Introduction to Animals Invertebrate Evolution and Diversity Chapter 25 Chapter 26.1

Introduction to Animals Chapter 25

Characteristics of Animals Kingdom – Animalia Multicellular Heterotrophic Eukaryotic Lack cell wall

Types of Animals Invertebrates Lack backbone or vertebral column Sea stars, worms, jellyfish, insects

Chordates Exhibit four characteristics during at least one stage of life Dorsal, hollow nerve cord Notochord Tail that extends beyond anus Pharyngeal pouches Lancelet

Chordates with backbones = Vertebrates Fishes, amphibians, reptiles, birds, mammals

What Animals Do to Survive Maintain homeostasis by gathering and responding to information Feedback inhibition

Obtain and distribute oxygen and nutrients Collect and eliminate CO2 and waste Reproduce

Animal Development Animals have a wide variety of forms. The following developmental factors determine the body plan: Levels of organization : cells, tissue, organ, organ systems Arrangement of Germ layers: differentiate into different tissue types: Endoderm (inner): digestive tract mesoderm (middle): muscles, blood ectoderm (outer): skin, nervous system

Development, cont. Overall Patterns of Embryological Development Protostomes Blastopore becomes mouth Most invertebrates Deuterostomes Blastopore becomes anus Chordates, Echinoderms (sea stars)

Development, cont. Body Cavity Formation Coelom – completely lined with tissue derived from mesoderm Acoelom – lack a body cavity Pseudocoelom – partially lined with mesoderm

Development, cont. Body symmetry: Radial body parts extend from a central point Divides into equal halves Bilateral Right and left sides are mirror images of each other Distinct anterior and posterior ends and dorsal and ventral sides

Segmentation Cephalization Limb Formation Repeating Parts Worms, insects, vertebrates Cephalization concentration of sense organs and nerve cells at anterior end (head) Limb Formation Legs, Flippers, Wings

Cladogram of Animals Phyla defined by: Ex. Phylum Arthropoda Adult body plans Patterns of embryological development Ex. Phylum Arthropoda Body plan bilateral symmetry Segmentation Cephalization External skeleton Jointed legs

Invertebrate Evolution and Diversity Cladogram of invertebrates determined by evolutionary relationships among major groups sequence of evolution of important features

Sponges Phylum: Porifera (“pore bearers”) Most ancient member of kingdom Animalia Multicellular, heterotrophic, lack cell walls, contain few specialized cells Clade Metazoa

Cnidarians jellyfishes, sea fans, sea anemones, hydras, corals Aquatic, soft-bodied, carnivorous, radially symmetrical, stinging tentacles around mouths Simplest animals with body symmetry and specialized tissues

Nematoda (Roundworms) Unsegmented worms Pseudocoeloms Specialized tissues and organs Digestive tract with two openings

Platyhelminthes Flatworms Soft Unsegmented Have tissues and internal organ systems Bilateral symmetry Cephalization Do not have coeloms

Annelids earthworms, some marine worms, leeches Segmented bodies True coelom lined with tissue derived from mesoderm

Arthropods Phylum: Arthropoda – spiders, centipedes, insects, crustaceans Bodies divided into segments Exoskeleton Cephalization Jointed appendages

Mollusks Phylum: Mollusca – snails, slugs, clams, squids, octopi Soft-bodied Internal or external shell True coeloms surrounded by mesoderm and complex organ systems Free-swimming larva

Echinoderms Phylum: Echinodermata – sea stars, sea urchins, sand dollars Spiny skin Internal skeleton Water vascular system – used for walking and gripping prey Five-part radial symmetry

Animals Chordates Invertebrates Cnidaria Hexacorallia R. daphneae Other invert. Other Cnidaria Other Hexacorallia Order: Class: Phylum: Sub-kingdom: Kingdom: