Echinoderms sea stars
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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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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

  • to examine external and internal features of the starfish, as a representative of the phylum Echinodermata


Echinoderms sea stars

  • bilaterally symmetrical larvae; radially symmetrical adults

  • eucoelomate

  • deuterostome

Phylum Echinodermata

  • eumetazoan (true tissues)


Echinoderms sea stars

Phylum Echinodermata

Class Astroidae

Class

Ophiuroidae

Class

Echinoidae

Class

Holothuroidae

Sea stars

Brittle stars

Sea urchins

Sea cucumbers

Class

Crinoidae

Crinoids


Echinoderms sea stars

Phylum Echinodermata

No circulatory system

No respiratory system

Excretion (N elimination) by diffusion

Simple nervous system, no brain

Water-vascular system


Echinoderms sea stars

A Comparison of Early Development in Protostomes and Deuterostomes


Echinoderms sea stars

Early Embryonic Development


Echinoderms sea stars

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


Echinoderms sea stars

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


Echinoderms sea stars

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


Echinoderms sea stars

Phylum Echinodermata

Water Vascular System

Tube feet & associated plumbing

Used for walking, clinging to substrate & holding food


Echinoderms sea stars

Starfish water vascular system


Echinoderms sea stars

Class Echinoidea: sea urchins

Slate pencil urchin

Collector urchin

Echinometra mathaei

Echinothrix calamaris

Colobocentrotus atratus


Echinoderms sea stars

Class Holothuroidea: Sea Cucumbers

Polyplectana kerfersteninii

Holothuria atra


Echinoderms sea stars

Class Asteroidea: Sea Stars

Linckia sp.

Maui, Hawaii

Acanthaster planci

Pin cushion


Echinoderms sea stars

Class Ophiuroidea: Brittle Stars


Echinoderms sea stars

Class Crinoidea: Feather Stars


Echinoderms sea stars

Starfish Dissection: Schematic View


Echinoderms sea stars

Mouth

Tube feet

Ambulacral groove

Spines

Starfish: Oral View


Echinoderms sea stars

Pyloric stomach

Stone canal

Gonads

Digestive glands

Cardiac stomach

Starfish Dissection: Skeleton Removed: Aboral View


Echinoderms sea stars

Cardiac Stomach

Gonads

Ampullae

Ambulacral Plates

Starfish Arm: Digestive Glands Removed


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