Randomness: crab vision

I was going to post this to tnh's most recent open thread in Making Light, but her software and my browser aren't getting along.

Sitting in the physical therapist's waiting room and then office (my particular physical therapy involves a lot of sitting around while they apply electricity and then ultrasound to my shoulder), I read an article on the vision of some kind of crab. Natural History, I think April 2004, if anyone wants to try to track it down.

Basically, these crabs live in burrows in the mud. They have multi-faceted eyes on stalks, giving them a not-very-complicated view of everything above/around them. They seem to sort what they see into "above" and "at my own level". Any motion above the crab is preceived/treated as a predator (most likely a bird), and the crab retreats to its burrow. Motion at its own level is another crab, and the response will depend on how far the other crab is, how far the first crab is from its burrow, and whether it's looking for a mate.

Randomness: crab vision

I was going to post this to tnh's most recent open thread in Making Light, but her software and my browser aren't getting along.

Sitting in the physical therapist's waiting room and then office (my particular physical therapy involves a lot of sitting around while they apply electricity and then ultrasound to my shoulder), I read an article on the vision of some kind of crab. Natural History, I think April 2004, if anyone wants to try to track it down.

Basically, these crabs live in burrows in the mud. They have multi-faceted eyes on stalks, giving them a not-very-complicated view of everything above/around them. They seem to sort what they see into "above" and "at my own level". Any motion above the crab is preceived/treated as a predator (most likely a bird), and the crab retreats to its burrow. Motion at its own level is another crab, and the response will depend on how far the other crab is, how far the first crab is from its burrow, and whether it's looking for a mate.