BIOL 2003 Lecture Notes - Lecture 12: Water Vascular System, Deuterostome, Tube Feet
Deuterostomia
October 19-21, 2015
Deuterostome Embryogenesis:
1. Radial cleavage
• Ends with formation of a blastula
• Spindle axes are parallel or at right angles to polar axis of oocyte
2. Regulative Embryo
• Each cell generates complete embryo
3. Fate of blastopore (becomes anus first)
• Mouth is developed after the anus
4. Enterocoelous (outpocketing) coelom formation
• Coelom forms by outpocketing of the mesoderm
Two Unique Phyla: Chaetognatha and Xenoturbellida *not covered
Phyla Enchinodermata
• Tissue: organ system
• Symmetry: pentaradial symmetry in adults
• Body Cavity: coelomate
• Development: triploblasts deuterostome
• Segmentation: not present
Unique Features:
• Spiny skin
• Exclusively marine; mostly benthic
• 7000+ species; 5 classes
• lack cephalization
• 1. Calcareous endoskeleton
o ossicles (calcareous plates) connected by collagen
▪ catch collagen – liquid to solid
o Part of a unique coelom called the stereom
• 2. Water vascular system
o Hydraulic system – canals and tube feet
o Functions: respiration, excretion, locomotion, and feeding
o Series of Canals: outside in
▪ Madreporite
▪ Stone canal
▪ Ring canal
▪ Radial canal
▪ Ampullae
▪ Podia (tube feet)
• 3. Pedicellariae
o On aboral surface
o Cleaning, food capture, defense
• 4.Papulae (dermal branchiae)
o also called skin gills
o projections of thin-walled coelom
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