The Medusa and the Snail
by
Lewis Thomas

"We've never been so self conscious about our selves as we seem to be these days."

p. 1.

Sometimes there is such a mix-up about selfness that two creatures, each attracted by the molecular configuration of the other, incorporate the two selves to make a single organism. The best story I have ever heard about this is a tale told of the nudibranch and the medusa living in the bay of Naples. When first observed, the nudibranch, a common sea slug, was found to have a tiny vestigial parasite, in the form of the jellyfish, permanently affixed to the ventral surface near the mouth."

In curiosity to learn how the medusa got there, some marine biologists began searching the local waters for earlier developmental forms, and discovered something amazing."

The attached parasite , although apparently so specialized as to have given up living for itself, can still produce offspring, for they are found in abundance at certain seasons of the year. They drift through the upper waters, grow up nicely and astonishingly, and finally become full grown, handsome, normal jellyfish. Meanwhile the snail produces snail larvae, and these too begin to grow normally, but not for long.

While still extremely small, they become entrapped in the tentacles of the medusa and then engulfed within the umbrella shaped body. At first glance, you'd believe the medusa are now the predators. Paying back for earlier humiliations, and the snails the prey. But no. Soon the snails, undigested and insatiable, begin to eat, browsing away at the radial canals, then the borders of the rim, finally the tentacles, until the jellyfish becomes reduced in substance by being eaten while the snail grows correspondingly in size.

At the end, the arrangement is back to the first scene, with the full grown nudibranch (marine snail) basking and nothing left of the jellyfish except the round, successfully edited parasite, safely affixed to the skin near the mouth."

"It is a confusing tale to sort out, and even more confusing to think about."

"...they cannot live in any other way; they depend for their survival on each other. They are not really selves, they are specific others."

pp. 3-4

"...they remind me of the whole Earth at once."

p. 5.