Lecture 5- Animal Diversity I Flashcards
What do we get from gastrulation?
A germ layer and the archenteron- the early digestive system
SEQ early embryonic development
- Start with diploid zygote
- Through cleavage, enter the eight-cell stage (zygote is mitotically dividing without growth)
- From eight cell-stage, cleavage again and blastulation to form blastula. Blastula is a hollow ball of cells around blastocoel (blastocoel does not become anything).
- Process of gastrulation (inward folding of blastula) is the last step. Gastrula and germ layers are formed as a result.
What is the archenteron/where is it?
The archenteron is the tube that forms as the blastula folds inward during gastrulation.
What is the name of the bottom of the tube of the gastrula/the entry into the digestive system?
Blastopore
Where is the ectoderm?
Outside of gastrula
Where is the endoderm?
Inside of gastrula
Homeobox genes
Code for proteins that regulate expression of developmental genes, homologous in all animals
Animal Characteristics
- Heterotrophic
- Multicellular
- Extracellular matrix
- Specialized cells/tissues/organs
- Diploid-dominant
- Specific, unique development pattern
Describe symmetry vs. asymmetry in body plan of animal
Symmetry- Arrangement of body structure in relation to axis of body
Asymmetry: No plane of symmetry through body
Radial Symmetry
Any plane through longitudinal axis (sea anemone)
Bilateral Symmetry
Only 1 plane through longitudinal axis (halves)- like a lobster, most animals have this
Cephalization
Development of a head + clustering of sense organs- central nervous system and sense organs, facilitates complex movement
Bilateral Animal Axes
Dorsal/Ventral (dorsal fin= goat’s back, ventral= belly
Anterior/Posterial- front and back (goat’s front includes head, neck etc and goat’s back includes butt)
Germ Layers + when are they formed?
Concentric layers of embryonic tissue, formed during the gastrulation process of embryonic development
What are the types of germ layers (3 layers)
Ectoderm- outer layer, nervous system
Endoderm- inner layer, lines digestive tube and other organs (lungs)
Mesoderm- middle layer, everything else- muscles, skeleton, etc
Diploblasts (how many germ layers?)
Two germ layers- Endoderm and ectoderm
Triploblasts (how many germ layers?)
Three germ layers- Endoderm, ectoderm and mesoderm
Do diploblasts have body cavities?
No, only triploblasts have body cavities
What is the general term for body cavity?
Coelom- fluid-filled space between body wall and digestive tube
Name the three types of coelom morphology
- True Coelomate/Eucoelomate
- Pseudocoelomate
- Acoelomate
Structure of True Coelomate/Eucoelomate
Has ectoderm and endoderm (both outer endoderm and endoderm surrounding digestive tube)
Structure of Pseudocoelomate
Has ectoderm and only one layer of endoderm (only outer endoderm, no endoderm surrounding digestive tube)
Structure of Aceolomate
No coelom, everything is mushed together and there is no fluid-filled body cavity between gut and body wall
Explain Coelom Evolutionary history
True coelom ancestral to pseudocoelom and acoelom. Pseudocoelom and acoelom are derived traits.
