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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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Ultraviolet light illuminates the growth rings in a cross-section of a 44-year-old deep-sea coral ( Primnoa resedaeformis ) collected off the coast of Newfoundland at about 1,300 feet (400 meters). Similar to tree trunks, cross-...
A “pink meanie” jellyfish ( Drymonema larsoni )—a species found in the Gulf...
This brilliant red octopus ( Benthoctopus sp. ) was photographed at more...

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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...
Weighing 600 pounds (around 272kg) and having a 30 foot (around 9 meters) arm span, the largest recorded giant pacific octopus was truly enormous. Giant pacific octopuses are powerful predators that...
Claws, spines, spikes, tentacles, and fangs. Aliens, monsters, and ghostly apparitions glowing in the night. Marine life forms have some of the best looks for Halloween—no costumes needed. From...
This copepod Calanus hyperboreus (up to 7mm in length) lives in the Arctic , usually within 500 meters of the surface. To survive the cold Arctic winters, Calanus hyperboreus builds up dense fat (...
The feathery strands at the back of this nudibranch’s ( Chromodoris willani ) body are no mere adornment: they’re its gills! Nudibranchs, shell-less snails or sea slugs, are named for these tufted...
Ochre seastars ( Pisaster ochraceus ) feed on invertebrates, such as coral and shellfish, like the mussels pictured here. The starfish forces open the shell with suction disks on the underside of its...
The mauve stinger’s ( Pelagia noctiluca ) name in German means “night light,” referring to the jelly’s reddish coloring and its bioluminescence, the display of light by a living creature. Unlike a...
Bioluminescence is one of the more captivating adaptations that have evolved in marine animals. It's the ability of organisms to create and emit light. Dive underwater and you may witness lightshows...
Polarized sunglasses have become the norm for humans when they want to filter out the strong glare from the sunlight bouncing off of water in a horizontal direction. But how do animals do that live...
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...
In this photo of a shallow coral reef in the Pacific there are three species of forams . On the left, Peneroplis planatus . In the center, Amphistegina lessonii . And on the right, Laevipeneroplis sp...
This tan urchin, Conolampas sigsbei , is one of only two known deep-sea urchins that cover their tops with small rocks and shells. Many shallow species cover themselves for reasons that have been...
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...
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...
This jelly’s red color provides camouflage in the deep ocean. Red light rarely reaches those depths, and most deep-sea animals have lost the ability to see red. The long, complex tentacles of this...
Fitting nine of anything on two fingers is impressive. These mollusks and echinoderms are a teeny-tiny sample of the ocean's biodiversity. The Census of Marine Life estimates that there are at least...
The sargassum is coated with encrusting organisms, such as bryozoans and hydroids, that use it as a perch to filter feed in the oceanic waters, as well as crustaceans such as thos swimming crab...
Like other cephalopods, the common cuttlefish ( Sepia officials ) is no dummy. But while octopuses are quick to learn manual tasks like opening jars, cuttlefish have a different skillset: the social...
A sea monster attacks a ship in an illustration for 20,000 Leagues Under the Sea by Jules Verne. The illustration is by publisher and artist Pierre-Jules Hetzel, who is most famous for his drawings...
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