Thursday, June 3, 2010

An Instance of Symbiosis

Some hermit crab species pluck young anemones from the sea floor and place them on their own bellies; the anemones attach, and find themselves fed with scraps from the crab's feeding. The crab, on the other hand, receives a protective shell in the form of the anemone's large fleshy foot, which grows up and over the hermit crab's otherwise-unprotected back.

Above, a scan of a sketch of this interaction, with the anemone's tentacles visible at the crab's belly, and the anemone's foot growing up and over the crab's back. This is a print-size reproduction of a sketch I've made of this instance of symbiosis (as it will appear in The Fact of Evolution); I have to be careful to draw on a scale and in such a way that small line art of this kind reproduces well. The text is not as it will appear; just notes to myself for the moment.


Laura said...

still one of my favorite things about the evolution "debate" is that every perfectly illustrated example you can give about how evolution works, someone will flat out deny it and argue that just an example of the opposite:

I found this while trying to find pics of the crabs with anemones on them. Good for an eye roll anyway!

Someone gave me a DVD one time that 'proved' that fireflies could not have evolved because the chemicals in their rears would cause explosions if not mixed properly. An interesting theory if you can discount the logic that bugs who've exploded don't generally do too well in the reproduction category..

Either way, ever since then, I've enjoyed a great visual of a Gary Larson type god with an eyedropper, singed off eyebrows, and the smoking remnants of a failed firefly creation mumbling something like, "Whoops.."

Do you know if the foot of the anemone grows and expands with the crab as it grows? Or at some point in time does the "anemone shell" interfere with the crabs growth?

Cameron McPherson Smith said...

Hi, Laura, I mean to answer -- but I have to get to field school right now :)