Introduction To Animals And Non Bilaterians Flashcards
What are Choanoflagellates
A unicellular sister group to animals (protists)
What is the group metazoa
Metazoa = animals
What ambiguities remain when looking at the evolutionary history of animals
Early branching taxa are the most ambiguous, we don’t know if sponges or placozoans came first
What does diploblast mean
2 germ layers and radial symmetry
What is meant by bilateria
3 germ layers and bilateral symmetry
Why was the development of a mesoderm layer in bilaterians important
It allowed for the development of specialised internal structures and organs
What is the morula
A compact cluster of cells formed after the zygote has started to decide
What is the blastula
A hollow ball of cells with an inner cavity (blastocoel) formed during early embryonic development
What happens during gastrulation
Cells migrate through the blastopore into the blastocoel forming either 2 (non bilateria) or 3 (bilateria) germ layers: the ectoderm, mesoderm and endoderm
How are protostomes and deuterostomes seperated
In deuterostomes the blastopore becomes the anus
In protostomes the blastopore becomes the mouth
What is meant by organogenesis
The formation of organs
What are hox genes
Highly conserved genes that control positional identity within an animals body plan
What groups are in the non bilaterians
Ctenophores
Placazoans
Porifera
Cnidaria
What is the phylogeny of ctenophores
Fully marine
250 species
Earliest group to split from other animals
What is the body plan of ctenophores
Diploblastic (2 germ layers)
Complete gut
Hermaphroditic
Uncentralised nervous system
