Aplacophorans: The fuzzy little Mollusk you don’t know

mollusc copybiogallery-ImageF.00062Cute and cuddly may not be the first words you would to describe a Mollusk. A group whose name literally means “soft-bodied” in Latin. However, the approximately 300 species of aplacophorans are quite cute. These cylindrical mollusks lack the shells of their brethren but rather are covered in small calcified spicules that given them a fuzzy appearance.   Most of these cute little buggers are no longer than couple of inches but some can top out at a full foot in length.

aplacophora_smCompared to other mollusks aplacophorans are quite simple and different. So different that at one time they were thought to be sea cucumbers. Not until1987 were the officially classified a mollusk.   The head of aplacophorans is pretty simple and lack eyes and tentacles. The have single opening, called a cloaca, in which the excretory and reproductive systems both empty. One hole to rule them all if you will.

Most of the species live either crawling around in or on top of the seafloor sediment.  Depending on the group of aplacophorans, these little guys are either fierce hunters of cnidarians, or in contrast, grazerspicking bits of good out of the sediment.

The simplicity suggests the aplacophorans are the ancestors to all other mollusks. However, a fossil found in 2012, Kulindroplax, tosses this idea aside. This fossil aplacophoran contained plates like chitons, another group of mollusks. This suggests aplacophorans evolved from a shelled ancestor as opposed to all other mollusks originating from an ancestor without shells.

Well the great granddaddy of mollusks or not you cannot deny their cuddliness.  Although this pink one does look a bit like a fuzzy penis.

One Reply to “Aplacophorans: The fuzzy little Mollusk you don’t know”

  1. They all look like penises LOL but in that regard, their resemblance is only vague compared to the penis worms. They are all put to shame by Atretochoana eiselti. a caecilian. I’m sure you know what it is, but if you don’t an image search should make it clear that when it comes to penis mimics it’s the champ.

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