1 / 11

Phylum Nematoda (Chapter 27.2)

Phylum Nematoda (Chapter 27.2). Please set up your notebook for Cornell Notes. Nematodes Characteristics Slender, unsegmented w/ tapered ends Range from microscopic to 1 meter long Most are free-living, some are parasitic Develop from three germ layers

clea
Télécharger la présentation

Phylum Nematoda (Chapter 27.2)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Phylum Nematoda (Chapter 27.2) Please set up your notebook for Cornell Notes

  2. Nematodes • Characteristics • Slender, unsegmented w/ tapered ends • Range from microscopic to 1 meter long • Most are free-living, some are parasitic • Develop from three germ layers • Have a body cavity b/w endoderm and mesoderm • Pseudocoelomate • Have a digestive tract with two openings

  3. Form and function • Feeding • Free living worms are predators with grasping mouth parts • Soil dwelling and aquatic forms eat algae, fungi or decaying organic matter • Respiration, Circulation and Excretion • These processes take place by diffusion

  4. Response • Simple nervous system with several ganglia • Numerous sense organs • Movement • Nematodes have muscles that extend the length of the body • Use the pseudocoelom and a hydrostatic skeleton

  5. Reproduction • Separate male and female organisms • Reproduce sexually using internal fertilization • Parasitic roundworms have life cycles that involve two or three host or multiple organs in one host

  6. Roundworms and Human Disease • Trichinosis  caused by Trichinella • Mate in intestines of host, larva are released into the blood stream to take up residence in various organs, become inactive cysts in muscles cells • Extremely painful • Common hosts are pigs and rats • Human contract by eating undercooked, infected pork

  7. Filarial worms  threadlike worms that live in blood and lymph vessels of birds and mammals • Transmitted by biting insects • Cause elephantitis extreme swelling due to buildup of fluid

  8. Ascarid worms • Ascarislumbricoides • Mature in intestine and release eggs in feces • Feces can contaminate food or water continuing cycle • Causes malnutrition

  9. Hookworms  soil dwelling • Lay eggs in soil • Pierce feet to burrow into skin and enter blood stream • Consume blood causing weakness and poor growth

  10. Pinworms  most common parasitic infection in US • Adults live in large intestine • Migrate to anal region to lay eggs • Results in intense itching that spreads eggs to clothes and bedding

More Related