23.1 animal characteristics animals. 23.1 animal characteristics multicellular heterotrophic lack...

23.1 Animal Characteristics

Animals


• Multicellular• Heterotrophic• Lack cell walls• Sexual Reproduction• Movement• Specialization – adaptation for a cell for a

particular functionCells tissues organs organ systems


Body Structure

• Dorsal – top• Ventral – bottom• Anterior – head• Posterior - Tail


Body Symmetry

• Asymmetry – no symmetry

• Radial – arrangement of body parts around a central axis

- top & bottom, no front, back, or right & left sides

• Bilateral symmetry – 2 similar halves on either side of a central plane

23.2 Animal Diversity

23.1 Animal Characteristics 23.2 Animal Diversity

Radial Symmetry – allows for organism to take in stimuli from all sides


Bilateral Symmetry – adaptation for movement


Cephalization

• concentration of sensory & brain structures in the anterior region

No-cephalization



Fertilization

• Gamete + Gamete = Zygote• Sperm membrane fuses with egg membrane

– causes an electrical shock that blocks entry by other sperm

• Sperm nucleus merges with egg nucleus



Cleavage – cell divisions of the zygote immediately following fertilization

Rapidly increases # of cells, but cells do not grow in size• Increases surface area-to-volume ratio• Continues until they form a hollow ball of cells –

blastula• Central cavity - blastocoel



Gastrulation – blastula collapses inward

• Blastopore – infolded region - will function as the gut • Gastrula – multilayered embryo• Deep cavity is formed – archenteron – embryonic stem cells

Ectoderm – outer germ (cell) layer• Skin, hair, etc.

Endoderm – inner germ layer• Digestive system

Mesoderm – layer between ectoderm & endoderm

• Muscular and Skeletal systems



Patterns of Development

• Protostomes – blastopore first develops into a mouth

• Deuterostomes – blastopore first develops into anus



Types of Body Cavities

• Acoelomates – body cavity is absent– Flatworms

• Pseudocoelomate – mesoderm lines the fluid-filled coelom (body cavity)

• Coelomates – mesoderm lines the body cavity and surrounds and supports the gut


23.1 animal characteristics animals. 23.1 animal characteristics multicellular heterotrophic lack...

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