Deuterostomes

Developmental patterns of Deuterostomes

• cleavage - initial first divisions in development

• Coelom development - how coelom develops

• Fate of blastopore - butt of mouth

Deuterostome 3 traits

• Triploblastic

• Coelomate

• internal skeletons (when they have one)

Clades

• Echinoderms

• Hemichordates

• Chordates

Ambulacraians

Echinoderms and Hemichordates

Ambulacrarian traits

Ciliated and bilaterally symmetrical larvae

Hemichordate adults

bilaterally symmetrical

Echinoderms adults

pentaradial symmetry

Echinoderms

• Internal skeleton of fused calcified plates

• Water vascular system: network of water-filled canals leading to extensions called tube feet

  • functions in gas exchange, locomotion, and feeding

  • water enters through madreporite

Crinoids

• Sea lilies attach to the substrate by a stalk

• feather stars grasp substratum for movement

Echinozoans

Sea urchins

• Lacks arms, uses spines to move

• catches plankton with tube feet

Sea cucumbers

• lacks arms

• has a front (mouth) and a back (anus)

• tube feet used for movement but more to anchor to substrate

Asterozoans

Sea stars

• Gonads and digestive organs located in the arms

• tube feet have suction cups for locomotion, gas exchange, and attachment

Brittle starts

• flexible arms

• gonads and viscera are in central disc

• tube feet lack suction cups