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

As for the higher salinity worms, they basically acted how I suspected them to act. Their volumes continued decreasing. Both Boris and Jenny did have one measurement in which their weights actually increased, and I honestly do not know how to explain that. They all looked at one point as if they reached equilibrium (especially Dopey), but none of them did.

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.

I very much enjoyed this project, and I truly, honestly did learn a lot from it (and I'm not just saying that). If I were to do it again, I would not have made the change in salinity so great. It would have been interesting to see what would have taken place if the change in salinity were only, say, six parts per thousand higher and six parts per thousand lower. Maybe next time we'll do that.

The opposite is true of the worms placed in higher salinity. The concentration of solute in their bodies was less than that of the water, so it expelled water to make its own concentration more dense. Again, this happens until equilibrium is reached, and in this experiment, it appeared for a moment as if that occurred, but the worms either died or continued decreasing in volume.

We began the experiment on Thursday, May 8, 1997. We came in at 7:30am to mix the salts and set everything up. The control tank was at 24 parts per thousand. We decided to put three worms (named Goliath, Louie, and Pedro) in 32 parts per thousand and three worms (named Boris, Jenny, and Dopey) in ten parts per thousand. We started weighing at 8:10am. I picked them up with my bare hands (what a stud I am!), Jeremy dried them off with a paper towel and put them in the container on the scale, and Patty recorded the time and weight. We also made sure to dry off the container after every use to make sure that the excess water did not get calculated with the worm's weight. We weighed all the worms every half hour until approximately 10:45am, when Jeremy and I had to leave. Patty stayed and continued to weigh the worms, but only every hour rather than half hour, because the rate of their changing had begun to slow down. She stayed and weighed the last worm at 1:45pm. Then !

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 sout

Some common words found in the essay are:
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Approximate Pages = 8 (250 words per page double spaced)