Unit Four “Evolution, Natural Selection, & Adaptations” “Animals” 1

General Features of Animals 1. Hetertrophs – need to consume others 2. Eukaryotic – multicellular organisms 3. No Cell Walls – not rigid like plant cells 4. Active Movement – not sessile like plants 5. Diverse in Form – 99% are invertebrates 6. Diverse in Habitat 7. Sexual Reproduction 8. Embryonic Development – from one cell to many via mitosis 9. Unique Tissues – cells organized into structural units with specific function 2

Five Key Transitions in Body Plan 1. Evolution of Tissue 2. Evolution of Bilateral Symmetry – jellyfish (radial symmetry) versus dog 3. Evolution of a Body Cavity – organs located here 4. Evolution of Deuterostome Development – echinoderms (star fish) and chordates (humans etc.) form anus first during embryonic stage 5. Evolution of Segmentation – body made of segments/sections 3

The Geologic Time Scale 4

From Simple to Complex Phylum Porifera - Sponges 1. Asymmetrical bodies 2. no distinct tissue or organs 3. saclike body with two layers, with each layer containing pores 4. internal cavity within two layers contains food-filtering cells called “Choanocytes” 5. most live in marine environments 5

Phylum Porifera - Sponges 6

Phylum Cnidaria - Jellyfish 1. Radial symmetry 2. Soft, gelatin like 3. Stinging cells – “Cnidocytes” 4. Almost entirely marine 5. Primitive digestive system 7

Phylum Cnidaria – Jellyfish 8

Phylum Platyhelminthes - Flatworms 1. Solid and unsegmented 2. Bilateral symmetry 3. no body cavity 4. if present, digestive cavity has only one opening 5. Hermaphroditic (male and female sex organs) 6. marine, freshwater, or parasitic 9

Phylum Platyhelminthes - Flatworms 10

Phylum Nematoda - Roundworms 1. Unsegmented 2. Bilateral symmetry 3. Tubular digestive tract passing from mouth to anus 4. Very small 5. Abundant in soil, and some are animal parasites 11

Phylum Nematoda - Roundworms 12

Phylum Mollusca - Mollusks 1. Soft bodied 2. Body is divided into 3 parts: head-foot, visceral mass (body cavity w organs), & mantle 3. Many have shells 4. Snails (gastropods), Clams (bivalves), and Octopi (cephalopods) are all in this phylum 5. All possess a unique rasping tongue: “Radula” used mainly for the acquisition of food 6. Marine, freshwater, and terrestrial 13

Phylum Mollusca - Mollusks 14

Phylum Annelida – Earthworms 1. Segmented 2. Bilateral symmetry 3. Complete digestive tract 4. Marine, freshwater, and terrestrial 15

Phylum Annelida – Earthworms 16

Phylum Arthropoda - Insects 1. “Exoskeleton” made of chitin (skeleton on the outside, not the inside) 2. Most successful of all phyla 3. Segmented bodies w paired, jointed appendages 4. Most have wings 5. Mainly freshwater and terrestrial 17

Phylum Arthropoda - Insects 18

Phylum Echinodermata – Sea Stars 1. Adult bodies are radially symmetrical 2. “Pentamerous” (five parts) body plan 3. Unique water vascular system with tube feet (hydraulic system used for locomotion) 4. Able to regenerate lost body parts 5. All marine 19

Phylum Echinodermata – Sea Stars 20

Phylum Chordata – Fish through Mammals 1. Bilateral symmetry 2. Segmented with complete digestive system with two openings – mouth and anus 3. Backbone with advanced nervous system 4. Possess a tail at some stage of embryonic development 5. Marine, freshwater, and terrestrial 6. Fish, Amphibians, Reptiles, Birds, and Mammals 21

Phylum Chordata – Fish through Mammals 22