Chapter 32: Overview of Animal Diversity Flashcards
Definition of animal?
- Multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layers
Nutritional mode of plants
Autotrophs
Nutritional mode of fungi
Absorb nutrients from their surroundings; grow on their food and feed by absorption
Nutritional mode of animals
Heterotrophs; ingest nutrients and use enzymes to digest within bodies
Tissues
Groups of similar cells that act as functional unit
Development Stages
- Zygote (unicellular) forms from sperm + egg
- Eight-cell embryo is formed by 3 rounds of cell division
- Cleavage produces a blastula (cavity)
- Undergoes gastrulation
- Pouch formed creates an external ectoderm, endoderm (develops into tissue lining the animal’s digestive tract)
What’s special about animal cells?
- Ability to move and conduct nerve impulses underlie many of adaptations that differentiate animals from plants
Cleavage
Succession of mitotic division without cell growth between the divisions
Gastrulation
Layers of embryonic tissues that will develop into adult body parts are produced
Metamorphosis
Developmental transformation that turns animal into a juvenile that resembles adult but is not sexually mature
Significance of choanoflagellates in animal development?
- ## Choanoflagellates marked the transition from uni-cellularity to multicellularity
History of animals spans how many years?
More than 700 billion
Paleozoic Era
- 542-251 MYA
- Included Cambrian explosion
- Many major groups of animals appeared at this time
- Hypothesized to have occurred as a result of more oxygen, increased intensity of predation, and evolution of new developmental genes
Mesozoic Era
- 251-65.5 MYA
- Animal phyla begins to spread
- Coral reefs emerged
- Dinosaurs were dominant
- Flowering plants/insects diversified
Cenozoic Era
- 65.5 MYA to present
- Mass extinctions of both terrestrial and marine animals
- Begin diversification of mammals
Neoprotozoic Era
- 1 billion-542 MYA
- Earliest members of the fossil record were “Edicaran biota”
Radial symmetry
- Type of symmetry found in a flower pot
- Slice through central axis to divide animal into mirror images
Bilateral symmetry
- Two axes of orientation: front to back and top to bottom
- Such as a shovel
- Have dorsal (top), ventral (bottom), left/right, posterior (back) and anterior (front)
Ectoderm
- Germ layer covering surface of embryo gives rise to the outer covering of the animal
- In some phyla to the central nervous system
Endoderm
- Innermost germ layers; lines pouch that forms during gastrulation and gives rise to lining of digestive tract and organs
Diploblastic
- Two germ layers (cnidarians and few other animal groups)
Triploblastic
- All bilaterally symmetrical
- Have mesoderm
Cephalization
Concentration of nerve organs during embryonic development
Protostome Development
- Spiral, determinate eight cell stage (planes of cell division are diagonal to vertical axis of embryo)
- Solid mass of mesoderm split and form coelom
- Mouth develops from blastopore
Deuterostome development
- Radial and indeterminate eight cell stage
- Folds of archenteron form coelom
- Anus develops from blastopore
Blastopore
Indentation that during gastrulation leads to formation of archenteron
Diversification of Animals
1) All animals share common ancestor
2) Sponges are basal animals
3) Eumetazoa is clade of animals with true tissues
4) Most animal phyla belong to clade Bilateral
5) Three major clades of bilateral (Deutorosomia, Lophotrochozoa, and Ecdysozoa)
