coralline algae. These "sea slugs" live in the tropical Western Pacific Ocean. You...
These large jellyfish ( Chrysaora fuscescens ) are most commonly found along the coasts of California and Oregon. (They're also popular in the displays of public aquaria.) Their bells can grow to a...
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...
This bearded fireworm ( Hermodice carunculata ) must have a strong stomach -- it’s sucking on fire coral ( Millepora sp. ), which would give the unlucky snorkeler a nasty sting. Encountered in St...
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...
Dr. Clyde Roper (top left), of the Smithsonian Institution, and scientists from NOAA and the Delaware Museum of Natural History dissect a giant squid specimen donated by NOAA. Everything we know...
Giant anemone. More about mangrove ecosystems can be found in the Mangroves section .
Dr. Martha Nizinski holds a specimen of a fan sponge ( Phakellia sp. ) collected at a deep-sea coral study site off the coast of South Carolina. Deep-sea corals and sponges provide structure for a...
Riftia tubeworm ( Riftia pachyptila ) colonies grow where hot, mineral-laden water flows out of the seafloor in undersea hot springs—such as the Guymas Basin of the Gulf of California at 2,000 meters...
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...
Giant clams are one of the many wonders of coral reefs. They can grow up to five feet wide, weigh over 400 pounds, and live for 100 years! They power all that bulk by filter feeding microbes and...
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