Lecture 22 PDF - Animal Classification

Animals metazoans Eukaryotes Multicellular Heterotrophic Origin among the heterotrophioc protists Seen 565 million years ago Proifera Sponges No true tissues No symmetry Hermaphrodites Asexual regeneration 2 cell types ○ Choanocytes ○ Amoebocytes Cnidarians Diplobalstic Eumetazoa Two tissue layers ○...

Animals metazoans Eukaryotes Multicellular Heterotrophic Origin among the heterotrophioc protists Seen 565 million years ago Proifera Sponges No true tissues No symmetry Hermaphrodites Asexual regeneration 2 cell types ○ Choanocytes ○ Amoebocytes Cnidarians Diplobalstic Eumetazoa Two tissue layers ○ Endoderm ○ Ectoderm Two phases in life cycle ○ Polyp ○ Medusa Reproduce ○ Sexual ○ Asexual Nematocytes ○ Stinging organelles Bilateria Cephalization ○ Development of head ○ Sense organs in front Bilateral symmetry ○ Equally divided into 2 (left and Right) ○ Anterior and posterior ○ Direction in movement Triploblasty ○ Third tissue layer = mesoderm ◆ Forms muscle ◆ Supports organs ○ Coelomates ◆ Animals with body cavity that develops within the mesoderm ◆ Better control over movement of uids in body cavity, support of organs, digestion Protosomes ○ Blastopore - mouth ○ Lophotrochozoa ◆ atworms, annelids, molluscs ○ Ecdysozoa ◆ Arthropods and nematodes Deutrosomes ○ Blastopore - anus ○ Chordates Lophotrochozoa 1. Flatworms: Acoelomates ○ simplest bilateral animals ○ Parasites: tapeworms, ukes 2. Annelids: segmented worms fl fl fl ○ Segmentation= operate segments independently ◆ Coelom ◆ redundancy ○ Improves control over movement ○ Facilitates specialization of different body regions ○ Evolved multiple times ◆ Annelids ◆ Arthropods ◆ Chordates Mollusca Radula = feeding organ is unique to group Classes ○ Chitons ○ Bivalves ○ gastropods - snails, slugs ○ Cephalopods- squid, octopus Ecdysozoan Cuticle and molting Most species rich group 1. Roundworms ○ nematodes ○ Parasitic ○ Extremely abundant ○ Decomposers in soil 2. Arthropods ○ jointed appendages ○ Regional segmentation ○ Exoskeleton (chitin), molting ○ Open circulatory system ○ Most successful of all animal phyla ◆ 5 major groups: 1. trilobites 2. Chelicerates ○ horseshoe crabs, spiders, mites, ticks, scorpions 3. Millipedes and centipedes ○ millipedes - 2 pair legs ○ Centipedes- 1 pair legs 4. Crustaceans ○ crabs, lobsters, shrimp, isopods ○ Specialized appendages ○ 2 pair of antennae 5. Insects ○ most numerous and diverse of all animal species ○ M