So polychaetes are funny looking eh?

When I was a lowly museum technician working on the Antarctic invertebrate collections, I remember the funny fat worms with copper-colored bristles. This was my first introduction to polychaetes, aka bristleworms:

Meet Hermadion magalhaensi, an Antarctic representative. I don't know if we are looking at the bottom or top...

Poly + chaetae = many bristles, they always reminded me of those bristly brushes one would use on horses or someone with really fine thick hair. That would be one expensive brush because these critters live mainly in the deep ocean and you would need a lot to make a full brush. Polychaeta is a Class within the larger Phylum Annelida (segmented worms; not to be confused with non-segmented worms, the Nematoda, which include your intestinal parasites!*). Anyways, they are a pretty adaptable group of critters, some live in the uber-hot, chaotic cities of hydrothermal vents, others settle on the cold cold lonely abyssal plains. Some live in self-secreted tubes! Some are free-living! Some are parasitic! You get the picture, very diverse. The ones most people will be familiar with are the christmas tree worms:

"Cuz dey purdy!"

But if you look at one real close up it is a completely different animal:

This one looks like a hungry baby.

This one looks worried. Are those sensors of some sort? The picture is more amusing if I pretend they are eyes. Unfortunately, you don't get much in the way of actual information in this online gallery, still amazing SEM images.

Animal mouths are so weird. The incisor-like teeth and puffy cheeks of the former image actually made me flashback to a critter we had our students learn in Vertebrate Biology lab: pocket gophers!

Family Geoymidae. Look at those claws!

In the Order Rodentia, blah blah blah...burrowing, yup yup....ruining vegetable gardens.....external cheek pouches....Excuse me, what was that last one?? I had to do a double back when I came across this curious aspect of their anatomy. Turns out the 'pocket' in pocket gopher refers to cheek pouches they stuff food in on the outside of their mouths! Being so, they are lined with fur!

Nota bene: see how the lips close behind the front incisors as to not let dirt get into their mouths whilst digging.

I saw an old paper laying out how this might have happened: a particularly deep-dimpled ancestor gopher might have had a nice life because it was able to haul more food. It's babies also had this trait which was carried down through more descendants becoming augmented to the pouches we see today. Evolution leads to some weird forms doesn't it? While grading final exams earlier this month one student had a good zinger that went kind of like this: "Evolution is acting upon all of us, and frankly, I don't think it has any idea what it's doing."
So true :)


* Have you ever looked up how many animal phyla there are? A number like 14 or 20 sounds reasonable right? WRONG! There are currently 35!