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
What are organisms that float freely called?
They are referred to as planktonic
What does ’planktonic’ refer to?
Organisms that float freely or weakly swim For example jellyfish
What are organisms that can move called?
Motile
What does ’motile’ refer to?
Organisms that can move i.e. mammals
What are the basic layers of tissue called?
‘Germ layers’
What does ’germ layers’ refer to?
The basic layers of tissue i.e. mesoderm, ectoderm
What are the basic germ layers?
Endoderm and ectoderm
Most animals also have mesoderm
How are organisms grouped based on germ layers?
As diploblastic or as triploblastic
What are diploblastic organisms?
Those that have only two germ layers (ectoderm and endoderm)
What are triploblastic organisms?
Those that have three germ layers (ectoderm, endoderm and mesoderm)
What are organisms that have two germ layers called?
Diploblastic
What are organisms that have three germ layers called?
Triploblastic
What organisms are diploblastic and what are triploblastic?
Diploblasts include cnidarians i.e. jellies and corals.
All bilaterally symmetrical organisms are triploblastic.
Sponges are neither: they lack true tissues
Are sponges diploblastic or triploblastic?
Neither as they lack true tissues
Are jellyfish diploblastic or triploblastic?
Diploblastic
Are coral diploblastic or triploblastic?
Diploblastic
Are insects diploblastic or triploblastic?
Triploblastic
Are humans diploblastic or triploblastic?
Triploblastic
Are flatworms diploblastic or triploblastic?
Triploblastic
What is a body cavity?
A fluid or air filled space located between the digestive tract and outer body wall.
What is a grade?
A group whose members share key biological features
How does a grade differ from a clade?
Organisms that have similar features due to analogy are still considered to be part of the same grade even if they are only distantly related
How are organisms grouped based on their body cavities?
As coelomates, pseudocoelomates or as a coelomates
What is a body cavity also called?
A ‘coelom’
What does ’coelom’ refer to?
A body cavity i.e. fluid or air filled space located between the digestive tract and outer body wall.
What are ‘coelomates’?
Organisms that have a true coelom
What are ‘pseudocoelomates’?
Organisms with pseudocoelom
What are are a coelomates?
Organisms that have no coelom or psueodcoelom
What is the difference between a coelom and a pseudocoelom?
A true coelom is completely surrounded by mesoderm tissue.
In a pseudocoelom there are a set of concentric rings with a layer of mesoderm and a cavity with a digestive tract composed of endoderm in the centre.
Note that in a pseudocoelom the cavity touches the endoderm and hence it is not a true coelom
What is an example of a coelomate?
An earthworm
What is an example of a pseudocoelomate?
A roundworm
What is an example of an acoelomate?
A planarian
Based on its body cavity, what is an earthworm?
Coelomate
Based on its body cavity, what is a roundworm?
Pseudocoelomate
Based on its body cavity, what is an planarian?
Acoelomate
How are organisms grouped based on development?
As protostomes or as deuterostomes
What are protostomes?
Organisms in which the mouth develops from the blastopore and thus appears before the anus
What are deuterostomes?
Organisms in which the mouth develops from the blastopore and thus appears before the mouth
What are animals in which the anus develops first called?
Deuterostomes
What are animals in which the mouth develops first called?
Protostomes
What are some examples of protostomes?
Molluscs and annelids
What are some examples of deuterostomes?
Echinoderms and chordates
Are molluscs protostomes or deuterostomes?
Protostomes
Are annelids protostomes or deuterostomes?
Protostomes
Are echinoderms protostomes or deuterostomes?
Deuterostomes
Are molluscs chordates or deuterostomes?
Deuterostomes
Are molluscs humans or deuterostomes?
Deuterostomes
Are sea urchins humans or deuterostomes?
Protostomes
What are the basic ways protostomes and deuterostomes differ?
Cleavage, coelom formation and fate of the blastopore.
How do protostomes and deuterostomes differ in terms of cleavage?
In general, protostome development begins with spiral, determinate cleavage.
Deuterostome development is characterized by radial, indeterminate cleavage.
How do protostomes and deuterostomes differ in terms of coelom formation?
Coelom formation begins in the gastrula stage.
In protostome development, the coelom forms from splits in the mesoderm.
In deuterostome development, the coelom forms from mesodermal outpocketings of the archenteron.
How do protostomes and deuterostomes differ in terms of the fate of the blastopore?
In protostome development, the mouth forms from the blastopore.
In deuterostome development, the mouth forms from a secondary opening with the blastopore becoming the anus.
What is determinate cleavage?
The fate of each cell is determined early in develop. Thus if a single cell is isolated it can not develop into a full organism
What is indeterminate cleavage?
Each cell produced by early cleavage divisions retains the capacity to develop into a complete embryo.
For example, if the cells of a sea urchin embryo are separated at the four-cell stage, each can form a complete larva.
Do humans perform determinate or indeterminate cleavage? What is the consequence of this?
Indeterminate cleavage.
This means that when an embryo splits into two each can form an individual in the case of identical twins
What concept allows identical twins?
Indeterminate cleavage as the embryo can split into two with each becoming a full organism.
