Deuterostomes

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Deuterostomes
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Deuterostomes

• Informal group of animal phyla
• Kingdom Animalia
• subkingdom Deuterostomes
• Phylum Chordata
• Phylum Echinodermata
• subkingdom Protostomes (later)

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Deuterostomes

• Embryonic development
• Zygote
• Cleavage
• 2 blastomeres ? 4 blastomeres ? 8 blastomeres
  ? 16 ? 32 ? 64 ? 128 ? 256 ? 512 ? . . . .
• Blastula
• Gastrula (gastrulation)

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Deuterostomes

• Gastrula (gastrulation)
• Forms two germ layers
• Ectoderm
• Endoderm
• Blastopore
• In deuterostomes forms anus
• Mouth develops at other end, later (2nd mouth)

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Deuterostomes

• Formation of Mesoderm and Coelom
• Pouches of endoderm bulge, pinch off to form
  Mesoderm (3rd germ layer) and gut pouch
  coelom.
• Cavity enclosed in mesoderm coelom
• Coelom body cavity completely enclosed by
  mesoderm not opening to outside.

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Two Major Phyla of Deuterostomes

• Phylum Chordata
• Notochord
• Dorsal nerve cord
• Pharyngeal arches clefts
• Post-anal tail
• Subphylum Vertebrata
• 7 or more classes, already studied
• Subphylum Urochordata ( tunicates)
• Subphylum Cephalochordata ( lancelets)

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Deuterostomes

• Phylum Chordata
• Subphylum Urochordata ( tunicates)
• Sessile, sac-like body
• Mouth, atriopore
• Tunic, protective outer cover
• Larva exhibits characters of Chordata

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Deuterostomes

• Phylum Chordata
• Subphylum Cephalochordata ( lancelets)
• Notochord extends tip of head to tip of tail

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Deuterostomes

• Phylum Echinodermata
• Pentaradial symmetry (NOT radial)
• Endoskeleton of ossicles
• CaCO3, calcium carbonate
• Water vascular system
• Sieve plate
• Tube feet

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Phyla of Deuterostomes

• Phylum Echinodermata
• Class Crinoids
• Class Sea Stars
• Class Brittle Stars
• Class Sea Urchins
• Class Sea Cucumbers