Re: My crayfish has worms attatched all over her body.

Dear Tessa,

Those worms on your crayfish are called branchiobdellidans. They are 
distant relatives of earthworms and leeches. Branchiobdellidans live 
almost exclusively on crayfishes. Most of them probably feed on the even 
smaller organisms that are also present on the crayfishes. They are not 
likely to cause much harm to Lucy. Would you consider leaving them on her? 
That way, you will have more things to study! If you have a microscope, 
you may want to look at some of the bigger worms under the microscope. You 
should see a mouth at one end of the body and a sucker at the other end. 
The worms use their suckers to attach themselves to the crayfish. 
Sometimes more than one species of branchiobdellidans may be found on a 
single crayfish. You may be able to tell some species apart by the 
different shapes of their bodies. If you place the crayfish in a shallow 
container of water that will fit under a dissecting microscope, you may 
see through the microscope what the branchiobdellidans are eating.

But if you really want to get rid of them you may have to pick them off 
one by one with tweezers. The branchiobdellidans that are more likely to 
harm a crayfish probably live on its gills and other soft tissues. But a 
crayfish would give you a pretty hard time if you tried to examine, let 
alone touch, its soft parts.

If you need more detailed information on branchiobdellidans (and 
crayfishes), try the following book.

Thorp, J. H. & A. P. Covich (eds.) Ecology & Classification of North 
American Freshwater Invertebrates. Academic Press (1991).

There is also some information about branchiobdellidans at this Web site:  
http://www.pac.dfo-
mpo.gc.ca/sci/sealane/aquac/pages/branapcy.htm


Enjoy your Summer.

Aydin Orstan