BIO2231 Lecture Notes - Lecture 21: Gastrovascular Cavity, Circulatory System, Eumetazoa
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
find more resources at oneclass.com
find more resources at oneclass.com