Body Plans Flashcards
Body plan
Structural characteristics of an organism that separates it from other organisms or groups of organisms
Symmetry
The quality of being made up of exact similar parts facing each other
Cephalization
When Most of the sense organs , feeding appendages and the brain are near the anterior part of the body
Coelom
Internal fluid filled cavity that develops in the mesoderm of triploblastic animals and separates digestive tract from body
Asymmetry
No symmetry
E.g sponge
Radial symmetry
Can be cut in more than one vertical plane through centre
Bilateral symmetry
Can only be cut in one vertical plane
Germ layers
Group of cells in an embryo that interact with each other as the embryo develops and contribute to the formation of all organs and tissues
Ectoderm
Outer germ layer
Endoderm
Inner germ layer
Mesoderm
Germ layer between ectoderm and endoderm
Diploblastic
2 germ layers ( radial symmetry )
Triploblastic
3 germ layers (bilateral symmetry)
Acoelomate
Has no cavity in mesoderm
Eg flat worm
Pseudocoelomate
Has a coelom but is not seen as a ‘true’ coelom because it is not surrounded by mesoderm tissue
