Animal Diversity and Human Embryological Development

Phylum Porifera

Sponges; lack tissues and symmetry.

Phylum Cnidaria

Includes jellyfish and corals; diploblastic.

Polyp

One body form of Cnidarians; sessile.

Medusa

Free-swimming body form of Cnidarians.

Phylum Platyhelminthes

Flatworms; unsegmented and bilaterally symmetrical.

Acoelomates

Animals lacking a true body cavity.

Phylum Nematoda

Roundworms; pseudocoelomates found in various habitats.

Eutely

Fixed number of cells in some nematodes.

Phylum Mollusca

Includes snails and octopuses; second most diverse.

Coelomates

Animals with a body cavity entirely within mesoderm.

Phylum Annelida

Segmented worms with a closed circulatory system.

Phylum Arthropoda

Most diverse animal group with jointed appendages.

Exoskeleton

Outer skeleton made of chitin in arthropods.

Phylum Echinodermata

Starfish; exhibit pentaradial symmetry as adults.

Phylum Chordata

Includes vertebrates; characterized by a notochord.

Cephalization

Development of a head region with sensory organs.

Protostomes

Mouth develops first during embryonic development.

Deuterostomes

Anus develops first during embryonic development.

Homeotic Genes

Control body plan organization along anterior-posterior axis.

Gastrulation

Process forming three germ layers from the blastula.

Organogenesis

Formation of organs from germ layers.

Neurulation

Development of the nervous system from the notochord.

hCG Production

Hormone secreted to maintain pregnancy.