Evolution of Animals Flashcards
What are nine characteristics of animals?
They are eukaryotes, they are multicellular, and they are heterotrophs (with a few exceptions).
They also breathe oxygen, can move, can reproduce sexually, and have cells organized into tissues.
They also develop through the blastula stage, and don’t have cell walls.
What proteins are involved in the multicellularity of animals?
Cadherins are proteins that are involved in cell to cell attachment.
What differs animal cadherins from choanoflagellate cadherins?
Animal cadherins have a reserved region called the cytoplasmic cadherin domain (CCD)
What are the two notable cell types in sponges?
Choanocytes resemble choanoflagellates and filter feed, and amoebocytes transport nutrients to other cells and can differentiate into any other cell.
Do sponges have true tissues?
No, they are not connected or separated by membranes. They also don’t have neurons.
What is characteristic of the group Eumetazoa?
They have neurons.
What part of the life cycle is dominant in animals?
The diploid phase of the diplontic life cycle.
What are three examples of an animal being able to reproduce asexually?
Budding in jellyfish, fragmentation in sponges and flatworms, and parthenogenesis in zebra sharks.
What type of cell allows for fragmentation to happen in flatworms?
Neoblasts are undifferentiated stem cells that can regenerate an entire organism.
What is parthenogenesis?
It is the ability for a female to produce offspring from unfertilized eggs.
What is radial symmetry?
It is symmetry around a central axis with no anterior or posterior regions. (ie. sea anemone)
What is bilateral symmetry?
It is symmetry across the midsagittal plane, there is a dorsal and ventral region, as well as a posterior and anterior region.
What are hox genes?
They play an important role in embryo development. They control the expression of more than 100 other genes.
What type of genes are hox genes?
They are homeotic genes which are regulatory genes that control the organization of body parts.
Define larva
A sexually immature form of an animal that is morphologically different from an adult (usually eats different food and lives in a different habitat).
