L12 Nematodes

Question 1

What are the general features?

Answer 1

Pseudocelomates 
Cuticle made of collagen 
Undergo 4 moults from larval stage to adult
Body wall made of epidermal syncytium
Only longitudinal muscles so move by undulation
Tapered
Dioecious
Mouth with teeth/stylet

Question 2

Why are nematodes so successful?

Answer 2

Cuticle
cross layers of linkages
makes them tough and flexible so can thrive in most environments

Question 3

How does reproduction take place in nematodes?

Answer 3

Dioecious, have a vulva for internal fertilisation, Males have spicule present to keep vagina open.
Sperm have no flagella, so crawl, couldn’t swim as inside of body under high pressure

Question 4

What determines sex in nematodes?

Answer 4

Environmental sex determination - Depends on the stress in the environment, lots of resources means become female

Question 5

Describe caenorhabditis elegans

Answer 5

Freeliving, hermaphrodite, only has a set 100 cells in the body. Used in medical research as easy to track cell fates,

Question 6

Talk about are parasitic nematodes?

Answer 6

Evolved several times within the nematodes 
Radiation with coevolution of hosts
Can have intermediate hosts
Can reach up to 9m long
Children are very susceptible 
Can migrate around the body

Question 7

What is the root knot nematode?

Answer 7

Affects plants, feeds on the roots, disrupting the ability to absorb nutrients. Leads to crop distortion and lower yields

Question 8

What does skrjabinocleva morrisoni do?

Answer 8

Able to manipulate host behaviour, intermediate host is an amphipod, makes them stay close to water surface in the day so more likely to be predated by a bird, the final host

Question 9

What does the myrmeconema neotropicum do?

Answer 9

Ants are the intermediate host, makes abdomen turn red, so that are more attractive to bits, and when eaten, the nematode can pass to the definitive host

Question 10

What is the lifecycle of the enberobius, pin worm?

Answer 10

Lives in human gut, no intermediate host. Enters host by injection, foes into lungs, and makes its way to the gut through the blood stream. Eggs are coughed up, and swallowed back down to hatch again

Question 11

How does a (Dracunculus) guinea worm pass its eggs to another host?

Answer 11

Adult forms an ulcer in the skin, pain is relieved by water, which washes out eggs. Contact with contaminated water by another individual then lead to infection

Question 12

What are (Wuchereria) filariods?

Answer 12

Adults inhabit the lymphatic system of host, block them up, causing excess tissue fluid to build up. Can lead to elephantiasis. Mosquitos are the intermediate host