Salinity Changes on the polychaete, Nereis succinea

I 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 tank of water of foreign salinity, or whether they would simply continue 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 9:30am to 10:30am. 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 four 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

ter the worm to dilute it, to make the solute concentration less dense. When the concentration of solute is the same in the worm and in the water, no more water will enter, and equilibrium will have been reached. In this case, equilibrium was never reached. The salinity was so low that water kept entering the worms, and the worms got bigger and bigger, until they popped, because their epidermis could not expand any further.

salmon color to them, and on two opposite sides, they have these crimson hairs lined 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 west", 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 pulse that is supposed to conspicuously travel up and down this vessel, we were not able to l!

she returned at 4:00pm to weigh them once more. By this time, of the ten parts per thousand worms, Goliath continued growing (he was a whopping 8.2 grams), Louie had leveled off at 3.4 grams, and Pedro was dead. All the 32 parts per thousand worms had basically leveled off.

I then came in on Monday, May 12, 1997, and weighed them at 10:35am. Over the weekend, the last remaining low salinity worm, Louie, looked as if he was dead too. He was all bloody, and the water in his bowl was murky, so I figured he was dead, but then I saw him moving. He was in bad shape but still alive. So I weighed him, and he had decreased 1.1 grams. Of the high salinity worms, Boris was dead, and Jenny and Dopey had continued to decrease in volume (Jenny: -0.3 and Dopey: -0.6). Then I put all the worms that were still alive back in the control tank. I then threw away the dead worms and rinsed out all the bowls. We were planning on repeating the experiment on Tuesday, May 13, 1997, but most of the worms were dead when we got there.

Some topics in this essay:
Jenny Dopey, Patty Jeremy, Boris Jenny, Salinity Changes, Louie Pedro, salinity worms, low salinity, equilibrium reached, thousand worms, reached equilibrium, 24 thousand, ten thousand, control tank, jenny dopey, nereis succinea, decreased 11 grams, looked reached equilibrium, entire length bodies, 32 thousand worms, decreased one-tenth gram,