CH 33 - Animal Evolution and Developmental Biology

Diploid Stage

Dominant life cycle stage in animals.

Haploid Gametes

Produced by meiosis in animals, mitosis in plants.

Asexual Reproduction

Reproduction without gamete fusion.

Binary Fission

Asexual reproduction in bacteria and archaea.

Budding

Asexual reproduction seen in yeast.

Fragmentation

Asexual reproduction in molds and sea stars.

Parthenogenesis

Development from an unfertilized egg.

External Fertilization

Sperm and egg unite outside the body.

Internal Fertilization

Sperm and egg unite inside the body.

Radial Symmetry

Multiple planes of symmetry around an axis.

Bilateral Symmetry

Single plane of symmetry divides body.

Cephalization

Nervous system concentration at body end.

Bilaterians

Animals exhibiting bilateral symmetry.

Blastopore

Opening in early embryonic development.

Deuterostomes

Organisms where blastopore becomes anus.

Coelom

Fluid-filled body cavity cushioning organs.

Amnion

Membrane allowing embryo development in fluid.

Larva

Free-living stage differing from adult form.

Juvenile

Developmental stage before reaching adulthood.

Homeostasis

Regulation of internal environment via feedback.

Ediacaran Period

Early animal fossils dating back 579 mya.

Cambrian Explosion

Rapid diversification of animal body plans.

Mass Extinctions

Events causing significant loss of biodiversity.

Brachiopods

Marine shelled animals prevalent in Ordovician.