Rotifers are multicelled animals. Because they are so small most people have never heard of their existence. They are about the same size as the larger unicellular organisms. They don't have a lot of cells, less than 1000, but they have some very special attributes. They are wonders of miniature design.
At the front of the body they possess a crown of hair-like cilia. They locomote by using the crown of cilia (the corona) to propel themselves. Some species walk with head and foot. Their foot (also called spurs) can secrete a sticky substance that enables them to attach to a surface.
They also use the crown of cilia to wave food into their mouth. There the food is passed into the mastax'where it is ground up and then directed towards the gut. You can often see the mastax moving as it begins the digestion process. Rotifers are so transparent that all these organs can be observed easily. They have one or two light sensitive red eye spots.
Because many species make so-called resting spores which are easily carried by the wind, they can be found anywhere if there is a little bit of water. Even in a roof gutter or in birdbaths.
Observe the Rotifer-- Use the scanning lens to find a rotifer, they are usually easy to spot attached to algae. Some may be seen swimming across your viewing field. Switch to the LOW power objective.
1. How does the rotifer
attach itself to algae? ___________________________________
2. What is the function of the mastax? _____________________________________________
3. Describe how the mastax and cilia moves. What is the function of the cilia near the opening of the mouth? ________________________________________________________
4. Sketch your rotifer. LABEL (either on your drawing or the drawing above) the mastax , spurs, mouth, and gut.
-- When you get your slide, smell the drop of water on it. This should give you a clue as to how these nematodes got their name. Nematodes that are commonly referred to as "vinegar eels" (Turbatrix aceti) exist by feeding on bacteria and fungi found in the sediments of nonpasteurized vinegar. When viewed alive, vinegar eels are seen to be in constant motion.
5. Where do vinegar eels live? _____________________________________
6. How many nematodes do you think are on your slide? ______________________
7. Sketch the shape of the nematode. Is there an obvious anterior side (or head)? ______
Trichinellosis, also called trichinosis, is caused by eating raw or undercooked meat of animals infected with the larvae of a species of worm called Trichinella. Infection occurs commonly in certain wild carnivorous (meat-eating) animals but may also occur in domestic pigs. Trichinella worms belong to the Kingdom Animalia and the Phylum Nematoda.
When a human or animal eats meat that contains infective Trichinella cysts, the acid in the stomach dissolves the hard covering of the cyst and releases the worms which mature and eventually make their way back to the muscles, the worms curl into a ball and encyst (become enclosed in a capsule).
Obtain a slide of muscle tissue infected with trichina cysts. View the slide under scanning and low power. Look for long striped muscles with circular cysts embedded within.
8. Sketch the muscle tissue and use an arrow to indicate where the trichina cysts are located.
9. Sketch your worm
10. Pictured is a diagram of the liver fluke. Two intermediate hosts (vectors) are shown; what are they?
11. To what phylum
does the tapeworm belong? ______________________
12. Sketch the tapeworm. Label the proglottids, the scolex, and the hooks.