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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 closures, or...
The ocean is home to a phenomenal diversity of marine organisms. They have...
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,...

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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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Giant squid live up to their name: the largest giant squid ever recorded by scientists was almost 43 feet (13 meters) long,...

The Ocean Blog

This rare staurozoan , or stalked jellyfish ( Haliclystus californiensis ) is about 2 centimeters in length and was collected off the coast of California. Unlike the traditional bell-shaped floating...
Seagrasses don't just provide shelter for free-swimming animals, but also are a habitat for non-moving organisms, such as this sea anemone. Sessile animals attached to blades are called epibionts,...
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...
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...
Sample the surprising diversity of deep-sea corals. See some of the ways they differ in color, shape, and size. Explore more in the multimedia feature " Coral Gardens of the Deep Sea ."
Bivalves brought up in a box corer from the deep Arctic seafloor.
Stinging cells (nematocysts) line the tentacles of this moon jelly ( Aurelia aurita ). Upon contact with prey or a predator, a venom-laden harpoon shoots out to stun or kill. Read more about...
Many jellyfish in the class Hydrozoa, such as this hydromedusa Aglantha digitale , are transparent and easily overlooked. Learn more about hydrozoan jellies and other jellyfish , and see more...
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...
The largest of the cuttlefish species, Australian Giant Cuttlefish ( Sepia apama ) delight scientists each year as they gather in masses to spawn in northern Spencer Gulf, northwest of Adelaide in...
The blue lined octopus may be small, growing to at most 15 cm, but it can be deadly: its venom can cause breathing failure in humans as well as other animals. Turtles can accidentally consume the...
Several species of amphipod like this one, Gammarus wilkitzkii , live permanently within Arctic sea ice . These animals are endemic, meaning they only live here. They acclimate to a wide range of...
In recent years, blooms of jellyfish, such as these moon jellies ( Aurita aurita ) in the Chesapeake Bay, have become more common around the world for a number of different reasons . One result of...
A mangrove tree crab ( Aratus pisonii ) clings to a leaf near the Smithsonian Institution’s marine laboratory on Galeta Island, Panama, part of the Smithsonian Tropical Research Institute . During...
Last week, Smithsonian research zoologists Dr. Jerry Harasewych and Dr. Martha Nizinski were in Curaçao looking for deep-sea marine gastropods and decapod crustaceans , respectively. I learned they...
Some of the most otherworldly animals—like those straight from a science fiction story—can be seen in the open ocean at night. By drifting in the blackwater in a scuba suit just under the surface,...
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 .
The blanket octopus can rip a poisonous tentacle from a Portuguese man-o-war and wield it like a sword to ward off enemies as it soars through the ocean trailing its webbed cloak behind it...
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