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Download Chapter 23 Kingdom Animalia – Invertebrates I. Characteristics of
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Chapter 23 Kingdom Animalia – Invertebrates I. Characteristics of Animals Multicellular – cells are usually arranged in organs or organ systems Heterotrophic – must have a food source Require oxygen to perform aerobic respiration Most are motile (able to move themselves) at some point in their life cycle Life cycle has some form of embryonic development Most reproduce sexually (some asexually) II. Radial Symmetry a. No true front or rear b. Unit repeats from the center III. Bilateral Symmetry a. Organism is the same on either side of a plane of symmetry b. Has a true front and rear IV. Phyla a. Phylum Porifera Animals with no symmetry, no tissues or organs. Range in size from tiny to large enough to sit in. Feed by engulfing particles (phagocytosis). Can reproduce sexually with larva or asexually by fragmentation. i. Example sponges b. Phylum Cnidaria All are aquatic, most are ocean dwelling. They have tissues. They have nematocysts, stinging darts, that are used to paralyze prey. They reproduce sexually by releasing gametes into the water. They have a nerve net for stimulation, but do not have a central nervous system. i. Class hydrozoa – hydrozoans ii. Class Anthozoa – Coral iii. Class scyphozoan – Jellyfish c. Phylum Platyhelminthes Have a simple digestive system. Most are hermaphrodites, but will reproduce sexually with another flatworm. i. Example – Turbellarians, flukes, and tapeworms d. Phylum Nematoda Thrive nearly everywhere. Have a complete digestive system. Have a partial body cavity where reproductive organs are found. Most are free-living, with few parasitic species. i. Roundworms, such as pin worms or hook worms e. Phylum Annelida – segmented worms Segments are repeating body sections. Many have setae (hairs or bristles) that help them move through soil. They have a complete gut, rudimentary brain (with a nerve cord), and a circulatory system. i. Example – Earthworms, leeches f. Phylum Mollusca Most have a hard shell covering a soft body. Have well developed organ systems. Have a brain i. Example – oysters, clams, squid, octopus, scallops, snails, slugs g. Phylum Arthropoda Have hardened exoskeletons, jointed appendages, respiratory structures, sensory structures, and most have a clear division of labor. i. All have jointed appendages (arms, legs, antennae, claws) ii. Class Arachnida – Spiders iii. Class Insecta – 1. have 3 parts: head, abdomen, thorax 2. Examples – Grasshoppers, ants iv. Class Crustacea – crawfish, crabs, shrimp h. Phylum Echinodermata They have spines or plates of calcium carbonate for protection. They have a well developed skeleton. They do not have a brain, but a nervous system is present. Water vascular system delivers water to tube feet for movement. i. Radial symmetry ii. Class Asteroidea – starfish i. Phylum Chordata i. Includes some invertebrates & all vertebrates ii. Subphylum Vertebrata – all vertebrates are in this subphylum. We will learn more about this in Chapter 24.
