Lecture 16-Rotifers.pdf - Classes at U. of L.

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Single ovary with one egg A rotifer carrying a single egg attached to its body Lorica—shield-like ‘shell’ sometimes with spines Class Monogononta—”single ovary” •Benthic, free swimming, or sessile forms, •lorica present or absent, •foot present or absent-toes variable, •corona usually a single ciliated disk ringing the anterior end, •mastax not ramate ‣1600 species, mostly dioecious alternating between parthenogenesis and sex ‣Males are usually small, with a vestigial gut, and only for sex
The Monogonont life cycle Usually while food and survival conditions are quite good most of the population are females which produce diploid eggs that hatch to make identical copies of the female parent. During autumn the stimulus to undergo meiosis, and make haploid (mictic) eggs occurs, then if those eggs don’t get fertilized they hatch out as males. Males will then seek out mictic females and have sex with them. The eggs produced are larger and contain more nutritional reserves than normal parthenogenetic eggs, and delay hatching often till the following spring or when suitable conditions occur. Some females can do both-Amphoteric Pseudosexual eggs—parthenogenetic eggs that look like resting eggs have been noted in some species.
Page 1 and 2: Phylum Rotifera—”wheel bearers
Page 3 and 4: Close-up of the jaws-trophi of a ro
Page 5: Closeup of the ramate mastax of Phi
Page 9 and 10: Lorica with anterior and posterior
Page 11 and 12: lorica with 3 very long anterior pr
Page 13 and 14: What conditions are good for rotife
Page 15 and 16: The incudate trophi of Asplanchna p

Lecture 16-Rotifers.pdf - Classes at U. of L.

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