Phylum Chordata. Deuterostomes The four traits ALWAYS –Notochord –Pharyngeal slits/pouches...
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Transcript of Phylum Chordata. Deuterostomes The four traits ALWAYS –Notochord –Pharyngeal slits/pouches...
Phylum Chordata
Phylum Chordata
• Deuterostomes• The four traits ALWAYS
– Notochord– Pharyngeal slits/pouches– Hollow, dorsal nerve cord– Postanal tail
• Other traits– Endostyle or thyroid gland– Segmental musculature
It’s What All the Chordates are Wearing
It’s What All the Chordates are Wearing
Stages & Events of Chordate EmbryogenesisDevelopmental Process Embryonic Stage
Fetus
NeurulationNeurulation
Zygote
Morula
Blastula
Gastrula
Neurula
Pharyngula
Cleavage Generates a Blastula
Gastrulation & Neurulation
Fates of Embryonic Germ Layers
Gastrulation & Neurulation
Notochord
• Embryonic mesodermal structure
• Induces neural tube formation• Serves as a dorsal support
structure
Notochord & Formation of Neural Tube
N
N
NTNT
NTNT
Pharyngula Staged Vertebrate Embryos
Chordate Cladistics
Phylogenetic Relationship between Echinoderms, Hemichordates & Chordates
Chordate Phylogeny
Phylum Chordata, Subphylum Urochordata
• Protochordates– SP Urochordata
• Notochord only in tail• Tadpole-like larvae
– Class Ascidiacea– Class Thaliacea– Class Larvacea
Ascidian
Thaliacian
Larvacian
Urochordate Larvae
Ascidian Larvae & Metamorphosis
Ascidian Adult Anatomy
Solitary AscidiansClavelina puertosecensis
Compound Tunicate Colony
Class Thaliacea (Salps)
Class Larvacea
The Ancestral Chordate
?
Phylum Chordata Subphylum Cephalochordata
• Maintain chordate structures throughout life
• Segmental myomeres very apparent
• Notochord extends entire length of body
Amphioxus Maintains All Chordate Characters• Notochord• Dorsal neural tube• Pharyngeal slits/pouches originate from neural crest
– Analogous to gill slits, inner ear & larynx• Postanal tail
– Extension of body muscle beyond anal opening
tail
Amphioxus
Pikaia• Earliest known fossil chordate• Burgess shale of BC• Obvious similarity to
cephalochordates