Animals - Annelida Flashcards
Segemented worms
What is the main new feature that entered with phylum Annelida?
Protostome vs deuterostome.
What is a protostome?
A type of cell developments in Annelids, arthropods, and mollusca.
Give the three defining characteristics of a protostome:
These animals cells exhibit a spiral type of cleavage. Each time, the new cells are sligtly off-centered giving the appearance of a pinecone.
The early fate of the cleavage of their cells is determinate.
The fate of their blastopore is a mouth.
What are the determining characteristics of a deuterostome?
Fate of the blastopore: anus.
The early fate of the cleavage of their cells is indeterminate.
When their cells cleave it is radial - they are not off-set in any manner (would look their they form right behind the other).
Essentially, deuterostomes cleavage and blastopore determination is the complete opposite of protostomes.
Which Phyla’s are considered deuterostomes?
Enchinodermata and Chordata.
What are 3 defining characteristics of Annelids?
1) They have bilateral symmetry.
2) They are cephalized (head).
3) And they are triploblastic -meaning they have 3 true tissue layers.
