BIO 2135 Lecture Notes - Lecture 10: Coelom, Peristomium, Annelid
7 Feb 2017
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Document Summary
Trochophore has prostorem, peristomium, pygidium all evolved into different parts of annelida. Everything in between these parts are metamerized. Some take on caterpillar like appearances, bristles used as defensive structures. Some are tubes, bury in the ground, line the tube with chitin. Leeches are terrestrial annelids that have adapted to the aquatic environment. They have an epithelial layer (gas exchange surface) - must keep it moist if a terrestrial organism. Circular (setae in) and longitudinal (setae out) muscles. Dorsal, lateral, and ventral vessel run different ways. 5 aortic arches ( heart ) blood goes from dorsal to ventral. Esophagus: basically a conduit, to get the food to the next part of the digestive system. Crop: where you store food prior to digesting. Calciferous glands sequester calcium so there is not too much. Every segment has a pair of metanephridia. Everything is metamerically arranged, except for the gut. When something swims by, it shoots out its pharynx and eats it.
