TOPIC 23: Ecdysozoa

Question 1

what is clade ecdysozoa characterized by?

Answer 1

by molecular phylogeny

Question 2

what kind of group is clade ecdysozoa

Answer 2

monophyletic

Question 3

what are ectodysozoans protected by

Answer 3

their cuticle

Question 4

a tough, non-living outer layer of orgnaic material outside of the epidermis

Answer 4

cuticle

Question 5

functions of a cuticle

Answer 5

• protect the animal for dessication and mechanical injury
• exoskeleton for structural support

Question 6

if a cuticle is a non living outer layer, what can we infer?

Answer 6

that it does not grow, causing animals to moult

Question 7

three layers of a cuticle

Answer 7

• endocuticle
• exocuticle
• epicuticle (no cuticle)

Question 8

what is special about the epicuticle

Answer 8

its a thin, water resistant layer with not cuticle

Question 9

_____ run from the epidermis to the top of the cuticle

Answer 9

fine ducts

Question 10

how are ecdydid differ in cuticle function compared to ecdysozoa

Answer 10

they can regenerate their missing limbs

Question 11

sclerotized meaning

Answer 11

hard

Question 12

in anthropods, the cuticle is ___ in specific regions

Answer 12

sclerotized

Question 13

process that corss-links chitin polymers with protiens to create a hard and rigid cuticle

Answer 13

sclerotization

Question 14

regions where there is no sclerotization

Answer 14

unslcerotized

Question 15

what does an unslcerotized cuticle contain?

Answer 15

contains unmodified chitin that is translucent and allow for movement

Question 16

does moulting begin internally or externally?

Answer 16

internally

Question 17

steps to moulting

Answer 17

1) ecdysozoan becomes inactive
2) apolysis: separation of the epidermis from the cuticle
3) inactive enzymatic moulting fluid fills empty space
4) growth of the epidermis
5) secretion of new cuticle
6) activation of enzymes in moulting fluid
7) shedding of old cuticle
8) sclerotization of the new cuticle

Question 18

what happens to the old enzymes from the old cuticle during moulting

Answer 18

they get digested by the epidermis and is reused for the new cuticle

Question 19

characteristics of nematodes

Answer 19

• simple body plan due to secondary simplication
• lack segmentation, appendages and eyes
• no circulatory system
• moult their cuticle
• have hemocoel

Question 20

how is movement achieved om phylum nematoda

Answer 20

they move with side to side contractions of body wall muscles