Question

1) Observe rotifers feeding on red-stained yeast particles. Does rotifer behaviour change when food is encountered?

2) How are food particles handled? Briefly describe the method rotifers use to search for and capture prey items /1 (Research and cite sources if not directly observed

3) Hydra has been described as “non-senescent”. Explain? cite sources)

4) Explain the mechanism and role that diapause plays in the life cycle of Artemia

5)Explain how a filter feeding lifestyle contributes to phenomena such as Paralytic Shellfish Poisoning (PSP)

Answer 1

3) Unlike the other metazoans, Hydra does not experience senescence. As per the hypotheses, proposed by NCBI, the Hydra controls damage accumulationmainly thorugh damage dependent cell selection and cell sloughing. They have examined their hypotheses,with a model that combines cellular damage with stem cell renewal, differentiation, and elimination. The hydra stem cells are a large pool of three types of stem cells with some features of differentiated cells. This large stem cell community prevents, "cellular damage drift" which is inevitable in other metazoans. Theri results suggests that non-senescence is possible only in simple hydra like organisms hwhich have high proportions and number of stem cells, continuous cell division, an effective cell selection mechanism, and stem cells witth the ability to undertake some roles of undifferentiated cells.