Monday, October 12, 2009

Vegetarian Spiders!

In another tribute to science journalism by press release, I've seen three articles on this news so far today, (BBC, NYT, NatGeo) with none of them addressing the question that most intrigues me: How do the spiders eat these vegetables? Spiders normally kill or immobilize their prey with venom, then follow that up with an injection of digestive enzymes and other substances that liquifies the flesh within the keratinous skeleton (or skin, if it's not an arthropod). Then they suck out the digested soup.

The acacia-ant commensal pairing is a classic example of two different organisms evolving a relationship that benefits both; the acacia has little protein-rich bodies hanging off the tips of young leaves called Beltian bodies. The ants are very happy to have a ready source of protein, and aggressively defend their home tree from other organisms. Some acacias have even evolved hollow spines in which the ants reside. So the trees get protection, and the ants get room and board.

The spider has learned to avoid the ants and eat the Beltian bodies. It spends most of its time in parts of the tree with no food, where the ants don't spend much time, but when it gets hungry, it darts in, jumps and dodges the ants, and goes veggie shopping. The BBC and NYT articles have vidclips showing examples of this expeditionary herbivory.
As I said to Lydia when I sent her the link to the first article, "Yet another long-established "fact" gets pwned."

1 comment:

libhom said...

I wonder if these spiders thank the meat eating spiders are immoral.