CIVILIAN PERMANENT CHANGE OF STATION (PCS) CHECKLIST. A PCS move involves a great deal of advance planning and hard work. We would like to make this transition as. smooth as possible by providing this guide. Remember that this guide is just that-a guide, and does not supersede. any laws, regulations or directives that are already in place. 6 months out Report date -180 days.
Thus it is clear that cloaca is used for excretion as well as reproduction. This is also the opening that is used for laying eggs. Anus on the other hand is simply an opening at the distal end of the alimentary canal. It is a passage for undigested waste only.
Gills. The purpose of a fish's gills are to enable it to obtain oxygen from the water. A fish's gills contain special membranes that absorb oxygen and also release carbon dioxide. Basically a fish's gills has the same function as a person's lungs-the gills are where gas exchange occurs. Water has oxygen dissolved in it, which the fish needs to survive. The fish takes water in through its mouth and this water passes over the gills. The gills contain lots of blood vessels.