Intro to Nematodes

Question 1

these are also called roundworms

Answer 1

nematodes
phylum = Nematoda

Question 2

the most abundant animals on earth

Answer 2

Nematoda

Question 3

how do nematodes exist?

Answer 3

free-living forms or as parasites (animals/plants)

Question 4

general features of nematodes

Answer 4

• elongated, cylindrical, smooth, unsegmented flesh-coloured bodies
• body tapered to a pointed posterior end , and to a rounded anterior end
• body covered by a noncellular highly resistant coating = “cuticle”
• complete digestive system with mouth, oesophagus, midgut, and anus
• all are separate sexes
  > female = larger usually
• 2 main categories according to primary location
  > intestinal nematodes
  > tissue nematodes (filariae)

Question 5

possibly most diverse species on earth

Answer 5

nematodes

trailing behind only the anthropods

Question 6

T or F. Only small percentage of nematodes are parasitic

Answer 6

T

Question 7

a tube within a tube

Answer 7

nematode

Question 8

size of nematodes

Answer 8

<1mm to 1 m

Question 9

epidermis of nematodes

Answer 9

a mass of cellular material and nuclei without separte membranes

Question 10

thick outer cuticle of nematodes

Answer 10

both tough and flexible, shed and re-secreted 4 times during development from juvenile to mature adult

Question 11

the closest thing a roundworm has to a skeleton

Answer 11

cuticle (secreted by epidermis; not made up of cells)
- worm uses its cuticle for support and leverage pt for movement

Question 12

what is underneath the cuticle of nematode?

Answer 12

hypodermis and body cavity of nematode = pseudocoel fluid (sometimes not present) = medium of circulation

Question 13

underneath epidermis of nematodes =

Answer 13

longitudinal somatic muscles = can only bend body from side to side; cant crawl or lift itself

aimlessly thrashing around

Question 14

digestive system of nematode

Answer 14

mouth (head of nematode) has spines, hooks, cutting plates = designed to help nematode latch onto body of host

muscular pharynx extending into gut

anus

nutrients and waste distributed through body cavity = contents regulated by longitudinal excretory canal along each side of the body

Question 15

nervous system of nematode

Answer 15

two longitudinal nerves on both dorsal (back) and ventral (belly) side

NOTE: muscle cells branch toward the nerves not the other way around

both nerves connect to a nerve ring located near head

Question 16

T or F. In nematodes, no vascular system or respiratory system exists for uptake/distribution of oxygen

Answer 16

T!

Question 17

SOME NEMATODES CAN MULTIPLY BY ______________

Answer 17

parthogenesis

Question 18

very few egg output daily

Answer 18

Strongyloides

Question 19

200 000 egg output daily

Answer 19

Ascaris

Question 20

ovoviviparous

Answer 20

Trichinella
= internal fertilization; young born alive; no pacental connection

Question 21

5 successive stages of nematodes

Answer 21

4 larval
1 adult

Question 22

what is the infective stage of the nematode?

Answer 22

usually 3rd laval stage

Question 23

cycle within one host

Answer 23

Ascaris\

Question 24

this nematode can live freely if no host

Answer 24

filariae