Echinoderms
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Transcript of Echinoderms
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Goals of the lab:
• to introduce general characteristics of the phylum Echinodermata
• to understand the embryological differences between protostomes and deuterostomes
• to observe initial stages of embryo development, using prepared slides of starfish embryos
• to examine external and internal features of the starfish, as a representative of the phylum Echinodermata
Echinoderms
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Phylum Echinodermata
• eumetazoan (true tissues)
• bilaterally symmetrical larvae; radially symmetrical adults
• eucoelomate
• deuterostome
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Phylum Echinodermata
Class Astroidae
Class Ophiuroidae
Class Echinoidae
Class Holothuroidae
Class Crinoidae
Sea stars Brittle stars
Crinoids
Sea urchins Sea cucumbers
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Phylum Echinodermata
No circulatory system
No respiratory system
Excretion (N elimination) by diffusion
Simple nervous system, no brain
Water-vascular system
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A Comparison of Early
Development in Protostomes
and Deuterostomes
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Early Embryonic Development
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Unfertilized egg
Starfish Development
2 blastomeres
After fertilization
& 1st cleavage
4 blastomeres
2nd cleavage
8 blastomeres
3rd cleavage
16 blastomeres
4th cleavage
32 blastomeres
6th cleavage, next slide
5th cleavage
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Starfish Development (continued)
64 blastomeres
Non-motile blastula Ciliated blastula
* blastula is same size as unfertilized
egg
Gastrula: Beginning invagination
blastopore
Gastrula: During invagination
Gastrula: Archenteron, no
mesenchyme
Next slide
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Starfish Development (continued)
Gastrula: Archenteron with mesenchyme
Late gastrula: lateral view
Early bipinnaria larva, lateral view
Brachiolaria larvaYoung starfish
Late bipinnaria larva, lateral view
blastopore becomes
anus
2nd opening becomes
mouth
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Sea urchin larvae: pluteus Starfish larvae: BipinnariaSea cucumber &
Crinoid:doliolaria larvae
Brittle star larvae: pluteus
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Phylum Echinodermata
Tube feet & associated plumbing
Used for walking, clinging to substrate & holding food
Water Vascular System
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Starfish water vascular system
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Class Echinoidea: sea urchins
Echinometra mathaei
Collector urchin Echinothrix calamaris
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Class Echinoidea: sea urchins
Diadema
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Class Echinoidea: sea urchins
Slate pencil urchin
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Colobocentrotus atratus
Class Echinoidea: sea urchins
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Class Holothuroidea: Sea Cucumbers
Holothuria atra
Polyplectana kerfersteninii
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Class Holothuroidea: Sea Cucumbers
http://www.youtube.com/watch?v=Fw2DrbhOA-M
Pearlfish in seacucumber
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Linckia sp.
Class Asteroidea: Sea Stars
Pin cushion
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Class Asteroidea: Sea Stars
http://www.arkive.org/crown-of-thorns-starfish/acanthaster-planci/video-00.html
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Class Ophiuroidea: Brittle Stars
Ophiocoma erinaceus
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Class Crinoidea: Feather Stars
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Starfish Dissection: Schematic View
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Starfish: Oral View
Mouth
Ambulacral groove
Spines
Tube feet
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Starfish Dissection: Skeleton Removed: Aboral View
Stone canal
Digestive glands
Gonads
Pyloric stomach
Cardiac stomach
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Starfish Arm: Digestive Glands
Removed
Ambulacral Plates
Ampullae
Cardiac Stomach
Gonads
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