Phylum Nematoda Flashcards
0
Q
Environment & importance
A
- live in aquatic, wet soils, or moist tissues if plants & animals
- important decomposers
- live everywhere on earth (incl. extreme environments like ice & hot springs)
- live in/on almost every plant & animal alive
1
Q
Nematode physical characteristics
A
- pseudocolomates
- eumetizoa
- non-segmented
- parasitic & free living types
- transparent
- periodically shed exoskeleton (cuticle)
- cuticle made of collagen
2
Q
Pseudocolomates
A
- “false” body cavity: space between mesoderm & endoderm layers
- has gut & reproductive organs in it
- filled with fluid
- high pressure gives worm it’s shape
3
Q
Movement
A
- longitudinal muscles only
- muscles activated by dorsal & ventral nerves
- muscle cells branch toward the nerves (unlike every other animal)
- can’t crawl or lift itself
4
Q
Respiration
A
Diffusion
5
Q
Feeding
A
- mouth opens into pharynx that pulls in & crushes food
- long simple gut cavity w/o muscles (complete gut)
- anus near tip of body
- food isn’t distributed by a specialized system
- quick digestion
- poop expelled under pressure
- can be either herbivores, bacterivores, fungivores, predators, or omnivores (specialized due to special mouthparts)
6
Q
Herbivores
A
- needle-like “stylet” mouthparts to puncture during feeding
- can be ectoparasites (remain in soil at roots surface) or endoparasites (live & feed inside root)
7
Q
Bacterivores
A
- free living
- mouth is called stoma, and is just a hollow tube
- decomposers
8
Q
Fungivores
A
- use stylet to puncture fungi
- decomposers
9
Q
Predators
A
- feed on other nematodes (either parasitic or free-living) & animals
10
Q
Omnivores
A
- most nematodes are NOT omnivores
11
Q
Reproduction
A
- not hermaphroditic
- reproduce often
- reproductive organs fill most of their body
- internal fertilization
- larvae go thru 4 moults
12
Q
Internal circulation
A
- diffusion
- no blood/circulatory system
13
Q
Excretion
A
- waste distributed to body cavity
- regulated by excretory canal
- renette cells used
14
Q
Renette cells
A
Specialized cells acting as excretory glands
15
Q
Response to environment
A
- dorsal & ventral nerves
- ventral nerve has series of nerve centres connecting to a nerve ring
- head has more nerve centres/sense organs
16
Q
Disease
A
- trichinosis (in muscles)
- pinworms (crawl out of anus at night & transferred by scratching itchy bum)
- elephantitis (block passage of fluid within lymph vessels)
- guinea worm disease (eat through skin, creating holes in you)
- river blindness
17
Q
Examples of Nematodes
A
- hookworm
- whipworm
- heartworm
- roundworm
- ascaris
