280 likes | 1.09k Views
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
E N D
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
bilaterally symmetrical larvae; radially symmetrical adults • eucoelomate • deuterostome Phylum Echinodermata • eumetazoan (true tissues)
Phylum Echinodermata Class Astroidae Class Ophiuroidae Class Echinoidae Class Holothuroidae Sea stars Brittle stars Sea urchins Sea cucumbers Class Crinoidae Crinoids
Phylum Echinodermata No circulatory system No respiratory system Excretion (N elimination) by diffusion Simple nervous system, no brain Water-vascular system
A Comparison of Early Development in Protostomes and Deuterostomes
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
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
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
Phylum Echinodermata Water Vascular System Tube feet & associated plumbing Used for walking, clinging to substrate & holding food
Class Echinoidea: sea urchins Slate pencil urchin Collector urchin Echinometra mathaei Echinothrix calamaris Colobocentrotus atratus
Class Holothuroidea: Sea Cucumbers Polyplectana kerfersteninii Holothuria atra
Class Asteroidea: Sea Stars Linckia sp. Maui, Hawaii Acanthaster planci Pin cushion
Mouth Tube feet Ambulacral groove Spines Starfish: Oral View
Pyloric stomach Stone canal Gonads Digestive glands Cardiac stomach Starfish Dissection: Skeleton Removed: Aboral View
Cardiac Stomach Gonads Ampullae Ambulacral Plates Starfish Arm: Digestive Glands Removed