Anywho, we're working with two different species - dendraster excentricus (a sand dollar) and strongylocentrotus purpuratus (a purple sea urchin). We were originally only going to use the sand dollars, because their eggs are so much prettier.
This is a sand dollar egg - notice the pigment cells around the egg in the jelly layer.
And these are the urchin eggs - no pretty dots around, so Dr. B likes them less.
To get the animals to broadcast their gametes, we inject them with KCl. This gets them CRAZY excited. Ever think that an urchin might not be an animal? Check out this clip - watch that sucker dance!
So, I uploaded a picture of each early development stage of both species, but now that I think about it, I doubt y'all are that interested. So I'll just share a few of my favorites.
4-celled sea urchin. See that circle surrounding it? That membrane forms after fertilization
One reason why we're working with both species is because only two of the groups were able to get their sand dollars to take. My group was one of them, but in the process, many of our cells lost their jelly coats when they were exposed to too much heat. Which is lame, because aside from that, the two species have more or less identical embryos. It means I have to be RIDICULOUSLY meticulous about labeling the pictures and paying attention to when I took samples of which..... blech. Also, while changing out their water, we got a bunch of filter paper in with the eggs, so a lot of our pictures have fibrous nonsense in the way.
BUT, things are a lot less stressful now that things have at least started moving. We spent the first three hours or so of today fretting over these sand dollar eggs that just would not take. Now that things are moving, we can sit back, relax, and watch these babies grow! Tonight my shift is from 10-1 a.m. - not too much later than I'd already be up. I'm not excited for the 1-4 shift, though....
This is seriously so awesome! How does this project work? I want more details! I'm very interested. And I definitely don't think seeing more pictures would be boring.
ReplyDeleteWe inject them with the KCl, which makes them broadcast their gametes - this filmy layer of sperm/eggs shows up on top of them, and would go floating out in the water if they were in the water.... but they aren't.
ReplyDeleteSo, we turn them upside down in these beakers and let the gametes mix. We have to filter the water out every few hours or so to try and keep it clean of bacteria. We also keep all the beakers in a tub with water continuously flowing into it, so that they stay cool. Once they get to a certain stage (which my group's never did), you add some food so that they'll continue to grow.
Other than that, you just put some drops of the solution onto a slide every now and again and check it out!