The Ecdysozoa Flashcards
1
Q
The Ecydysozoa are nested within the
A
Bilateria
2
Q
Give the Ecdysozoan Classes
A
- Nematodes
- Nematomorphs
- Tardigrades
- Onychophora
- Arthropods
- Priapulids,
- Kinorhynchs
- Loriciferans
3
Q
Which are the ‘wormy’ Ecdysozoan Classes
A
- Nematodes
- Nematomorphs
4
Q
What are the ‘leggy’ Ecdysozoan Classes
A
- Tardigrades
- Onychophora
- Arthropods
5
Q
What do the Ecdysozoa have in common?
A
cuticle moulted as animal grows
6
Q
Describe the Ecdysozoa
A
- stiff (rigid or bendy) cuticle evolved early on this branch
- moulting allows growth despite cuticle that can’t stretch much
7
Q
Describe the evolutionary constraints of a stiff cuticle
A
problems for locomotion
8
Q
Describe the Nematoda
A
- roundworms
- stiff cuticle: not stretchy
- cuticle, epidermis, body-wall muscles, pharynx muscles, ventral nerve cord, lateral cord, gonodcuct, oocyte,
- no segmentation
- coelom with very high liquid pressure
- helical collagen fibres in cuticle
- can’t expand/contract body regions
- characteristic thrashing motion
- e.g. “Vinegar eels”- coelom with very high liquid pressure
- helical collagen fibres in cuticle
9
Q
Describe Vinegar eels
A
- Turbatrix aceti
- live in vinegar, gone-off cider etc
10
Q
Explain the thrashing motion of nematodes
A
- only L, not C muscle
- stiffness allows both sides to antagonise one another
- coelom forms semi-rigid, liquid skeleton
- gives ‘round’ shape
11
Q
How do Nematoda manage their through-gut?
A
- muscles at anus control open/close
- muscular, triradiate pharynx (sometimes called stoma) at mouth
- pumps food in, up to 4 pulse/second
12
Q
Give an example of the Nematoda
A
- Enoplus
- 3 teeth
- 6 inner labia papillae
- 10 cephalic setae
- viewed under SEM
13
Q
Describe Nematoda springiness
A
- specialised cuticle
- several layers
- helical collagen fibres compress and bend: extend the muscles
- permeable to water and gases
- moulted x4
14
Q
Describe the Nematode specialised cuticle from top to bottom
A
- 3 fibrous layers
- basal lamina
- epidermis
15
Q
Summarise Nematoda locomotion
A
- sinous body waves
- good through soil, fruit or body tissues
- bad swimmers