{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

The Tub1 - genome project Ascaris is a parasitic roundworm...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
The Tube-within-a-tube Body Plan: Phylum Nematoda The phylum Nematoda consists of several hundred thousand species of roundworms, shown in Figure 24. Most are free-living, although some are parasitic (pinworms are thought to infect 30% of all US children). Adult nematodes have a pseudocoelom (tube-within-a-tube), a closed fluid-filled space that acts as a hydrostatic skeleton, aids in circulation and dispersal of nutrients. Nematodes lack a circulatory system, but do have a well developed digestive system. One nematode, Caenorhabditis elegans , has only one thousand genes in its genome and its developmental pathways are well known. C. elegans serves as a model for eukaryote gene systems and has been extensively studied as part of the human
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Background image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: genome project. Ascaris is a parasitic roundworm, and is shown in Figure 25. These worms are unsegmented and have a smooth outside wall. They move by whiplike motions. Mating produces eggs that mature in the soil, limiting most roundworms to to warmer climates. When eggs are swallowed, larvae burrow through the intestinal wall, moving to the liver, heart and/or lungs. Once within the lungs, larvae molt and, after ten days, migrate up the windpipe to throat where they are swallowed. In the intestine, the mature worms mate and the female deposits eggs that are passed out of the body with feces. Feces must reach the mouth of the next host to complete the life cycle, thus, proper sanitation is an important aspect to prevent infection....
View Full Document

{[ snackBarMessage ]}