Deuterostomes

 

There is a trend toward increasing behavioral complexity

Two lineages split early:  (1) marine habitats, and (2) freshwater and terrestrial habitats

Marine:  Phylum Echinodermata

Freshwater and terrestrial:  Phylum Chordata

 

SLOs

  1. Be able to describe and discuss major advances in body structure and function that made invertebrates and vertebrates increasingly large and complex.
  2. Be able to explain adaptive radiations of the major classes of vertebrates.
    1. Know the distinguishing characteristics used to sort species into each major phylum. 
    2. Understand how members of each phylum are adapted to their environment and food source, e.g. by body plan or structures.

 

Phylum Echinodermata (“spiny skin”)

includes sea stars, sea urchins, sea lilies, sea cucumbers, brittle stars

 

bilateral larval symmetry, some adult radial symmetry

endoskeleton

madreporite/ tube feet/ water vascular system

 

Phylum Chordata

4 unique features:

  1. notochord
  2. dorsal hollow nerve cord
  3. pharyngeal slits
  4. muscular post-anal tail

 

Two invertebrate subphyla: 

            Urochoradata tunicates  (“sea squirts”)

            Cephalochordata (lancelets)

 Subphylum Vertebrata AKA craniate chordates

 

Early Paleozoic

(Agnasthostomes- jawless) Myxini (hagfish), Cephalaspidomorphi (lamprey)

 

(Gnasthostomes- jawed)

Fishes:  Half of all vertebrates !!

            From 400-450 mya, Paleozoic (Silurian; extensive diversification in Devonian)

Class Chondrichthyes

            Jaws, paired fins, gills for gas exchange only, bony teeth, lateral line, spiral valve,            internal fertilization, placoid scales

Major Classes of Osteichthyes: Actinopterygii (ray-finned; most successful), Actinistia

(lobe-finned fish), Dipnoi (lungfishes)

            swim bladder, operculum over gills, counter-current gas exchange,         internal and       external fertilization, thin flat scales, 2-chambered heart

 

Late Paleozoic

Tetrapods – “4 footed”

Class Amphibia  from 370 mya Devonian, in Carboniferous radiation/domination

            Skins can “breathe”, 3-chambered hearts, internal and external fertilization, no shelled eggs and no tough skin so tied to water/ damp, socialization and communication