salinity

A detailed Summary of salinity

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 salmon color to them, and on two opposite si

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.

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 !

ocate 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.

I made another very shocking and interesting discovery the first time I took a worm out to weigh it. I took it out with a net and put it on a paper towel, and as I was walking to the scale, this "thing" jumped out at me from inside the worm (I literally almost dropped the poor guy!). The only way I can really explain it is if you take a sock and turn it inside-out. The worm basically extended its body by "unfolding" this unknown thing from inside. After the initial scare, I later come to realize that this is called the "reversible probascis" or something to that effect. I learned that the worm uses it to catch small fish when it is hiding in some seaweed. I also observed it later and found little teeth on the end of the probascis. That basically sums up the activity that I noticed.

After observing the worms, I formulated the hypothesis that, when facing a change in salinity, the worms would adapt osmotically to the environment and their volumes would change, but they would not make any efforts to re-adapt back to their original volumes. The reasons I formulated this hypothesis were quite frankly less than scientifically stable. When I looked at the worms, I saw a very basic physiology, and I suppose I figured that a basic physiology like that would be less capable of engaging in re-adaptive processes. I know that this hypothesis was based on a whim, but that is honestly how I

Some common words found in the essay are:
Jenny Dopey, Patty Jeremy, Boris Jenny, , Louie Pedro, salinity worms, equilibrium reached, low salinity, reached equilibrium, thousand worms, control tank, ten thousand, jenny dopey, change salinity, 24 thousand, decreased 11 grams, 32 thousand worms, looked reached equilibrium, decreased one-tenth gram, entire length bodies,

Approximate Word count = 1969
Approximate Pages = 8 (250 words per page double spaced)

Category: Science