Nematodes + ecdysozoa

Question 1

What defines Ecdysozoa?

Answer 1

Animals that moult a chitinous cuticle during growth (ecdysis), regulated by ecdysteroid hormones.

Question 2

What is a shared structural feature of Ecdysozoa?

Answer 2

A cuticle containing alpha-chitin, composed of epicuticle, exocuticle, and endocuticle.

Question 3

What differentiates Ecdysozoa from Lophotrochozoa among former Aschelminthes?

Answer 3

Ecdysozoans moult their cuticle; Lophotrochozoans do not.

Question 4

What is the defining feature of Nematoda?

Answer 4

Paired lateral sensory organs called amphids on the head.

Question 5

What is eutely in nematodes?

Answer 5

A fixed number of somatic cells per individual (e.g., C. elegans has 959).

Question 6

What body shape do nematodes have?

Answer 6

Cylindrical, tapered at both ends, round in cross-section.

Question 7

How many times do nematodes moult their cuticle?

Answer 7

Four times between juvenile and adult stages.

Question 8

What does the nematode cuticle provide?

Answer 8

Hydrostatic pressure maintenance, mechanical protection, and host digestion resistance in parasites.

Question 9

Can nematodes grow after the final moult?

Answer 9

Yes, by enlarging individual cells.

Question 10

What type of muscles do nematodes have?

Answer 10

Only longitudinal muscles in four bands.

Question 11

How do nematodes move?

Answer 11

Sinusoidal thrashing via alternate contraction of longitudinal muscles.

Question 12

What kind of digestive system do nematodes have?

Answer 12

Complete tract with mouth, pharynx, intestine, and anus.

Question 13

What helps move food through the nematode gut?

Answer 13

Triradiate pharynx pumping and hydrostatic pressure.

Question 14

What major systems are absent in nematodes?

Answer 14

Circulatory, respiratory, and excretory systems.

Question 15

How are wastes removed?

Answer 15

Diffusion, gut, and possibly via renette cells.

Question 16

What is the primary sensory structure in nematodes?

Answer 16

Amphids (anterior) and sometimes phasmids (posterior).

Question 17

Describe the nematode nervous system.

Answer 17

Anterior nerve ring with dorsal and ventral nerve cords.

Question 18

Are nematodes dioecious or hermaphroditic?

Answer 18

Dioecious (separate sexes); males usually smaller.

Question 19

What reproductive structure is unique to males?

Answer 19

Spicules for holding open the female reproductive tract during copulation.

Question 20

What type of development do nematodes undergo?

Answer 20

Direct development

Question 21

Why is C. elegans a model organism?

Answer 21

Fully mapped genome and neural network, rapid life cycle, known cell lineage.

Question 22

How long is the generation time of C. elegans?

Answer 22

~3 days at room temperature.

Question 23

Name four major parasitic nematodes.

Answer 23

Enterobius vermicularis (pinworm), Trichinella, Ascaris, Wuchereria bancrofti.

Question 24

What disease is caused by Wuchereria bancrofti?

Answer 24

Elephantiasis (lymphatic filariasis).

Question 25

What’s the life cycle of W. bancrofti?

Answer 25

Mosquito transmits L3 larvae → lymph nodes → mature → produce microfilariae → circulate in blood → taken up by new mosquito.

Question 26

What do Onychophorans use to subdue prey?

Answer 26

Proteinaceous glue ejected from slime glands.

Question 27

What are lobopods?

Answer 27

Unjointed walking legs ending in claws.

Question 28

What is cryptobiosis?

Answer 28

A state of suspended metabolism allowing survival in extreme conditions.

Question 29

What type of body covering do tardigrades have?

Answer 29

A chitinous cuticle that is moulted.

Question 30

How many clawed limbs do tardigrades have?

Answer 30

Four pairs.

Question 31

Where are Kinorhynchs found?

Answer 31

Marine mud, with bodies <1 mm and covered in spines.

Question 32

What is the diet of Priapulids?

Answer 32

Predatory or detritivorous, depending on size.

Question 33

Where are Priapulids found?

Answer 33

Marine habitats from intertidal to deep sea.

Question 34

What does "Gastrotrich" mean?

Answer 34

“Stomach hair” — refers to ventral cilia.

Question 35

Where do gastrotichs live and what do they eat?

Answer 35

Interstitial FW/marine; detritus, bacteria, protozoa.

Question 36

What is notable about Loricifera?

Answer 36

Only discovered in 1983, tiny interstitial marine animals with 100+ species.

Question 37

What is unique about adult Nematomorphs?

Answer 37

Nonfunctional gut, long threadlike body, and no respiratory or circulatory system.

Question 38

What host manipulation do Nematomorphs perform?

Answer 38

Cause infected insects (e.g., crickets) to jump into water so adults can emerge.