bi 212: lecture 6 phylum echinodermata. phylum echinodermata: spiny-skinned
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Bi 212: Lecture 6Bi 212: Lecture 6
Phylum Echinodermata
Phylum Echinodermata:Phylum Echinodermata:Spiny-skinnedSpiny-skinned
Evolutionary relationshipsEvolutionary relationships
and HOX genes
Deuterostomes!
Echinodermata: 4 key featuresEchinodermata: 4 key features Calcareous internal skeleton
Parts: Plates, spines and pedicellariae
Why considered “internal”? Symmetry
Bilateral symmetry (larvae) Pentamerous radial symmetry
(adults) Water vascular system
Derived from coelom Layout (next slide shows…) Key function: tube foot control Other functions
Mutable connective tissue What does this mean?
Body plan: Other aspectsBody plan: Other aspects Perivisceral coelom
Houses organs Gas exchange Hydrostatic skeleton
Digestive system Can be highly branched Complete in some
Nervous system No brain Branches parallel water
vascular system Sensory (sea stars)
Eye spots Receptors associated with
tube feet No circulatory system No excretory system
Class Asteroidea: Class Asteroidea: sea starssea stars
Feeding Stomach eversion Enzymes
Respiration Tube foot ? ? Dermal papulae
? Protection
Mechanisms?
Class Echinoidea:Class Echinoidea:Sea urchins and othersSea urchins and others
Feeding Aristotle’s lantern Main type of food?
Respiration Tube foot ? ? Peristomial gills ?
Protection Mechanisms?
Class Holothuroidea: Sea Class Holothuroidea: Sea cucumberscucumbers
Symmetry? Feeding
Deposit feeders (what does this mean?)
Respiration Respiratory tree?
Water entry into tree?
Body surface ? Tube feet ? ?
Protection Cuvarian tubules Evisceration…
Class Ophiuroidea:Class Ophiuroidea:Brittle stars, basket starsBrittle stars, basket stars
Class CrinoideaClass CrinoideaSea liliesSea lilies