Phylum Nematoda Flashcards
What are the shared morphological characteristics with ecodysozoa?
- Molt a cuticle
- No motile cilia/flagella
What is a special aspect of this animal?
Eutely->once it hatches, the cells it has at that time are the cells for the rest of its life (except the germ cells)
What does the nervous system consist of?
- Anterior nerve ring
- longitudinal nerve chords
What is their outside covering?
a CUTICLE: Multilayered, fibrous and collagenous
-forms glassy covering
What type of cells is their epidermis made of?
It is synectcal (sheet of tissue with many nuclei)
Do they have a eucoelom? If not what do they have?
No eucoelom, they have a PSEUDOCOEL (mesodermal derivatives only on body wall)
What are the components nematodes use to move?
- Stiff cuticle (layers of collagen fibres) stores strain energy
- High pressure fluid in pseudocoel
- Longitudinal muscles only
Do they have circular muscles?
NO
How is that movement propagated?
-posterior to anterior down length of worm
Describe how movement works
- By alternating contractions of longitudinal muscle, antagonized by the stiff cuticle
- when tension stops, cuticle causes them to spring back
How do they feed?
- muscular pharynx
- pseudocoelomic fluid pushes food down gut/intestine
Describe asexual reproduction
- a few species can do parthenogenesis
- no budding, fission or regeneration
Describe sexual reproduction (4)
- internal fertilization (males have copulatory claspers to hold female)
- mostly dioeceous
- amebioid sperm (no flagella)
- 4 moults to adult stage
Steps of nematode sexual reproduction
- egg
- 4 moults of juveniles
- adult
What is the purpose of dauer larvae?
- faculative diapause
- at juvenile 2
- way to survive adverse environmental conditions
Describe the hookworm life cycle
