Today in our lab we looked at the big picture (dissections of molluscs and echinoderms) and the small picture (histology slides of diseased and healthy oysters and abalone). The big picture allowed us to familiarize ourselves with the various body parts of these animals and also to discover just how hard it is to cut through a pisaster ochracheus. The small picture introduced us to the difficulties and sometimes joys of differentiating tissue types and identifying parasites.
Here is our dissection of a diseased pisaster ochraceus:
You can see the Anus in the middle surrounded by the stomach, the radial canals/nerves extending down the arms, the yellowish gonads and greenish cecae or digestive glands, and the ampulae (white sacks on each arm) which control the tube feet.
Next, we have a picture of a sectioned and stained abalone infected with Coccidia:
Coccidiae are obligate intracellular parasites, which infect the kidneys of abalone.