There's no such thing as a jellyfish

By all accounts, jellyfish are creatures that kill people, eat microbes, grow to tens of meters, filter phytoplankton, take over ecosystems, and live forever. Because of the immense diversity of gelatinous plankton, jelly-like creatures can individually have each of these properties. However this way of looking at them both overstates and underestimates their true diversity. Taxonomically, they are far more varied than a handful of exemplars that are used to represent jellyfish or especially the so-called "true" jellyfish. Ecologically, they are even more adaptable than one would expect by looking only at the conspicuous bloom forming families and species that draw most of the attention. In reality, the most abundant and diverse gelatinous groups in the ocean are not the ones that anyone ever sees.

To report sightings of jellyfish and other marine organisms, go to http://jellywatch.org/

• Category

  Science & Technology

[Cathal Brown]

What is the name of the jellyfish with tentacles pointing ahead of them

at 1:36

[MBARIvideo]

The Narcomedusae are the jellies whose tentacles point ahead of them instead of pointing behind like most jellies. The little yellow one in the video with 4 tentacles pointing ahead is called Aegina citrea.

[David Knox]

Hello, I loved the video. The question I have had for ever is how do the jellys produce that pulsating rhythmic movement? I imagine it is not a nerve impulse to muscle cell activation mechinism, so what is it?

[MBARIvideo]

A jellyfish has a ring of muscle around its bell. When a jellyfish tightens this muscle, its bell closes. This pushes water inside the jellyfish out, shooting the jellyfish forward. As the muscle relaxes, water refills the bell. This is how they pulse in the water. Each tentacle can be moved by its own muscles, as can the oral arms. Jellies have a nerve ring that connects the rhopalia (sensing organs) and a nerve net that can send messages around the bell to contract and release.

[David Knox]

Cool , so there is a connection through the nerve ring from sensing organs to oral arms , bell and tentacles, without the need of a brain allowing the jelly to respond to environmental stimuli ?

[MBARIvideo]

Exactly!

[Simpsonsfreak1134]

There's also no such thing as a fish. Biologically speaking a salmon has more in common with a camel then it does with hagfish.

[Nekura Neko]

They're all so pretty ;O

[selfatrophy]

Cool jellyfish.

[BradShaw1690]

Zzzzzzzzzzzzzzzzzzzzz

[KeivanHH]

I didn't expect there was such a variety of jellyfish... This video is amazing!

[Oceanrust4]

There's no such thing as things.

[ScythesBlade]

well then, there's no such thing as a bird, snake, whale, or shark, either... from what I've seen, you've just been calling jellyfish by their scientific names, and saying "They aren't jellyfish!"

[CaptainCarthex]

Wait where does jelly come from?

[tsdiggs78]

The ones with the different color lights look cool

[boredguy52]

I thought the common red and blue coloration was because those colors "disappear" in various deep levels of water because of the frequency of the light waves.