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CH 24 WHAT IS AN ANIMAL?.

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Presentation on theme: "CH 24 WHAT IS AN ANIMAL?."— Presentation transcript:

1 CH 24 WHAT IS AN ANIMAL?

2 CHARACTERISTICS OF ALL ANIMALS
Eukaryotic Multicellular Specialized cells (tissues & organs) Ingestive heterotrophs 1.5 million species

3 STRUCTURES FOR SUPPORT AND DEVELOPMENT
Exoskeletons – - hard or tough outer coverings - provide a framework for support - protect soft body tissues - prevent water loss - protection against predators Found on many invertebrates

4 Invertebrates – animals without backbones
% of animal species - most have an exoskeleton - exoskeletons are shed to make a new one as the animal grows - Some invertebrates, sea urchins and sea stars; have internal skeletons (endoskeletons)

5 Invertebrates Examples – animals without backbones
- Sponges, Cnidarians – first animals to evolve from a multicellular ancestor - Worms: flatworms, roundworms, segmented worms - Mollusks: octopus, snails, squids, clams - Arthropods: crustaceans, spiders, insects Echinoderms: sea stars, sea urchins, sand dollars - Invertebrate Chordates: lancelet, tunicates

6 Vertebrates – animals with a backbone
Endoskeleton – internal skeletons grow with the animal - calcium carbonate -sea urchins/sea stars (invertebrates) - cartilage – sharks - bone – fishes, amphibians, reptiles, birds, mammals

7 SEXUAL REPRODUCTION (MOST)
Sperm + Egg = Zygote Cleavage - - > zygote divides Embryo -> an organism in the early stages of development

8 CELL LAYERS (Most have three layers)
Ectoderm - outer layer (skin & nervous tissue) Endoderm - inner layer (digestive organs) Mesoderm – middle layer (muscles, circulatory, excretory and respiratory systems)

9 SYMMETRY Radial - round, or sphere shaped
Bilateral – right and left halves form a mirror image Asymmetrical – no definite shape

10 BODY PLANES Dorsal - back surface Ventral - belly surface
Anterior - top (head) Posterior - tail end

11 BODY CAVITIES Coelum - fluid-filled cavity - mesoderm (earthworms)
Acoelomate no body cavity (flatworms)


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