Analysis #7 - Nabeel Siddiqui nhs256 Bio 206L Wed...

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Nabeel Siddiqui nhs256 Bio 206L Wed. 9:00-1:00 (49530) 3/10/2010 Representative Invertabrates Exercise # 7: Analysis 1. Chelapeds - Helps animal grasp its food. Walking legs - located on the ventral part of the thorax, and helps crayfish move or swim. (locomotion) Maxillapeds - Helps crayfish grasp food, appendage responsible for sensing touch and taste. Mandibles - Located in the mouth, it’s responsible for crushing food. Genital Pore - releases gamete cells for reproduction. Nephridiophore - External pore where the crayfish excretes its nitrogenous waste. Located towards the head of the crayfish. Eye - Help crayfish sense movement of pray or food. (Square segments) Uropod/Telson - Help animal swim, tail fin of crayfish. 2. The digestive system of a crayfish that help it pass food and nutrients from mouth to anus consists of many internal structures. First the maxillae help the animal pass food into its mouth. Once eaten the food passes through a short esophagus and into the stomach which consists of two parts. First food enters the cardiac stomach, which adds digestive enzymes and a gastric mill, and help break down the food. The enzymes are added from the digestive glands located proximal to the stomach. The pyloric stomach filters undigested food and prevents it from entering the crayfish’s intestines. Once it reaches the intestine, food travels through the mid gut and hind gut and is finally excreted through the anus. 3. When a crayfish see’s food through its eyes, it doesn’t actually have a clear, focused picture of the food. The square facets allow the crayfish to track its movement in the water and initiate a proper response. The nerves that connect the
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eyes to the cerebral ganglion carry a signal which then shoots down the ventral nerve chord which lies right around the esophagus. At each segment of the crayfish, there are ganglia which have separate nerves extending outwards towards each corresponding appendage. The signal then travels through all the appropriate nerves and activates the appendages that allow the crayfish to swim or
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Analysis #7 - Nabeel Siddiqui nhs256 Bio 206L Wed...

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