Nematoda

Question 1

What connects Clade Ecdyzoa?

Answer 1

a cuticle that molts, which is the process of ecdysis.

Question 2

What enzyme controls in molting?

Answer 2

ecdysone

Question 3

What are nematodes?

Answer 3

-roundworms that have no individual segments
-hard cuticle that keeps them solid and smooth so they can burrow into things

Question 4

Describe the internal morphology of nematodes?

Answer 4

• has a series of longitudinal muscles that work antagonistically with cuticle
  
  • when the longitudinal muscle contracts, the other side of the cuticle stretches
  • makes them good at moving through substrates
• Hypodermis: exterior skin, secretes the cuticle
• 2 nerve cords: dorsal and ventral nerve cord, runs through their hypodermis
• muscles extend dendrites to the nerves, instead of the nerves extending to the muscles
• pseudocoelom
  
  • endoderm, intestinal lining, is not lined with mesoderm
  • fluid filled

Question 5

Describe the external morphology of nematodes

Answer 5

• predominately very simple
• cuticle that periodically sheds
  
  • nonliving, protein based, stretchable
• females are slightly larger than males
• males have a hooked abdomen with a copulatory spicules
• mostly terrestrial, therefore reducing the amount of openings within the body to maintain moisture
  
  • has 4 different holes
    
    • mouth
    • anus
    • execratory pore (for osmoregulation)
    • genital pore
  • only animal to have a separate digestive, osmoregulation, and reproduction openings
  • has muscles around the openings that are physically controlled for water release

Question 6

How do nematodes digest and excrete?

Answer 6

• High pseduocoelomic pressure that aids in digestion and excretion
  
  • due to a hard cuticle and a fluid filled body
• intestines has no muscles therefore no peristalsis, so they have to eat in order for previous food to go down
• open their mouth forcefully & suck food within their mouth through a negative vacuum
• contract to open the anus, and due to the high pressure the waste is expelled forcefully

Question 7

Describe the respiratory and nervous system of nematodes?

Answer 7

• ganglia around the brain and the mouth, which sensitives and activates motor neurons
• ventral & dorsal nerve cords
• papillae, sensors throughout their body but heavily concentrated at the mouth
• no sensory bristles or hairs
• some can breathe through aerobic system
  
  • krebs cycle and cytochrome
• Some can other breathe through anaerobic systems

Question 8

Describe reproduction in nematodes?

Answer 8

• sex is separate
• male has a copulatory spicules and hooked abdomen
  
  • keeps the female open so sperm can be received in
  • does not transfer sperm
    
    • sperm is ameboid in creature, not ciliated