Lecture_20

Lecture_20 - Some key terms to know by the end of this...

Info iconThis preview shows pages 1–11. Sign up to view the full content.

View Full Document Right Arrow Icon
Some key terms to know by the end of this presentation: Tube within a tube Anisakis Cuticle (all of the layers) Complete digestive system Buccal cavity Noncompressible fluid Pseudocoelom Longitudinal muscles Circular muscles C. elegans L. lumbricoides Hookworms W. Bancrofti L. Loa Dracunculus
Background image of page 1

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

View Full DocumentRight Arrow Icon
Phylum Nematoda (Part I) Basic properties of nematodes Anatomy of model system nematodes: Caenorhabditis elegans and Ascaris lumbricoides Properties of the pseudocoelom Properties of the cuticle Musculature and movement Several life cycles of parasitic nematodes
Background image of page 2
Phylum Nematoda (Greek nematos = thread) Roundworms = nearly circular cross section 90,000 Species identified Cross section is circular because the worm is holding in so much pressure that their sides bulge equally in all directions The body of a nematode has as much internal pressure as your own aortic artery! High pressure affects most of the nematode’s morphology and behavior
Background image of page 3

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

View Full DocumentRight Arrow Icon
High pressure lifestyle is successful! Marine mud ecosystems may contain 4 million nematodes per square meter Some terrestrial ecosystems have nematode populations estimated at billions per acre some species are free living, while other are parasitic in plants or animals
Background image of page 4
Nematodes are bilaterally symmetric and triploblastic “tube-within-a-tube” body form cavity (pseudocoel) between the wall of the gut and the body wall outer wall of the cavity is bounded by tissue derived from mesoderm and the inner wall by tissue derived from endoderm Quiz: what would the wall of the cavity look like if it were a true coelom?
Background image of page 5

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

View Full DocumentRight Arrow Icon
The Pseudocoel Filled with fluid or a gelatinous substance major function is circuclation and distribution of material throughout the body and also as a hydrostatic skeleton functioning in locomotion (high internal pressure comes in handy) complete digestive tract: anus is separate from the mouth and that food travel through the tract in only one direction
Background image of page 6
General Characteristics of Nematodes Body elongate, cylindrical, and tapered at both ends Body design is a tube within a tube, the outer tube being the body wall and underlying muscles and the inner tube being the digestive tract Between the tubes is the fluid-filled pseudocoelom , in which the reproductive system and other structures are found; the pseudocoelom is filled with hemolymph
Background image of page 7

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

View Full DocumentRight Arrow Icon
Background image of page 8
  General Characteristics cont. Although there are some structural differences between pseudocoeloms and coeloms, they confer many of the same advantages: A space within the body cavity allows for the reproductive and digestive systems to evolve more complex shapes and functions A fluid lined chamber offers protection to the gut and other organs; acts as a cushion The fluid filled body cavity acts as a skeleton - hydrostatic skeleton , providing support and rigidity for a soft bodied animal
Background image of page 9

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

View Full DocumentRight Arrow Icon
The Pseudocoel and the Hydrostatic Skeleton enclosure of noncompressible fluid ability of muscles to apply pressure to that fluid
Background image of page 10
Image of page 11
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/17/2008 for the course BIO 051 taught by Professor Land during the Fall '07 term at Pacific.

Page1 / 74

Lecture_20 - Some key terms to know by the end of this...

This preview shows document pages 1 - 11. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online