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Echinoderms: Sea Stars

Echinoderms: Sea Stars. 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

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Echinoderms: Sea Stars

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  1. Echinoderms: Sea Stars • 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

  2. bilaterally symmetrical larvae; radially symmetrical adults • eucoelomate • deuterostome Phylum Echinodermata • eumetazoan (true tissues)

  3. Phylum Echinodermata Class Astroidae Class Ophiuroidae Class Echinoidae Class Holothuroidae Sea stars Brittle stars Sea urchins Sea cucumbers Class Crinoidae Crinoids

  4. Phylum Echinodermata No circulatory system No respiratory system Excretion (N elimination) by diffusion Simple nervous system, no brain Water-vascular system

  5. A Comparison of Early Development in Protostomes and Deuterostomes

  6. Early Embryonic Development

  7. Starfish Development Unfertilized egg 2 blastomeres 4 blastomeres After fertilization & 1st cleavage 2nd cleavage 6th cleavage, next slide 3rd cleavage 5th cleavage 4th cleavage 32 blastomeres 16 blastomeres 8 blastomeres

  8. Starfish Development (continued) 64 blastomeres Non-motile blastula Ciliated blastula * blastula is same size as unfertilized egg Next slide blastopore Gastrula: Archenteron, no mesenchyme Gastrula: During invagination Gastrula: Beginning invagination

  9. Starfish Development (continued) Gastrula: Archenteron with mesenchyme Early bipinnaria larva, lateral view Late gastrula: lateral view 2nd opening becomes mouth blastopore becomes anus Late bipinnaria larva, lateral view Young starfish Brachiolaria larva

  10. Phylum Echinodermata Water Vascular System Tube feet & associated plumbing Used for walking, clinging to substrate & holding food

  11. Starfish water vascular system

  12. Class Echinoidea: sea urchins Slate pencil urchin Collector urchin Echinometra mathaei Echinothrix calamaris Colobocentrotus atratus

  13. Class Holothuroidea: Sea Cucumbers Polyplectana kerfersteninii Holothuria atra

  14. Class Asteroidea: Sea Stars Linckia sp. Maui, Hawaii Acanthaster planci Pin cushion

  15. Class Ophiuroidea: Brittle Stars

  16. Class Crinoidea: Feather Stars

  17. Starfish Dissection: Schematic View

  18. Mouth Tube feet Ambulacral groove Spines Starfish: Oral View

  19. Pyloric stomach Stone canal Gonads Digestive glands Cardiac stomach Starfish Dissection: Skeleton Removed: Aboral View

  20. Cardiac Stomach Gonads Ampullae Ambulacral Plates Starfish Arm: Digestive Glands Removed

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