29 August 2007

Gastropods and isopods

My background interest in terrestrial isopods (Oniscoidea) suddenly flared up a few of weeks ago. I did some searches on the Internet, downloaded a bunch of papers and ordered from Amazon a cheap "like new" copy of S.L. Sutton's Woodlice (yep, that's what they call'em over there across the Atlantic). Sutton's 140-page book, first published in 1972 and which I finished reading today is an elementary introduction to isopods. I would consider it a technical book, because it is for readers with a background in biology, but it is not too detailed. Now I can move on to more technical stuff.


As I was finishing Sutton's book, I started thinking that gastropods and isopods have several things in common, besides being the co-subjects of this post.

1. Both groups have terrestrial and marine representatives unlike, for example, insects, which are almost entirely terrestrial (except for the freshwater larvae of some groups and some coastal species). And because both groups evolved from marine ancestors, there are terrestrial species of snails and isopods that can survive only in habitats near the sea.

2. Both groups use calcium carbonate to build exoskeletons.

3. Both groups are more likely to be found in high-humidity habitats and in places that offer hiding places from the environmental extremes. Nevertheless, specialized species of gastropods and isopods can be found even in certain deserts.

4. The names of both groups end with the suffix pod; a gastropod is a "stomach-foot", while an isopod is an "equal-foot".

5. According to Sutton, isopods like to eat paper: "A liking for paper extends to any data labels put into a culture-they don't last long!" So do land snails. Don't ever put papers with location information on them in the same containers with live snails!

Future posts about isopods are in the works.


Coyote said...

"Both groups use calcium carbonate to build exoskeletons."

Hmm, that explains why I saw a pillbug sitting on the piece of cuttlefish in my H. aspersa's terrarium today.

Anonymous said...

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Kevin Z said...

Since when do isopods have calcium carbonate exoskeletons?? I thought it was chitin...


It was news to me too. Apparently it is chitin reinforced with calcium carbonate.

Kevin Z said...

Is this only for terrestrial isopods? The marine oe i've seen and studied certainly don't seem to have any CaCO3 in their exoskeleton.

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