Wednesday, March 30, 2011

Six Legs vs. No Legs

Worms, more specifically earthworms. Those long slimy segmented squirmy organisms that live in the dirt. At first glance the may possibly seem like the most simple organism there could be. So, there is no possible way their could be a single similarity in earthworms with grasshoppers. Right?

Earthworms are a part of the Annelid phylum. Annelid came from the french word anneles which translates to "ringed ones", due to earthworms segmentation. You would believe the anatomy of an earthworm to be fairly simple; howe
ver, they were the first to show evidence of a complete digestive system. Of course its not extremely complex, still pretty impressive for such a simple looking organism. Basically the worm is made up of a through system starting with the mouth, crop, gizzard, intestinal tract and ending with the anus. The segmentations on the worms outer surface internally designate a closed area of organs, such as the nephridia. The nephridia works like waste management, excreting it from the body (nephdria). Typically the worm will have two of these bad boys, to keep things under control.
The worm has quite a bit of other unique anatomical characteristics about it, such that it has a vascular system, it breaths through its skin, and they are typically hermaphrodites so they reproduce asexually!

BUT, what I am getting at is what the heck do they have in common with a grasshopper? Grasshoppers are in the phylum Anthropoda. Anthropods have segments similar to the earthworms; however, each segment posses a set of appendages. Grasshoppers have an open circulatory system unlike the worm. They have three primary regions of their body, the head, thorax and the abdomen. Located in the thorax are malpighian tubules, which has a waste management type of function (MT). Sound familiar? THATS RIGHT, worms have something like this too, the nephridia.

There are so many differences in between these two organism, it is neat to see something that is conserved in both of their internal anatomy. It is even more interesting to think that we have a vary similar organ, our kidneys, that possesses a similar function as the nephridia and the malpighian tubules. It all goes back to evolution. Both the annelids and the anthropoda are both protosomes, a clade of invertebrate animals, making sense as why they would have some similarities in their anatomical make up.

1 comment:

  1. This was really interesting! And I, too, would think that earthworms would be the simplest organisms to study.