NatSci360 Deuterostomia

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Natural Sciences 360 Legacy of Life Lecture 9 Dr.
Stuart S. Sumida
DEUTEROSTOMIA The Echinoderms
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Choanoflagella Porifora Placozoa Ctenophora C
nidaria Protostomia Pterobranchia Echinodermata
Hemichordata Chordata
Animalia
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Recall Bilateralia Includes two great groups
of animals Protostomia (means 1st
mouth) Deuterostomia (means 2nd mouth)
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• ECHINODERMATA
• Characterized by
• Radial symmetry as adults (bilateral as larvae)
• Water-vascular system

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There are many groups of echinoderms. The moist
important extant groups (those that remain alive)
are Crinoidea (sea lilies) Asteroidea
(starfishes) Ophiuroidea (brittle
stars) Echinoidea (sea urchins) Holothuroidea
(sea cucumbers)
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Crinoidea Asteroidea Ophiuroidea Echinoidea
Holothuroidea
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The echinoderm skeleton is INTERNAL, and composed
of elements called ossicles.
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Crinoidea Asteroidea Ophiuroidea Echinoidea
Holothuroidea
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Crinoidea Asteroidea Ophiuroidea Echinoidea
Holothuroidea
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Crinoidea Asteroidea Ophiuroidea Echinoidea
Holothuroidea
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Crinoidea Asteroidea Ophiuroidea Echinoidea
Holothuroidea
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Crinoidea Asteroidea Ophiuroidea Echinoidea
Holothuroidea
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DEUTEROSTOMIA Phylum Chordata
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Choanoflagella Porifora Placozoa Ctenophora C
nidaria Protostomia Pterobranchia Echinodermata
Hemichordata Chordata
Animalia
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Recall from last week Bilateralia Includes two
great groups of animals Protostomia (means 1st
mouth) Deuterostomia (means 2nd mouth)
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• The best known of the Deuterostomia
• Pterobranchia
• Echinodermata
• Hemichordata
• Chordata

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PHYLUM CHORDATA Deuterostomes with GILL
SLITS (Orginal function of gill slits NOT for
breathing for FILTER FEEDING.)
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• PHYLUM CHORDATA
• Deuterostomes with the following synapomorphies
• Pharyngeal gill slits
• Dorsal hollow nerve cord
• Notochord
• Post-anal tail

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• PHYLUM CHORDATA
• Includes the following subphyla
• Urochordata
• Cephalochordata
• Vertebrata
• (People used to think Hemichordata were included,
  but they turn out to be the sistergroup.)

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SUBPHYLUM UROCHORDATA
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How can something like this be related to
chordates like us? Addition of a new life stage
a mobile larval stage. CAENOGENESIS
Interpolation of a new life stage into the
lifecycle.
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The new larval stage of a urochordate
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UROCHORDATE Metamorphosis from larva to adult
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Adult urochordate
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Some urochordates stay larval all life long, but
they become sexually mature an example of
NEOTONY. Where else have we heard of neotony?
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More fish-like PHYLUM CEPHALOCHORDATA
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DHNC Notochord Pharynx Gill slits Muscle
blocks
Cephalochordate Branchiostoma (Amphioxus)
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So, then whats a vertebrate?
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