32 Overview of Animal Diversity Flashcards
What are the basic commonly agreed upon facts about animals based on phylogeny?
- All animals share a common ancestor
- Sponges are basal animals
- Eumetazoa is a clade of animals with true tissues
- Most animals belong to the clade bilateria
What are the basic features of animals?
- Multicellular
- Heterotrophs
- Eukaryotes
- Tissue that develop from embryonic layers
- Lack cell walls
In what organisms is collagen found?
Only animals
Define tissue.
A group of cells that have a common structure or function
What is the basic process of animal development?
The zygote then undergoes cleavage (mitotic cell divisions without cell growth). Cleavage leads to the formation of a multicellular stage called a blastula, which consists of a hollow ball.
Then gastrulation occurs, during which the layers of embryonic tissues that will develop into adult body parts are produced.
The resulting developmental stage is called a gastrula.
What is a larva?
A sexually immature form of an animal that is morphologically distinct from the adult.
This differs from humans where babies grow directly into adults
What is it called when larva become adults?
Metamorphosis
What is metamorphosis?
When larva become adults
What are homeoboxes?
A class of closely related sequences that appear in the regulatory genes of many animals
What are hox genes?
A class of specific homeobox genes
Do all animals have hox genes?
All do except sponges that have a different type of homeobox genes
What organism are animals most closely related to?
Choanoflagelllates (protists)
What is a ‘collar cell’
The type of cell that make up the mouth of a sponge. They contain a flagella for filter feeding
What is a ‘choanocyte’?
Aka collar cell
The type of cell that make up the mouth of a sponge. They contain a flagella for filter feeding
What does ’Ediacaran biota’ refer to?
A group of early animals that are soft-bodied multicellular eukaryotes.
What are the hypothesises for the Cambrian explosion?
- Predators acquired novel adaptions and prey acquired new defences-new predator prey relationships selected against certain groups leading to vacant niches.
- Rising oxygen levels
- Origin of Hox genes allowed greater diversity
What are fern ‘galls’?
Enlarged cavities that fern plants form in response to stimulation by resident insects
What is a common response of ferns to insects?
The formation of ‘galls’ which are enlarged cavities that fern plants form in response to stimulation by resident insects.
What is the basic shape of an animal called?
Its body plan
What is a body plan?
A particular set of morphological and developmental traits that determine the development and thus structure of an animal and
What does ’evo-devo’ refer to?
The interface between evolution and development i.e. the idea that changes to homeotic genes affect development
What are the basic forms of symmetry?
Radial and bilateral
What are the axes of organisms?
Dorsal is top, ventral is bottom.
They have a ‘left’ and a ‘right’ side
Posterior is top, anterior is the bottom
What does ’dorsal’ refer to?
The top
What does ventral refer to?
The bottom
What does posterior refer to?
Top
What does anterior refer to?
The bottom
What is the top called?
Dorsal
What is the bottom called?
Ventral
What is the bottom called?
Posterior
What is the front end called?
Anterior
What is the concentration of brains near the anterior called?
Cephalisation
What is cephalisation?
An evolutionary trend towards sensory apparatus i..e the brain begin concentrated at the anterior end of the organism
How are organisms grouped based on how they move?
Sessile, planktonic and motile
What are organism that do not move called?
Sessile
What does ’sessile’ refer to?
An organism that does not move and thus live attached to a substrate