lecture 13 Flashcards
1
Q
what is an animal
A
- multi-cellular, heterotrophic eukaryotes
- nutrients are obtained by ingestion
- means eating food
- contrast to absorbtion used by fungi which occurs outside of the body
- digestion occurs within the animal body
- cells lack cell walls
- lack same strength found in fungi and plants
- muscles cells used for movement
- nerve cells for conducting impulses
- unique intracellular junctions hold cells together
- most are diploid and reproduce sexually
2
Q
stages of animal reproduction cycle
A
- male ad female haploid gametes are produced by meiosis
- egg and sperm fuse producing a zygote
- the zygote divides by mitosis
- the bastula which is a hollow ball of cells is an early embryonic stage
- one side of the blastula folds inward forming a gastrula
- internal sac formed during gastrulation becomes the digestive tract lined by the endoderm
- also an ectoderm: outer cell layer tat gives rise to the outer covering of the animal and if present also the central nervous system
- third embryonic layer, the mesoderm forms the muscles and most internal organs
- after the gastrula most animals will develop into adults
- others will develop into one or more larval stages
3
Q
larval
A
- larva is an immature individual that looks different that the mature adult body form
- in order for the larva to become an adult that reproduces sexually it under goes a major change in the body form called metamorphosis
- this transformation is controlled by special gene sets
4
Q
the animal ancestor
A
- common animal ancestor thought to have lived 1 billion years ago
1. an aggregate of identical cells formed-few cells
2. larger colonies likely formed hollow spheres
3. eventually cells in the colony became specialized for certain functions such as reproduction and locomotion
4. a single multi-cellular organism likely formed from infolding of one side of the colony
5. a gastula-like-proto-animal eventually would have formed - there are no fossils to document this evolutionary process: oldest fossil is 575 million years ago
5
Q
invertebrates
A
- there are approximately 36 phyla of animals and most are invertebrates
- invertebrates: refer to animals lacking a vertebral column
- vertebrates: have a vertebral column
- all but one of the 35 phyla are invertebrates
6
Q
body plan features
A
- categorization of animals is accomplished by grouping them according to their body plans:
1. symmerty
a) radial symmetry: body parts radiate from the center - animal has a top and a bottom but not a right and left side
b) bilateral symmetry: mirror image right and left sides - a distinct head: anterior end
- a distinct tail: posterior end
- a back (dorsal surface)
- a bottom (ventral surface)
7
Q
body structure
A
- animals body structure correlates with lifestyle
- radial animals are usually sedentary, meeting their environment equally on all sides
- bilateral structured animals have all of their sense organs located within the head region ex) eyes, brain, mouth
- this arrangement facilitates mobility
8
Q
body plan structure
A
- animals that have three tissue layers can be characterized by the presence or absence of a body cavity
- this is a fluid filled space between the digestive tract and the outer body wall
- this cushions the internal organs and enables them to grow and move independently of the body wall
- soft bodied animals have a hydrostatic skeleton
- a non-compressible fluid in the body cavity of soft-bodied animals
- provides a rigid structure that muscles contract against
- a) true coelom: animals that have a body cavity lined entirely by tissue from the mesoderm ex) segmented worm
b) psuedocoelom: a body cavity lined with tissues that were not completely derived from the mesoderm tissue - these function just like true coeloms
- ex) roundworms
c) acoelomates: no body cavity
9
Q
protostomes vs deuterostomes
A
a) protostomes: the opening formed during gastrulation becomes the mouth
b) deuterostomes: the opening formed during gastrulation becomes the anus and the mouth develops from a second opening
