What is the development of animals in order?
- Zygote
- Multiplies many times and creates “Eight cell stage” and Cleavage is formed (spiral cleavage in protostomes and radial in deuterostomes)
- Blastula (hollow inside surrounded by cells)
- Gastrulation occurs and starts to create a hole in the middle.
- Blastopore is formed = hole in the blastula
How is a protostome developed?
- Blastopore becomes the mouth of the organism
- Cleavage in the eight cell stage is not aligned (spiral)
- determinate (already know what tissue to make)
How is a Deuterostome developed?
- Blastopore becomes the Anus
- Cleavage in the eight cell stage is aligned (radial)
- indeterminate
What are the 3 different germ layers?
Ectoderm, Mesoderm, Endoderm
What are the functions of each of the 3 germ layers?
Ectoderm: the germ layer covering the surface of the embryo, gives rise to the outer covering of the animal and to some phyla the central nervous system.
Mesoderm: fills the space between the ectoderm and endoderm.
Endoderm: the innermost germ layer, lines the pouch that forms during gastrulation and gives rise to the lining of the digestive tract.
What is an Eucoelomate?
A Eucoelomate are animals that have a true coelom, a body cavity completely lined by tissue derived from mesoderm. (earth worms, annelids etc.)
What is a Pseudocoelomate?
A Pseudocoelomate are animals that have a body cavity lined by tissue derived from mesoderm and by tissue derived from endoderm. Seems like it has a true coelom but have part of its cavity covered by mesoderm. (Roundworms)
What is an Acoelomate?
No cavities (platyhelminthese)
