Friday Parasite: Parasitic Jellies

As adults, lined sea anemones (Edwardsiella lineata) look very much like any other sea anemone – tentacled, flowerlike polyps that hold onto the ocean floor and grab meals from whatever happens to blunder in reach. But as youngsters, they’re far less benign, at least if you happen to be a ctenophore. In most anemones, spawned eggs and sperm fuse to form free-living planula larvae that eventually settle and metamorphose into adult anemones. Lined sea anemones do things a little differently -- their planula larvae find ctenophores of the species Mnemiopsis leidy and parasitze them.

How does it work? First, E. lineata larvae dig into a ctenophore and take up residence in its body wall. Once there, they develop wormlike bodies and stick their mouths  into the ctenophore’s digestive cavity. They then proceed to suck up nearly all the food the ctenophore collects for itself. Obviously, this is not terribly good for the ctenophore – infected individuals stop growing and may even shrink in size. Eventually, the larval anemones leave the ctenophores and settle to the ocean floor to become adults.


References:
Bumann D. and G. Puls 1996. Infestation with larvae of the sea anemone Edwardsia lineata affects nutrition and growth of the ctenophore Mnemiopsis leidyi. Parasitology 113: 123-128.

Reitzel, A. M., J. C. Sullivan and J. R. Finnerty 2006.  Qualitative shift to indirect development in the parasitic sea anemone Edwardsiella lineata. Integ. Comp. Biol. 46(6): 827-837.

Photo from the Finnerty Lab, Boston University

And a tip of the hat to Stan Rachootin, for letting me know about this parasite!

Comments

[Cambias]

So for the ctenophore, this is:

an enemy anemone?

[Eric]

Wow, thanks for highlighting this great relationship!

My son's first marine biology experimnet was to see what was bioluminescing in the Mystic CT. estuary, we collected a number of organisms, but M. leidyi, was among them (and as he discovered the caue of the bioluminescence). Most of the individuls had the pink vermiform larvae in them, serveral had more than one, and one had 6 individual parasites (similar to the picture above!).

[Benj]

Thanks for this post, I was precisely wondering if there were parasites among the Cnidaria phylum... so it seems!

By the way would you be aware of parasitic species in the Echinodermata of Bryozoa phyla?

Thanks again, best regards.