ANIMAL DIVERSITY I (ANIMAL CHARACTERISTICS & BODY PLANS)

Animals

Eukaryotic, multicellular heterotrophs that ingest food

Extracellular matrix (ECM

Network outside cells that provides support and communication

Heterotrophic

Obtains energy by consuming other organisms

Ingestion

Taking in food for digestion

Metamorphosis

Developmental transformation during life cycle

Hox genes

Genes that control body plan and spatial orientation

Cambrian explosion

Rapid diversification of animal life ~542 million years ago

Ediacaran biota

Early simple multicellular organisms before Cambrian period

Tissues

Groups of similar cells performing a function

Diploblastic

Animals with two germ layers (ectoderm and endoderm)

Triploblastic

Animals with three germ layers (ectoderm, mesoderm, endoderm)

Ectoderm

Outer germ layer forming skin and nervous system

Mesoderm

Middle layer forming muscles, bones, and organs

Endoderm

Inner layer forming digestive system

Symmetry

Arrangement of body parts

Asymmetrical

No body symmetry

Radial symmetry

Body organized around central axis

Bilateral symmetry

Body divided into right and left halves

Protostomes

Animals where mouth forms first during development

Deuterostomes

Animals where anus forms first during development

Cleavage

Pattern of cell division in early embryo

Spiral cleavage

Diagonal cell division in protostomes

Radial cleavage

Parallel/perpendicular division in deuterostomes

Determinate cleavage

Cell fate fixed early in development

Indeterminate cleavage

Cells can develop into complete organism

Coelom

Fluid-filled body cavity completely lined by mesoderm

Pseudocoelom

Body cavity not fully lined by mesoderm

Acoelomate

Animal without a body cavity

Segmentation

Body divided into repeating units

Blastopore

Opening formed during gastrulation