Invertebrates General

the 8 Phylums

• Porifera

• Cnidaria

• Platyhelminthes

• Nematoda

• Annelida

• Enchiodermeta

• Arthropda

• Mollusca

Protostomies

• Animal which develops mouth first anus second

• Represents determined development: in which fate of each cell of the organism has been determined

Deuterostomes

• Mouth develops second

• Undertimend development: each of the 8 cell embryo is separated and is capable of developing as a complete organism

Choanoflagellates x9

• Closest living relatives of animals

• solitary or colonial

• aquatic eukaryotes

• Most are sessile

• Each cell (choanocyte) has flagellum surrounded by collar of microvilli

• Beating flagellum draws water into collar

• microvilli collects mostly bacteria

• resemble sponge feeding cells

Animal x 5

• Multicellular

• Heterotrophic (gain energy through eating)

• Cells organized into cell layers and tissues

• Contain collagen

• Cells connected by “cell junctions”

Invertebrate diversity x 3

• 97% of all animals

• 35/36 Phyla

• estimated 8 million species

symmetry

none - Porifera

Radial - Cnidaria, Ctenophora

Bilateral - All the rest

Diploblast

Endoderm - non-living layer (mesoglea) - Ectoderm

• Radial symmetry

• Endoderm - becomes gut

• Ectoderm - becomes epidermis and nervous tissue

• greater tissue specialization and complexity than sponges

Triploblast

Endoderm - Mesoderm (forms organs) - Ectoderm