The Brittle Star That Sees with Its Body

[Judi Lynn]

It turns out that eyes aren’t necessary for vision

By Jennifer Frazer on July 28, 2020



The long, squiggly arms of a brittle star—a relative of the sea star with baroque tendencies—have a surprising relationship with the rest of its body.

Its arms function more or less independently, sensing their own environment and making their own decisions about how to react to it. They are only loosely coordinated by a nerve ring in the animal’s core. A single brittle star is almost like five co-joined animals with a mutual interest in where to go, what to eat and making little brittle stars.

And yet now there appears to be something far stranger about the biology of at least one species: the entire body of Ophiocoma wendtii appears capable of forming a blurry but serviceable image, like a squirmy but strangely cute Eye of Sauron.

It gets weirder.

This full-body vision is extinguished at night, when the animal’s sensitivity to light paradoxically increases, and its maroon body turns beige. How and why this animal possesses these strange characteristics were the subjects of a study published in January in Current Biology.

More:
https://www.scientificamerican.com/article/the-brittle-star-that-sees-with-its-body/