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Marine Monday: Stalked Jellyfish

A stalked jellyfish. [Image via Wikimedia Commons.]

You’ve probably seen pictures of jellyfish floating gently through the water, but did you know that some jellyfish spend most of their lives in one spot?

Stalked jellyfish, which are funnel shaped, with eight legs joined by membranes surrounding a mouth, are one example. Only an inch or two tall, they live in cold shallow water in the North Pacific.

When stalked jellyfish mature, they attach themselves to a piece of seaweed or eelgrass with an adhesive disk. Scientists believe they might be able to basically cartwheel short distances, but for the most part, they are sessile – meaning they stay in the same place.

Because stalked jellyfish can’t follow prey, they use their tentacles to catch small fish and shellfish, although they have to spit out shells, as they’re too difficult to digest.

Although adult stalked jellyfish cannot eat large prey, immature jellyfish, called planula, have developed a collaborative approach to offer more dining options. At this point in their lives, the jellyfish are mobile, so while they can’t kill by themselves, they can gang up on rotifers, nematodes, copepods, and other ocean snacks.

Stalked jellyfish are also notable for having relatively developed nervous systems compared to their relatives.

You can learn more about stalked jellyfish from Oceana’s marine wildlife encyclopedia.


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