BIO2231 Lecture Notes - Lecture 21: Gastrovascular Cavity, Circulatory System, Eumetazoa

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25 May 2018
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Lecture 21 Life on Earth Overview
The Four F-Words
Form
o What does animal look like - structure
o Fossil records
Function
o Relates to morphology
Fossils
o Allows us to date evolution of morphology
o Told us how animals formed
Phylogeny
o Use genomic differences to tell us evolution of phylogeny
Extinct Groups and Ancestors
Fossils used to date branching
Fossils are models for ancestral characters
Actual common ancestor seldom found
Small groups
Short period
Diversity now vs then
Key Evolution Transitions
Metazoa
Eumetazoa
Bilateria
Deuterostome vs. protosome
Lophotrochozoa Ecdyzosoa
Common Themes
Body plans, symmetry, body cavities, characteristic functions
Cell aggregates, diplo-triploblastic body plan
Radial vs. Bilateral
Gastrovascular cavity, coelom, Hemocoel (circulatory)
Phylum-specific morphologies:
o Cnydocytes cnidarians
o Branched gut without anus Platyhelminthes
o Water vascular system echinoderms
o Mantle cavity molluscs
Cephalization
o Evolutionary process by which sensory organs and specialised
appendages become localised to the head of animals
o Associated with orientated movement
Metamerism
o Segmentation
o Division of body into serially repeated parts (segments)
Tagmatization
o Organisastino of the arthropod body into tagmata
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