Invertebrates
Vertebrates
Phylogenetic tree
Germ layers
Ectoderm
Mesoderm
Endoderm
Coelom
Primitive
Acoelomate
Pseudocoelomate
Eucoelomate
Asymmetry
Radial symmetry
Sessile
Bilateral symmetry
Cephalization
*Phylum Porifera
Spongocoel
Spicules
Filter feeder
Monoecious
*Phylum Cnidaria
Anemone
Dioecious
Cnidocytes
Medusa
Polyp
*Phylum Platyhelminthes
*Phylum Nematoda
Protostomes
Deuterostomes
*Phylum Annelida
Closed circulatory system
Hirudin
*Phylum Arthropoda
Exoskeleton
Chitin
Open circulatory system
Head, Thorax, Abdomen
Molting
Metamorphosis
egg - nymph - adult
egg - larva - pupa - adult
Last updated on 15 August 2008