This pouch is located ventral to the thorax and is formed of large, thin setose plated attached to some of the thoracic appendages. The plated are on the medial aspect of the appendages and project medially to form, collectively, a basket into which the eggs are released and in which the young are brooded. The only peracarids orders in southeastern fresh waters are the Isopoda and Amphipda. Within the confines of the region and the freshwater habitat the two are easily distinguished. Isopods are dorsoventrally flattened and amphipods are laterally compressed, or flattened from side to side.
Amphipods are usually much more active and agile than the slow moving, crawling isopods.
Both orders are characterized by possession of 7 pairs of leglike thoracic appendages and the number of legs in not a good character for separating them. Identification of amphipods to species often requires dissection but that is beyond the scope of this course. You can find the structures described in this exercise by simple manipulation of the specimen with minuten teasing needle and fine forceps. At the supply desk find a vial containing either a non-reproductive amphipod of either sex. Do not use the vials with green caps.