Some beasts were meant to have eyes; some were not. Starfish, which already operate in that terrifying and nebulous shadow world of animals who behave like plants (oddly enough, these are more frightening than plants that behave like animals), were not meant to. A starfish is a mouth wrapped in a hand. A starfish is a waking nightmare that moves by hydraulics. They are already sentient, living hands with a mouth at the center that spend their lives clinging remorselessly to reefs and aquaria capable of regenerating at will; they do not need dim and dawning eyes furrowing about at the end of their limbs. And yet they have. And yet they have.
Despite the confirmation of sea star sight, the animals won’t be developing reputations for great vision any time soon.
“The image formed in the starfish eye is a very crude image,” says study co-author Garm. “It only has about 200 pixels.”
But it’s enough to enable the blue sea star to recognize large, immovable structures, he said.
This species is tightly tied to coral reefs. If it wandered off to the sandy flats surrounding those reefs, it wouldn’t be able to find food and would eventually starve.
How does one wipe the sensation of eyes and horror off of one’s limbs? Tell me no more; I cannot bear it, I cannot bear the thought of crawling eyes along the sea floor.
Starfish have compound eyes, like the ones on arthropods such as insects or lobsters, but the resemblance ends there, Garm says. For instance, blue sea star eyes lack lenses, unlike arthropods’ eyes.
GOOD GOD. Lenseless lobster eyes, flailing half-blindly, dimly groping their way along a reef, longing for home, unprotected from grit and flotsam, grotesquely searching out for it knows not what.
Garm and colleagues combined physical measurements of the eye itself with behavioral experiments to come to their conclusions.
One such measure gave researchers an idea of how wide the sea star field of view was: large enough to pick out a coral reef in front of them.
“Home,” the eye-hand-mouth ball gasps, dragging itself further along the sand. “Home.”
Their behavioral observations involved moving individual blue sea stars off of a coral reef near Okinawa, Japan, to see if the animals could make their way back or not.
Starfish displaced about three feet (a meter) from the reef walked back home in pretty much a straight line. But animals placed either six feet (two meters) or 12 feet (four meters) away ended up wandering around randomly.
Starfish placed three feet (a meter) away from their reef at night also wandered around randomly, most likely because they couldn’t see the reef, said Garm.
Merciful heaven, don’t anger them. Don’t rip them from the only home they know just to test their eyes, you fools. If they can see, they can remember. If they can remember, they can take revenge. A sea floor riddled with bumbling, irritated, lost and wandering starfish capable of seeing through a glass but darkly is the last thing this troubled planet needs.
“The large sunflower star (Pycnopodia helianthoides) found on the Pacific coast is a fast and efficient predator which is often observed to chase down and swallow its food,” he said. Mah would love to know whether vision plays a part in this large animal’s ability to capture food.
Garm and colleagues have their sights set on a large starfish species, but not the sunflower star.
Instead, Garm plans to look at the visual system in the crown-of-thorns sea star (Acanthaster planci), responsible for devouring major areas of coral reefs off the coasts of Australia and Asia.
“It’d be nice to [know] if they use vision to see the reef,” Garm said. He hopes to use the information to potentially protect areas like the Great Barrier Reef from this voracious predator.
There are some things we do not need to know; turn away before you learn something you cannot unlearn. Nothing named after a crown of thorns need be meddled with. It eats reefs. It devours coral and petrified rocks and the frozen corpse of calcareous algae dead since time immemorial. Let me set your mind at ease now: it can see. Oh, gods, it can see. Go back. Go back to your wife and your sweet children and your bed at night, and thank God for the sunlight in your own life, and meddle not with the eyes of the writhing hand-mouths of the deep sea.
Mallory is an Editor of The Toast.