Deuterostome Lab.key.pdf - Clade Deuterostomia Deuterostome...

This preview shows page 1 - 8 out of 28 pages.

Deuterostome CladogramSea stars, sea squirts, and sea serpents are all deuterostomes. (Ambulacraria) & Chordata Three “Phyla”: Echinodermata, Hemichordata, and Chordata Echinodermata+HemichordataCephalochordataUrochordataVertebrata+(Ambulacraria)ChordataClade Deuterostomia1
Deuterostome Synapomorphies*Simakov et al.2015. Hemichordate genomes and deuterostome origins. Nature527, 459–465Acorn Wormgill slitsAcorn Worms, Phylum Hemichordata, are burrowing marine filter feeders1.Gill slits: one of 2morphological synapomorphies. What’s the other?Coded for by pax1/9gene, (one of many orthologous deuterostome genes*) For respiration & filter feeding Arose in 500 myo common ancestor likely resembled this acorn worm. (70% of acorn worm genes have orthologs in us humans!)Clade Deuterostomia2
Echinoderm CladogramFeather stars: these colorful crinoids of coral & rock reefs can swim. Sea lilies: these stalked crinoids have an extensive fossil recordCrinoidsare basal echinoderms distinguished by an upward-facing mouth. They filter feed with tube feet.AsteroideaCrinoideaOphiuroideaEchinoideaHolothuroideaE c h i n o d e r m a t a“Phylum” EchinodermataCrinoidea3
Echinoderm Synapomorphies1. “Spiny skin” with multi-plated exoskeleton - see sea urchin lamp -plates are called ossicles; made of calcium carbonate 2.Water vascular systemwith tube feet for feeding and/or moving-ampullaesqueeze water to extend tube feet3. 5-part radial symmetry-in arms AND rows of tube feet“Phylum” Echinodermata4
Clades within “Phylum” EchinodermataSea Stars1.Extrude stomach to externally digest prey 2.Arms contain guts and gonads Tube feet for walking; have suckers at tips Respire using external “gills”AsteroideaOphiuroidea5
Brittle Stars & Basket Stars1.Pull themselves along with snake-like arms that have vertebraeTube feet for filter-feeding, lack suckers Segmented arms can detach 2.Central disk contain guts and gonads 3.Respire using bursal slitsand sacsAsteroideaOphiuroideaClades within “Phylum” Echinodermata6
Sea Urchins & Sand Dollars1.Chew with Aristotle’s Lantern2.They andsister clade Holothuroidea lack arms

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture