Ramisyllis multicaudata is an animal that seems to have adopted the lifestyle of a fungus
If you had 1,000 butts, what would you do with them? The marine worm Ramisyllis multicaudata is one of only two known animals to find itself in this rather awkward situation-and it isn't yet telling.
Ramisyllis is a bristle worm that lives inside the water passages of a sponge called Petrosia in a shallow reef off the coast of northern Australia.
One "Small" sponge observed by scientists was festooned with more than 100 crawling worm fannies, sometimes more than 10 to a single opening.
What makes these worms particularly interesting to me is that they appear to be an animal that has adopted a fungal lifestyle.
It's been known for a while that soft-bodied marine invertebrates can absorb dissolved organic matter directly from seawater through their "Skin." But Ramisyllis may have taken this to the next level: the anatomy team discovered the worm's body is also suspiciously covered in long microvilli.
Just in front of it lies the polychate worm version of the apical meristem in plants: a place where stem cells continuously generate new body parts called the posterior growth zone.
Polychaete worms have these in order to make new segments.
The group to which these worms belong-the syllids-are perhaps unique among bilaterally symmetrical animals in this bizarre reproductive strategy, termed "Gemmiparous schizogamy." Certain insects, of course, do something similar in that they produce ephemeral adults whose sole aim is to knock extremely tiny, extremely urgent boots, but they generally live as larvae for a much longer period.
The image of a Ramisyllis stolon amidst the branches of its generative worm is strikingly similar to photographs of the fungus Fusarium bearing its distinctive boat-shaped spores.
If their whole bodies can absorb dissolved food, why is there such an emphasis on all the myriad backsides reaching the surface of the sponge? In one specimen dissected by scientists, bunches of worm butts were found stuffed into sponge cul-de-sacs.