Transcript Deuterostomate Animals

The Deuterostomes
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Embryonic blastopore becomes the anus.
Three body layers.
True coelom.
Dorsal nerve cord.
Phylum Echinodermata
• Spiny exterior
• Calcified internal skeleton
• Bilateral symmetry in larvae, but often
radial symmetry in adults
• Water vascular system for mobility, gas
exchange, and feeding.
– system of internal tubes and canals
– tube feet that can exert strong suction
Phylum Chordata
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Pharyngeal slits (gill slits in neck)
Ventral heart
Post-anal tail
Hollow dorsal nerve cord
Dorsal supporting rod, the notochord
– A solid rod of tissue, NOT equivalent to backbone
Many of these may become obscure, modified, or
absent in later development of the organism.
Invertebrate Chordates
No vertebral column (i.e. no true backbone)
• Tunicates (subphylum Urochordata) – tadpole-like
larva has chordate features; adults are sessile
• Lancelets (subphylum Cephalochordata –
fish-like; notochord throughout life
Vertebrates
(Subphylum Vertebrata)
• Notochord disappears, and is replaced by
vertebral column (articulated bones)
• two pairs of appendages
• anterior skull
• well-developed circulatory system
– closed system (blood leaves heart and returns to
heart in closed vessels; never pumped into open
body cavity)
Jawless fishes
Class Agnatha
Hagfish
Lampreys
Class Chondrichthyes
Cartilaginous fishes
Sharks, Rays, and Skates
Bony fishes: Class Osteichthyes
(includes ray-finned fish, lobe-finned fish,
and lungfish)
The Coelecanth, a lobe-finned fish
Amphibia
Moist skin
Eggs laid in water; External fertilization
Aquatic larvae with gills metamorphose
into air-breathing adults
Amniote Egg
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Allows fully terrestrial life.
Waterproof shell.
Reservoir of water inside the egg.
Fertilization is internal, before the shell forms.
(Later, some amniote animals evolved the ability to
retain the egg internally, never developing a shell, and
giving birth to live young.)
• Other features of Amniote animals:
– Waterproof skin
– Ability to excrete concentrated urine, in order to conserve
water.