Animal Evolution

1
Animal Evolution

• Precambrium Sea
• Multicellular
• Competition

2
Characteristics of animals

• Animals are multicellular heterotrophic
  eukaryotes
• Ingestion to make inorganic chemicals
• Animal cells lack cell walls and are held
  together by proteins (collagen)
• Nervous Tissue and Muscle Tissue
• Reproduce sexually with the diploid stage being
  dominant

3
Early Embryonic Development
Cleavage mitotic division Multiple cells combine
Blastula hollow ball of cells Hollow portion
called Blastocoel
Embyronic Layers Form. Endoderm and Ectoderm
4
Traditional Body Plans

• Major characteristics, embryonic development
• Major branches called Grade

1. Parazoa-Eumetazoa Formation of Tissues
2. Radiata-Bilateria
3. Acoelomate-Pseudocoelomate-Coelomate
4. Protostome-Deuterostome
5
Radiata-Bilateria Dichotomy

• Bilateralism forms Dorsal, Ventral, Anterior,
  Posterior

• Cephalization adaptation for movement.

• Germ Layers various layers of cells in
  development.

• Ectoderm gives rise to outer covering, CNS
• Endoderm innermost layer, digestive tube
• Mesoderm b/w other two layers, muscle and other
  organs

• Diploblastic two germ layers (radiata)
• Triploblastic Three germ layers (bilateria)

6
Protostome-Deuterostome Dichotomy
Protostome mollusks, annelida,
arthropoda Deuterostomes Echinodermata, Chordata

• Cleavage division of cells,
• Spiral Cleavage Protostomes, Early developmental
  fate,
• Radial Cleavage Deuterostomes, indeterminate
  cleavage

• Coelom Formation

Blastophore Fate Protostome blastophore forms
mouth Deuterostome blastophore forms anus