Crayfish remember each others' faces!

[Squawkbert]

http://www.msnbc.msn.com/id/23502348/

excerpt:
By Charles Q. Choi

updated 24 minutes ago
You looking at me, crayfish face?

It seems that crayfish don't forget a face — at least, not those of their foes.

Australian crayfish, also known as Cherax destructor, usually fight when they meet. After observing some such clashes, researchers isolated losers and gave them a choice between their former opponents — the faces of which scientists dabbed with yellow dye — and unpainted crayfish they had not fought before. The researchers found the losers preferred the opponents they knew rather than the rival they did not, revealing the crustaceans recognized faces. "This suggests they are looking at each other more than we thought," said researcher Blair Patullo, a zoologist at the University of Melbourne in Australia.

[vampie]

Or maybe they just really hate yellow paint?

[Dwarf Puffers]

I'd guess they'd look at the big muscled guy with intimidating colors and a crayfish they'd never seen and think... Hey, I'll go with Mr.Normal over there.

Are they taking size into affect? Obviously a bigger cray is going to be more intimidating. They could also take the color as a sign of dominance, like how dominant female bettas display the most color.

[Squawkbert]

Paint or no paint, bigger or not, they'd rather fight with one that's kicked their butt before than a stranger.... The devil you know, I guess - or they're both optimistic and vindictive.

[Notophthalmus]

I hope the study was more thorough than that article revealed. For example, what makes them think the crayfish are using visual, rather than chemical, cues to recognize one another?

[Robin Alv]

Good point about the cues. I do believe there are "cues" - But I do wonder what made them decide the cue was visual??? Interesting -

[pixl8r]

Crayfish do have excellent eyesight, which has been confirmed via experimentation. I don't have the scientific papers handy, but I'll look and post a synopsis of how it was proven. I also see it with my own Cherax crayfish. When I come into the room he moves close and challenges me. And I use a stick to give him treats (since he got big enough to take of a finger with his claws). If I put the stick in the water without a treat, he still goes for it the same as if I had put a cube of boiled chicken on it.

But, I can't say that they use visual cues to recognize each other, or not.

In either case, it's a very interesting post. I particularly laughed at the twins reference. I have childhood friends who used to 'assume' each other's lives. I could only tell them apart when I saw them walk.

[FtwayneFish]

My crays would do the same^ always ready when I was in the room.