Phylum Echinodermata: Deuterostome Group
• All marine
• Deuterostomes
• Structure- Dermal endoskeleton
• Locomotion-Water-vascular system
• Pedicellariae and dermal branchiae
• Cephalization- poor
• Segmentation- poor
• Pentaradiate symmetry in adults
• Bilateral symmetry in larvae
Class Ophiuroidea
1. Ambulacral groove- absent; has bursae-openings on each arm
2. Structure- five arms sharply marked off from central disc
3. Oral surface – 5 jaws and 5 oral shield (buccal shields); one oral
shield modified into madreporite plate
4. Tube feet –modified tentacles without suckers
5. Ex: Brittle stars
Class Asteroidea
1. Structure- star shaped with arms not marked off from central disc
2. Ambulacral groove- open
3. Tube feet- on oral side with suckers
4. Anus and madreporite- on aboral side
5. Ex: starfish
Class Echinoidea
1. Structure- globular or disc shaped without arms
2. Movable spines and compact skeleton
3. Ambulacral grooves- closed and covered by ossicles
4. Tube feet- with suckers
5. Ex: Sea urchins and sand dollars
Class Holothuroidea
1. Structure- cucumber shaped with no arms
2. Ambulacral grooves- closed
3. Anus- present and madreporite plate internal
4. Tube feet- with suckers
5. Ex: Sea cucumbers
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Class Asteroidea
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Class Holothuroidea
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Class Echinoidea
Sand Dollar
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