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The Ocean Blog

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...
Using an ROV (Remotely-Operated Vehicle) equipped with a high-definition video camera, scientists can observe the life that flourishes beneath the Arctic ice . On this expedition, they discovered...
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...
Chrysaora melanaster , one of the largest jellyfish commonly found in the Arctic, swims underneath the Arctic ice . Its tentacles can stretch to more than 3 meters long and pack a mean sting for...
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...
Found in the icy waters of the Arctic , Comb Jellies, or ctenophores like this one, of the Aulacoctena genus, are poorly known animals. With extremely fragile bodies, they are difficult to capture...
How long have jellyfish lived in the ocean? This jellyfish fossil is from the Cambrian period, more than 500 million years ago. It was found buried in Utah —an area that used to be underwater,...
What does a bioluminescent creature that lives more than 2 miles below the surface of the ocean and a glow stick have in common? More than you think. Bioluminescence is the process by which living...
The lion’s mane jellyfish ( Cyanea capillata ) is the largest among the jelly species, with the largest known specimen stretching across 120 feet (36.5 meters) from its top to the bottom of its...
This colony of Rosacea may look like a single jellyfish, but it is actually a large group of smaller siphonophores clustered and living together. In fact, the zooids (individual siphonophores living...
Throughout their lifecycle, jellyfish take on two different body forms: medusa and polyps. Polyps can reproduce asexually by budding, while medusae spawn eggs and sperm to reproduce sexually. Learn...
Jellyfish and comb jellies are gelatinous animals that drift through the ocean's water column around the world. They are both beautiful—the jellyfish with their pulsating bells and long, trailing...
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...
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...
Since late April, the world has watched a devastating oil spill from a BP drilling rig spread throughout the Gulf of Mexico and become one of the worst environmental disasters in the history of the...
Sea jellies such as this one in the genus Benthocodon are commonly seen on or near the seafloor in the Monterey Canyon off central California. Some jellies in this genus feed on animals that live in...
Atolla tenella , a midwater scyphomedusa , as seen under a microscope. View the “Under Arctic Ice” photo essay to learn more.
"Inside the Open Ocean: Blue Water Diving" produced by Woods Hole Oceanographic Institution (WHOI) , describes a specialized diving technique that lets biologists study the ocean's most fragile...
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