BIOL 1010 Lecture Notes - Lecture 51: Gastrovascular Cavity, Cestoda, Arthropod
14 May 2017
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Gastrovascular cavity: leeches have a true coelom & complete digestive tract. Section 20. 11 arthropods are segmented animals with jointed appendages & an exoskeleton. Phylum arthropoda regarded as most successful animal phylum. Diversity & success related to their exoskeleton, & segmentation, jointed appendages. Exoskeleton is thick around the head where its main function is to house & protect the brain. It is paper thing & flexible in other locations. (joints of legs) Arthropod must periodically shed its old exoskeleton & secrete a larger one. Body of arthropod arise from grouped segments that fuse during development: head, thorax, & abdomen. In some (lobsters), exoskeleton of head & thorax is partly fused, forming a body region called the cephalothorax. (lobsters) head bears sensory antennae, eyes, & jointed mouth parts on the ventral side. Thorax bears a pair of defensive appendages (pincers) & 4 pairs of legs for walking.
