Nematoda Flashcards
(24 cards)
What is the shape of Nematoda?
Cylindrical, thready shape – shaped like a worm.
What is the purpose of the cuticle in Nematoda?
Protect the body.
What are the multiple layers of the cuticle in Nematoda?
- Outer epicuticle (with glycolipids)
- Cortex
- Basal layer
What modifications can be found at the anterior end of Nematoda (both male and female)?
Cuticle modification:
* Cervical vesicle
* Cephalic vesicle
* Cervical papilla
* Cervical alae
What structures are found at the posterior end of male Nematoda?
- Copulatory bursa - extend caudal alae, supported by bursal rays
- Spicule
- Bursal rays
- Dorsal lobe
- Dorsal ray
- Lateral lobe
- Gubernaculum: guides the spicules during copulation - helps position and control the movement
- Tail is curved: bursae, alae, papillae, copulatory spicules
What is the hypodermis in Nematoda?
Thin layer right under cuticle – secretes cuticle during moulting.
What type of body cavity do Nematoda have?
Fluid-filled pseudocoel.
locomotor achieved by contraction & compress muscles at the cuticle on that side
What is the structure of the digestive system in Nematoda?
Simple, straight tube consisting of:
* Stoma (mouth opening)
* Buccal cavity with teeth
* Oesophagus (with oesophageal glands, bulb, isthmus, bulbus, muscular or glandular cells – stichocytes)
* Intestine (epithelial cells)
* Rectum and anus
* cloaca (male only)
Do Nematoda have a circulatory and respiratory system?
Missing.
What is the excretory system like in Nematoda?
Not well developed – consists of tubules and one excretory pore.
What is the structure of the nervous system in Nematoda?
Longitudinal nerve trunks connect the nerve concentration in the oesophageal region to the anal region.
Anterior: dorsal, ventral & lateral ganglia. 2 or 4 longitudinal nerve trunks with circumesophageal nerve ring
What are plasmids in Nematoda?
Small unicellular sensilia opening in the lateral tail region of some nematodes.
What is the reproductive system of Nematoda?
Sexually (except strongyloides spp.)
* Gonochorist - one sex
* Monociouds - female and male parts
* Males are smaller than females
What is the term for organisms with one sex in Nematoda?
Gonochorist.
What is the shell structure of eggs of Nematoda?
Three layers:
* Outer vitelline
* Chitinous layer
* Lipid layer (inner)
Describe the direct life cycle of Nematoda.
Egg, L1, L2, L3 (infective), L4, L5 (juvenile form of adult), adult.
What stages are involved in the indirect life cycle of Nematoda?
L1 - L2 - L3 (infective stage in most) - in intermediate host.
What is the infective stage for most nematodes?
L2 and L3.
What factors affect the hatching of L1 in Nematoda?
Temperature and moisture.
What are the two stages of moulting in Nematoda?
- Synthesis (new cuticle under old)
- Exsheathment (sheds old cuticle)
How many times do Nematoda moult during their life cycle?
Four times.
What are the classifications of Nematoda?
- Classes: Secermentea (Phasmidia) and Adenophorea (Aphasmidia)
- Orders: Ascaridida, Oxyurida, Rhabditida, Spirurida, Strongylida
Cuticle consists of … and has …
- Pseudosegments
- collar, oral capsule, teeth, moldings, papilla, wings & bursa copulatrix
cuticle can form many papillae
Life cycle of nematodes
- Indirect or direct
- Majority are gonochorists
- Majority of females are oviparous
- Majority reproduce sexually, within FH
- Eggs passed from FH to external environment
- Majority of eggs must go through 3 developmental stages before it is infective for host
- L1 development inside the egg - depend on temperature and moisture
- 2 moulting stages: synthesis & exsheatment
- Moults 4 times during their life cycle
- Infective stage is L2 & L3 in most species
- L1 is infective stage in Trichuris spp, Capillaria spp, Trichinella spp.
- L5 is in FH
- Can have IH &/or PH
