More about amoeba teeth

A couple of blog posts ago, I discussed some recent research suggesting that some testate amoebae use their shells for predation. Yesterday, I was looking at samples from Mer Bleue Bog, and came across some more specimens of the handsome amoeba I mentioned in that post, Netzelia corona. I took some time to look more closely at these pretty shells.

The ones in this population are quite “tubercular”, covered with spherical bulges that make them look a bit like blackberries. The aperture, as always, is beautifully made, featuring a wavy lip composed of organic cement mixed with mineral grains.

If you look closely at that lip, you can see how carefully the amoeba has chosen and placed its building materials. Each lobe is made up of an aggregate of uniformly sized minerals suspended in organic mortar. At the tip of each “tooth”, Netzelia has selected sharply pointed particles and positioned these so that their tips point inward.

The same arrangement is repeated all around the inner surface of the aperture:

I try to avoid speculating about the purpose of morphological structures, in case the ghost of Stephen Jay Gould decides to haunt me for telling evolutionary “Just So stories”. Still, the sharp points on these teeth would be pretty handy for shredding prey organisms, wouldn’t they?