nemata Flashcards
1
Q
Introduction – Nemata (nematodes)
A
- Round worms and thread worms
- Global distribution
- Parasitic on plants and animals; or free-living
- Marine, freshwater and terrestrial
- extremely numerous and very common
2
Q
Classification
A
Kingdom: Metazoa
Phylum: Nemata
Class: Adenophora, Secernentea
3
Q
Key characteristics
5 points
A
- Bilaterally symmetrical,
- triploblastic
- Body more than two cell layers thick:
Tissues, organs, nervous system, and through-gut
No circulatory or gas exchange systems
- Unique sense organs
Amphids (anterior, open)
Phasmids (posterior, open)
Deirids (lateral, closed) - Dioecious
4
Q
Body structure
3 points
A
- Triplobastic
Ectoderm, endoderm and mesoderm - Body wall comprised of:
cuticle [very important for extremophillic organisms]
epidermis
longitudinal muscle layers
- Pseudocoelomate
[space between mesoderm and endoderm Not because of folding of mesoderm]
5
Q
Locomotion
3 points
A
- Alternate contractions of the longitudinal muscles
- Substrate contact enhanced by various structures
- Cannot burrow; no circular muscles
6
Q
Feeding
6 points
A
- Predators
- Scavengers
- Grazers
- Deposit feeders
- Symbiosis
(chemosynthetic bacteria) - Parasites
7
Q
Reproduction (sexual)
5 points
A
- Dioecious
- Sexual dimorphism [males smaller than females]
- Phermemones
[female release. Attracts male. Groove inside female which male sits in periodically release sperm to eggs] - Internal fertilisation
Direct development - Some hermaphrodites
8
Q
Class: Adenophorea
4 points
A
- Cephalic receptors - amphids
- Lack caudal receptors - phasmids
- Simple excretory system
Without collecting tubules - Mostly free-living
9
Q
Class: Secernentea
4 points
A
- Cephalic receptors - amphids
- Caudal receptors - phasmids
- Complex excretory system
Well developed collecting tubules - Mostly parasitic
