crayfish
Posted by Larry Chambers on April 3, 2006
Q: Do crayfish have gills?
Why are they able to stay out of water so long?
How do you sex crayfish?
Thank you,
Larry
A: Crayfish do have gills. In fact, they're on each side right under the main part of the shell (thorasic carapace - main area in front of the tail). The reason crayfish can live for awhile out of water is that they're able to carry a bit of water within their shell around the gills. So, in effect, they have kind of a reserve. As long as they have some water, their gills can obtain oxygen for the body. As this dries out, the crayfish must return to water or it will die.
If you look on the underside of the tail, you'll see small, paired extensions called swimmerets. In females, they're all about the same but in males, the first pair (those closest to the body) are enlarged and fold up toward the head. The male's specialized swimmerets allow the male to fertilize the female. Males also have larger claws than females but this is difficult to use for sexing since these vary quite a bit. Hope this helps.
John Wiessinger ( April 3, 2006)