General Zoology

abdomen adult amino acids amphibians animals annelids anus aquatic arthropods birds blood body wall bones brain burrows cavity cells chromosomes cilia ciliated circulatory system Class coelom contains crustaceans ctenophores cuticle digestive tract dorsal duct echinoderms eggs embryo enzymes epidermis esophagus excretory eyes feed female fibers Figure fins fishes fluid fossil fresh water freshwater frog gametes gastrula genes gill glands gonads hormone human illus insects intestine invertebrates jaws larvae layers legs limbs living lophophore lungs male mammals mantle marine membrane molecules mollusks molt mouth muscles nephridia nerve cord nervous system notochord occur Order organs oviduct oxygen pairs parasitic pharynx phyla Phylum plants posterior produce protein protozoans reproductive reptiles respiration segments sensory shell skeleton skin slender somites species sperm sponges structure Subclass Suborder surface swim tail teeth tentacles tion tissue tube usually ventral vertebrates vessels wings worms