Week 4

The fourth week came without my normal abnormal occurrences, which saddened me greatly. The Rotifers were “inch worming” around. There were, however more of the smaller rotifers and less larger rotifers. The smaller the size of the Rotifer is the less color it seems to have and the more it seems to antagonize the larger ones. I witnessed the one with the “horn” again. It was holding on to the glass, the cilli were going around, and it was contracting in and out. Another person in the class with me has seen this on their Rotifers, too, which makes me begin to think that maybe all Rotifers have the “horn” or maybe it is a different species. I also saw some spots that looked like rolled up rotifers. I think that maybe this is some rotifer eggs.

The majority of the Rotifers were concentrated near the food, which has almost disintegrated. The water in the MicroAquarium has become cloudy and is containing much more algae. I believe this is due to the food disintegrating.

The debris at the bottom of the aquarium has strands growing out of it and the moss seems to be growing towards the top (where the light is).

As I furthered my research this week I discovered many interesting new facts about the Rotifers. The rotifera has a more highly organized internal organs system than the most advanced protozoan. Most of the Rotifers have stomachs, in a previous week I was lucky enough to get to see one work. They have extensive diets. Most of the rotifers are filter-feeders. They eat bacteria, protests, suspended organic matter and even other rotifers. The filter-feeders are able to eat particles up to about the size of a small alga. The filter feeders can filter up to 1000 times their own body volume each hour. Sadly enough there is a large group of herbivores that eat these fascinating creatures.

The life cycle of the rotifer is generally parthenogentic. This means the egg develops with fertilization into a new individual identical to the mother. The fertilized eggs are developed into thick-walled resting areas. Species that are not entirely parthenogentic produce males only during a short period at a specific time during the year. The male rotifers may not be collected if samples are not taken frequently enough.


~Rescources~

Rainis, Kenneth G., and Bruce J. Russell. Guide to Mircolife. Danbury: Franklin Watts, 1996.

Garnett, W.J.. Freshwater Microscopy. London: Constable and Company Ltd., 1953.

Bronmark, Christer, and Lars-Anders Hanson. Biology of Lakes and Ponds. New York: Oxford University Press, 1998.