Strongylocentrotus Purpuratus

The Purple Sea Urchin!!

This lab was pretty fun, I have always wondered what is going on underneath all those spines!

The aboral side, this is how they look when you see them in the ocean. Their anus is right in the center there.

 

This is a view of the underside. That is the mouth right in the middle. They have 5 teeth.

A close up of their spines and tube feet. You can see how the tube feet have lines down the middle. Water enters the foot high in waste and low in oxygen and leaves the foot to reenter the body high in oxygen and low in waste,

Couldn't get a good picture of this, but those little white dots in the center are called pedicellariae. They are three sided pincher like structures sitting on stalks. They would open and close and grab around and looked like hungry little baby dinosaur mouths. These guys prevent anything from settling in or growing on the urchin. 

If you want to see them in action, watch the video below and look at the tiny stalks in the center. You can see them grabbing around, it's really cool.

The first view into my urchin after I cut out a window (which was not easy to do!) That big orange thing is the gonad or gamete producer. They have 5 gonads.

I quickly found out my urchin was a male. It was spewing  sperm which can be seen in the picture above. This led me to change my water every ten minutes... Not fun.

One gonad removed, here is what the insides looked like.

A view after I cut along the equator and the whole aboral side was removed

A view after all reproductive and digestive organs were removed

A close up of Aristotle's Lantern

This was the last lab of the quarter! I'm excited not to spend four hours drawing things but also sad because it was really interesting and fun to share. Lab practical is next week, wish me luck!