Evaluate Basic External Animal Anatomy and Morphology - AgriSETA

Evaluate Basic External Animal Anatomy and MorphologyPrimary Agriculture NQF Level 1 Unit Standard No: 11617336oEyesOn the outside of the 2 pairs of antennae is a short stalk with acompound eye at the tip. The stalks can fold into grooves in thecarapace to shield them from damage.oThe mouthpartsThe crab has biting mouthparts - one pair of hard jaws, two pairsof soft jaws and three pairs of jaw-feet (maxillipodes - footlikestructures of the upper jaw).oThe legsFive pairs of jointed legs are attached to the cephalothorax.The first pair is usually larger and stronger than the rest and endin strong pincers, which are used for holding the prey. The otherfour pairs end in strong claws and are used for movement.oBreathing gills The abdomenCrabs breathe by means of gills in a chamber on the side of thecephalothorax. In each chamber are six gills. They are structuredthat the crab can live in and outside water.In an adult crab the abdomen is permanently folded in under thecephalothorax. In the male the abdomen is roughly triangular, while in afemale it is more dome-shaped. The abdomen consists of six clearlydefined segments. If you lift it you will see the following:• Swimmerets (peapods - long, flat reproductive structurescovered with hairs)These are long, flat structures covered in hairs. Two pairs occur inmales and four pairs in females. They are used in reproduction. Theanus is on the last segment.Version: 01 Version Date: July 2006