8-1

Nematodes

Pharynx and anus are the only muscular structures

Hypodermal cords

• Dorsal and ventral hold nerve cords

• Each side has excretory ducts

Muscles reach into nerves

Ascaris Life Cycle

Eggs - passed out with fecal material in the soil

• Take two weeks to be incubated and become infective

• Can be viable for months or even years that they could be infective after incubated

• Ingested - stomach acid weakens the coat and they hatch

Juveniles

• Burrow out through the intestine wall and go into the veins or the lymphatic system

• Goes into the right side of the heart, and then to lungs

• Burst out of the alveoli in your lungs — can trigger pneumonia

  • Gets stuck in the mucus in your lungs

  • Cilia beat and push the mucus into the trachea

  • Clear your throat and pops to mucus into your esophagus

• Return to the intestine and set up shop — takes 2 months

Arthropods

• Use the broad overview phylogeny for arthropods

• Can replace Chelicerata with arachnids, pycnogonida and merostomata phylogeny

Arthropod success

1. Versatile exoskeleton - helps protect them but can be heavily modified for different purposes

2. Segmentation – more efficient locomotion – wings

3. Direct oxygen to cells – restricts body size

4. Highly developed sense organs

5. Complex social behaviors

6. Use of diverse resources through metamorphosis – limits competition between species – offspring are not competing with parents for resources

Gas exchange & Excretion

Breathe through spiracles in the abdomen

Malpighian tubules

• Blind tubules - don’t go anywhere

• Connect to the gut and put the nitrogenous waste in the hindgut

Metamorphosis

Ametabolous - direct development

• Egg — juvenile — adult

• Praying mantis, grasshoppers

Hemimetabolous - incomplete metamorphosis

• Egg — nymph (wingless adult) — adult

• Cicadas, dragonflies

Holometabolous – complete metamorphosis

• Egg — larva (growth stage) — pupa (reorganization) — adult (reproductive stage)

• Flies, butterflies