Invertebrates

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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 the water with their...
Since summer 2013, starfish along both coasts of the United States have been...
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Tiny plant-like organisms called zooxanthellae live in the tissues of many...
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I have been at the Smithsonian’s National Museum of Natural History since 1966...

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Census of Marine Life researchers discovered this unusual transparent sea cucumber ( Enypniastes sp.) in the Gulf of Mexico at 2,750 meters depth. It creeps forward on its tentacles pretty slowly, at around 2 centimeters per...
Smaller than the head of a pin, this arrow squid (Doryteuthis plei ) embryo...
Anemones are known for serving as homes for Nemo and countless other small...

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Jellyfish and comb jellies are gelatinous animals that drift through the ocean's water column around the world. They are...
This close-up view of salps, which have aggregated together into a long chain, have brilliant red guts from eating red plankton. They were observed by researchers with the Census of Marine...
This octopod is sometimes called a “Dumbo” octopod because its fins resemble the ears of Disney’s Dumbo the elephant. The video was recorded in 2003 on the Mid-Atlantic Ridge by the Russian manned...
Instead of females, male seahorses carry the developing seahorse embryos in a kangaroo-like pouch. During mating season, the female deposits her eggs into the pouch, and the male fertilizes them...
Marine biologists from MBARI nicknamed this startlingly large jellyfish—which grows over one meter (three feet) in diameter—"big red." It would be hard to miss, except that it lives at depths of 650...
Glowing photophores are visible on this midwater squid ( Abralia veranyi ) viewed from below at low light levels. We think of light as a way to see in the dark. But many species use it to help them...
Seahorses are not just tropical creatures. They can be found in colder waters like those found off New Zealand, Argentina, Eastern Canada, and the UK. This long-snouted seahorse ( Hippocampus...
I have a vivid childhood memory of sitting under the Blue Whale model hanging in the Natural History Museum in London, eating an ice cream and wondering “How in the world did that whale get so big?”...
This image from a scanning electron micrograph magnifies the tiny teeth that cover the surface of the giant squid’s tongue-like organ, or radula . Seven rows of sharp teeth help direct tiny pieces of...
This pair of sea butterflies ( Limacina helicina ) flutter not far from the ocean's surface in the Arctic. Sea butterflies are a type of sea snail, but instead of dragging themselves around the...
Many expeditions in the Arctic reveal new species, such as this jellyfi sh Bathykorus bouilloni , which, strangely, has only four tentacles! Dr. Kevin Raskoff from California State University,...
Small amphipods, the blue bug-like creatures, can be seen here catching a ride on this enormous sea spider as it makes its way across the bottom. Many Antarctic creatures, like the dinner-plate-sized...
This swimming crab ( Liocarcinus holsatus ) has a parasitic barnacle rooted in its reproductive system. This invasion cuts off all reproduction for an infected crab and can even cause a male crab to...
Atolla tenella , a midwater scyphomedusa , as seen under a microscope. View the “Under Arctic Ice” photo essay to learn more.
This female hyperiid ( Phronima sedentaria ) is surrounded by her young, residing in the hollowed out barrel-shaped body cavity of a salp. It is thought that the mother Phronima captures and kills...
Isopods (small, shrimp-like animals) like this one ( Gnathia aureusmaculosa ) are the mosquitoes of the sea, sucking the blood of fish while they sleep. Find out more in " No Fouling Around " from...
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...
In the Coral Triangle, a biodiverse area between Indonesia and the Philippines, scientists discovered this swimming polychaete (bristly worm), which they have dubbed the "squidworm." Using a remotely...
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