Friday 10 February 2012

Stalked Jellyfish

Image: Wikipedia
Stalked Jellyfish? What? It may seem strange but there really is such a thing as a jellyfish with a stalk. They have abandoned the usual life of swimming with the sea's most graceful wobble and have instead opted to attach themselves to the floor and stay there.

The 50 or so species of Staurozoa range between a few millimetres to 15 cm in height. Most come from cold, coastal environments in the northern hemisphere, but some explorers find themselves around Antarctica and the biggest ones come from the deep sea.

Image: California Academy of Sciences
Their affinity to the floor starts right at the beginning. You might remember how jellyfish start out as a tiny planula that swims using hair-like cilia. Stalked Jellyfish are similar, except their planula have no cilia and creep along the ground like a slug. There'll be no care-free drifting for them, they got to get to work finding a nice site to set up home.

Their usual place of residence are stones, algae, eelgrass and the like. The planula attaches itself and grows into a polyp just like the usual jellyfish. But they don't go through strobilation, where the polyp segments into a stack of tiny jellyfish. Instead, the whole polyp matures into an adult and remains attached to their surface.

Image: California Academy of Sciences
They end up as a strange mixture of Crinoid and Sea Anemone. They have 8 arms, each tipped with a pom-pom of tentacles for catching small crustaceans. The whole creature looks like quite a nice, decorative goblet, or you could turn it around and turn it into a fancy light fitting. Or maybe just leave it where it is. Up to you.

Just like Sea Anemones they can slowly slide along the floor to find better situations, but some of them have sticky tentacles so that they can somersault their way to pastures new. Some even have to do this because the youngsters live on algae that can't actually support their weight when they approach adulthood. You wouldn't have thought a jellyfish could have an adolescence full of difficult upheavals, but they have managed to find a way.

Image: California Academy of Sciences
Reproduction is achieved by the tried and true method of chucking all your stuff out and letting them get on with it. For such lovely little flowers as these I'm willing to consider it some kind of "sea-swept pollination", but just this once and only because it's you.


Emily said...

These are beautiful!

Joseph JG said...

I agree! Whenever I think of jellyfish I just don't think they "should" be nice to look at, but here's a whole other kind of jellyfish that has found a whole other way of being pretty!

TexWisGirl said...

really pretty! like coral and jellyfish had a baby!

Joseph JG said...

Haha! You're right! I hadn't thought of that.

Anonymous said...

They look totally like flowers, especially when they are attached to a plant!

Well, now I know that I should not touch them, put them in a vase and definitely not smell them afterwards.

Joseph JG said...

Yup! Stinging tentacles up the nasal passages is best avoided.