What Is an Animal?

Biology

Post Falls HS

Characteristics

• Heterotroph

• Movement (and sessile)

• Energy from nutrients

• Eukaryotic with adaptations

Development of Animals• Fertilization of haploid gametes to form

zygote

• Blastula forms (hollow sphere)

• Gastrula forms (indents to give 2 layers)

• Ectoderm and endoderm

• Ectoderm forms skin and nerves

• Endoderm forms digestive lining

• Mesoderm forms later into muscles, reproductive and circulatory

Development (cont)

• Gastrula opening becomes mouth in protostomes

• Gastrula opening becomes anus in deuterostomes

• Some develop larval forms before adult

• Birth occurs after development reaches a satisfactory stage

• Viviparous, oviparous, ovoviviparous

Symmetry

• Balance in proportions of an organism

• General body plan or layout

• Asymmetry, radial symmetry, bilateral symmetry

Asymmetry

• Sponge• Irregular• No consistent design

Radial Symmetry

• Hydra, sand dollar• Central area with

parts radiating outwardly like spokes of a wheel

• Can be divided along any plane along its axis into relatively equal halves

Bilateral Symmetry

• Humans• Can be divided down

its length into mirror image halves

• Anterior, posterior, dorsal, ventral

• More muscular control so more efficient food gatherers

Bilateral Symmetry

Body Plans of Bilats

• Coelom – true body cavity that develops from the fluid-filled cavity inside the mesoderm

• Acoelomate, pseudocoelomate, coelomate

• Examples

Protection and Support• Exoskeleton• Endoskeleton

Protection and Support

• Vertebrate• Invertebrate