09 June 2008

Arboreal isopods

Tree climbing isopods were featured on this blog before in this post.

Last Saturday night after a thunderstorm, I found 2 species of isopods on the trunk of a young apple tree in the backyard. One of them was Philoscia muscorum*.


And the other one was Armadillidium nasatum. Here are representatives of both species together after I brought them indoors for a closer look. Philoscia is on the left, Armadillidium is on the right.


Why do isopods climb trees? Probably they feed on the fungi that grow on tree trunks.

*My isopod identifications are always tentative, pending confirmation. So I could be wrong.


Mike O'Risal said...

Isopods may also climb trees because of a nematode parasite that affects their behavior. They need to keep their gills wet so they generally stay in dark, moist places and avoid sunlight. However, the parasite needs to enter an avian host to complete its life cycle. It will cause the isopod to abandon normal behavior and make itself a target.

Generally speaking, there's plenty of fungi to eat in the places where isopods live without them needing to climb trees.


But this was happening at night when there were no birds around.

They may be going after the cyanobacteria actually, which can't grow in dark places.

Mike O'Risal said...

Oh... I missed the part about it being night time.

I suppose it might be. Or maybe these were just extreme isopods.