'Acorn worms' diaporamas de présentation

A mosaic of conserved and radically changed developmental features A. Conserved

Modifications of the developmental plan fall into two general categories in the evolution of development: heterotopies and heterochronies. Define these two categories and provide an example of each that was discovered in studies of the Australian sea urchins of the genus Heliocidaris.

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How do these taxa relate?

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Phylum Hemichordata

Phylum Hemichordata. Marine worms Share characteristics with echinoderms and chordates Deuterostomes (radial cleavage) Pharyngeal gill slits Some have dorsal, hollow nerve cord. Class Enteropneusta. Acorn worms ~ 70 species Live in burrows in fine sediments. Acorn worms.

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Chapter 7

Chapter 7. Phylum Hemichordata Phylum Chordata. Phylum Hemichordata. Characteristics: Rare group, but these worms seem to span a gap between invertebrates and more advanced chordate animals

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