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Effect of Temperature on the Heartbeat of Daphnia
Daphnia, the water flea, is a crustacean commonly found in fresh water. It is an important herbivore and feeds on algae and is in turn a common food item for many higher trophic levels including fish. Thus, this organism is an important link in the aquatic food chain. Daphnia is small and transparent, making its internal anatomy easy to view. As a result, one can study a number of environmental effects upon the action of the heartbeat of Daphnia. It is also a useful organism for studying the effects of drugs on the heart.
Click to view an image of Daphnia
Consider the following questions:
This group includes such well known organisms as the spiders, ticks, mites and scorpions. Adults are characterized by having four pairs of walking legs.
Most Manitobans are familiar with wood ticks. The common wood tick, Dermacentor variabilis, is often extremely abundant in some areas of the province in late May, June, and July. You should recall from the lab that ticks exhibit sexual dimorphism with the female having a scutum covering only the anterior, dorsal surface, while in the male the scutum covers the entire dorsal surface. In the female, it is the portion posterior to the scutum which expands when engorged with blood. The capitulum (head) includes a complex set of mouth parts for attachment and feeding.
Ticks are of considerable economic importance because they transmit diseases such as tick paralysis, rocky mountain spotted fever and tularemia. They may also cause problems due to infections and in the case of animals, anemia due to blood loss. Despite these problems, ticks in Manitoba do not present a serious hazard in humans.
Examine the preserved tarantula from your lab.
Arachnida