The Effects of Caffeine on Daphnia

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This experiment is to see The Affect of Caffeine on Daphnia. Daphnia is also known as a water flea. It is a distant relative of crabs and shrimps. (Marshall Cavendish, 2002) Daphnia have a hard external skeleton with jointed appendages and limbs. The head contains a large central eye which is made of two eyes joined together. Daphnia has two pairs of antennae which are used for swimming. Each daphnia has five pairs of limbs. These limbs lie in a certain space under the body bounded by the carapace. (Marshall Cavendish, 2002) A carapace is a hard upper shell or chitinous outer covering on the back of some animals. The daphnia is well preserved because of its shells which are composed of chitin. The usual size of this microorganism is about 0.2-0.3 mm; they look like flat disks. Their bodies are divided into three parts – head, thorax, and abdomen. The head is typically dome-shaped with five pairs of appendages. Among these five are two pairs of antennae; there is a small pair and a larger pair. The smaller pair of antennae serves as a sensory function and the larger one is used for swimming. The other three appendages’ purpose is to secure food they intake. (Michael Hutchins, 2003) The thorax holds four to six pairs of legs that are used for gathering food, filtering water, or grasping mates. There are over 400 species of daphnia and they are distributed worldwide. Daphnia uses their thoracic legs to produce a constant current of water; this allows them to filter food
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