Phylum Echinodermata • Deuterostomia – Anus forms from or near blastopore – Mouth forms secondarily
Jan 05, 2016
Phylum Echinodermata
• Deuterostomia– Anus forms from or near
blastopore– Mouth forms secondarily
Protostomes vs Deuterostomes
Plutei
Echinoderm Development
• Metamorphosis of bilaterally symmetric larvae to pentaradial adults
Deuterostome Phylogeny
Echinoderm Phylogeny
Echinoderm Symmetry• Primary bilateral symmetry
– Larval forms– Some adult forms
• Secondary pentaradial symmetry– 5 radial divisions of major
organ systems
Phylum Echinodermata
• Spiny skin• Endoskeleton
– Dermal ossicles– CaCO3, Ca2(PO3)2
Pedicellaria
Phylum Echinodermata
• Water vascular system
Water Vascular System & Tube Feet
Tube Feet
Hemal Canals
Class Asteroidea
• Central body disc• Most frequently 5 arms• Regeneration
Starfish & Sea Stars
Asteroidea Anatomy
Asteroidea Anatomy
Regenerating Arms
Commensals of Echinoderms
Class Ophiuroidea
Brittle StarsSea baskets
Reduced central discReduced tube feet
Class OphiuroideaSea baskets
Basket stars
Ophiuroidea Anatomy
Ophiuroidea Anatomy
Class Echinoidea
Sand dollars
Sea urchins
Sea biscuits
Echinoid Anatomy
Echinoid Mouth – Aristotle’s Lantern
Class HolothuroideaSea Cucumbers
Holothuroidea Anatomy
Holothuroidea Defense Reaction
• Eversion of the respiratory tree and lower intestine
• Some species produce toxins
Class Crinoidea
Feather StarsSea Lillies
Sessile Crinoids
Swimming Crinoid
Crinoid Anatomy