Animal Characteristics (32.1)

Animals

Multicellular, heterotrophic eukaryotes with embryonic layers

Nutritional Mode

Animals ingest organic molecules for nutrition

Cell Structure

Animals lack cell walls and use collagen for structural support

Cell Specialization

Animals have tissues and specialized cells like muscle and nerve cells

Reproduction

Most animals reproduce sexually with a dominant diploid stage

Cleavage

Succession of mitotic cell divisions during animal development

Blastula

Hollow ball stage of embryonic development in animals

Gastrulation

Production of embryonic tissues that develop into adult body parts

Larva

Sexually immature form of an animal, morphologically distinct from adult

Metamorphosis

Developmental transformation from larva to juvenile

Developmental Genes

Genes that regulate the expression of other genes during animal development

Hox Genes

Homeobox-containing genes that control the development of animal embryos