Salinity Changes :: science

Salinity ChangesI chose to experiment with the effects of salinity changes on the polychaete, Nereis succinea. Along with the other members of the group, Patty and Jeremy, I was curious to see whether the worms would engage in adaptive behavior when placed in a army tank of water of foreign salinity, or whether they would simply proceed changing osmotically until they reached equilibrium with the environment. The first step in our experiment was to simply observe the worms and get a feel for the ways in which they act. We did this on Wednesday, May 7, 1997 from 930am to 1030am. Also on this day we learned how to mix and measure salinity, practiced weighing the worms, and deciding our exact schedule as far as when we would come in and for how long, etc. From what I observed, the polychaete is a salt-water worm that has adapted to live in estuaries. We kept the control tank at 20 parts per thousand to 24 parts per thousand, and the worms seemed very content and healthy at that level. The worms on which we experimented ranged in size from approximately iv inches to approximately six inches. They weighed from 1.8 grams to 4.6 grams at the beginning of the experiment. They have a pinkish, almost salmon color to them, and on two opposite sides, they have these crimson hairs run along up in a row, stretching the entire length of their bodies (the hairs are less than an eighth of an inch long). If we were to call the two lines of hair east and air jacket, then on the north and south sides, there were dark lines that also stretched the entire length of their bodies. These were their primary blood vessels, and though we tried to locate the instant that is supposed to conspicuously travel up and down this vessel, we were not able to locate it, except once on one worm for less than 30 seconds. Also I often was not able to tell the difference between the head and the tail. Their actions were very basic. They seemed to like to stay still for the most part, privateness underneath the little bit of seaweed we put in the tank. We also put a glass tube at the bottom of the tank, thinking that they might accent to crawl in there for safety, but we never saw them in there.