An interesting look at the spiney-skinned sorts. http://www.youtube.com/user/PieWieDutchRebel#p/u/42/zlc3RR6B66U
Click on the link to see the fertilization of a sand dollar egg and the first stages of development. http://www.youtube.com/watch?v=w_ydqBzVe9g
Click on the link to learn the basics about sea stars and watch one eat from the viewpoint of a mussel. It’s the attack of the killer cardiac stomach! http://www.youtube.com/watch?v=6Z0K4RKwa5E
Click on the link to see a BBC clip on the urchin barrens of the Pacific Northeast. http://www.youtube.com/watch?v=HG17TsgV_qI
How the sea urchin got it’s guts. https://www.youtube.com/watch?v=AD4t5ijilYM