Box Jellyfish Have “Quite Sophisticated” Eyes, “Not So Different From Our Own”

Oliver Sacks at the New York Review of Books writes on the mental life of “plants and worms, among others,” and it is a wonderful science essay that completely buries the jellyfish lede:

In the 1880s, however, despite Agassiz’s and Romanes’s work [defining the role of synapses as they relate to organism function], there was still a general feeling that jellyfish were little more than passively floating masses of tentacles ready to sting and ingest whatever came their way, little more than a sort of floating marine sundew.

But jellyfish are hardly passive. They pulsate rhythmically, contracting every part of their bell simultaneously, and this requires a central pacemaker system that sets off each pulse. Jellyfish can change direction and depth, and many have a “fishing” behavior that involves turning upside down for a minute, spreading their tentacles like a net, and then righting themselves… If bitten by a fish, or otherwise threatened, jellyfish have an escape strategy — a series of rapid, powerful pulsations of the bell — that shoots them out of harm’s way; special, oversized (and therefore rapidly responding) neurons are activated at such times.

Of special interest and infamous reputation among divers is the box jellyfish (Cubomedusae) — one of the most primitive animals to have fully developed image-forming eyes, not so different from our own.

Box jellyfish have “retinas, corneas, and lenses.” Box jellyfish: they’re just like us. Box jellyfish: *faints* [NYRB]