NematodaJenny Brooke David

Friday, April 21, 2023

Period 1

http://www.stanford.edu/group/parasites/ParaSites2006/Loiasis/Home.html

Sample Animals and Pictures

• Caenorhabditis elegans

• Tricinella spiralis

David Dallas-Orr

Body Cavity (coelom) present or absent

• Have a coelom

• Nutrients are transported in the fluid in the pseudocoelom

• The fluid under high pressure

David Dallas-Orr

Body Symmetry

• Bilaterally symmetrical

David Dallas-Orr

Nervous System

• Nematodes have a reasonably well developed nervous system.

• This is comprised of a circum-pharyngeal nerve ring made up from 4 nerve ganglia from which 6 longitudinal nerves extend down through the body

• There are also 6 shorter nerves which extend forwards towards the mouth.

David Dallas-Orr

Circulatory System

• Lacks a circulatory

system

David Dallas-Orr

Digestive System

• Alimentary canal: digestive canal issuing a track from mouth to anus

http://classes.seattleu.edu/biology/biol235/hodin/nematodePriapulidGroup/nematodes/formAndFunction.htm#excretoryPathway of food:

mouth (stoma) pharynx intestines rectum anusJenny Kim

Excretory System

• Nitrogenous waste is excreted through body wall

• Rennette gland to excrete salt to maintain osmoregulation.

Jenny Kim

Locomotion/Musculature

• Only longitudinal muscles for movement

• Moves by undulations or wave-like motions of the body. This produces a thrashing movement.

http://classes.seattleu.edu/biology/biol235/hodin/nematodePriapulidGroup/nematodes/locomotion.htm

Jenny Kim

Skeletal Type

• Hydostatic skeleton: Non-compressible fluid enclosed and pressurized in body cavity.

• Tough cuticle that coats body

• Cylindrical and un-segmented

http://www.newscientist.com/gallery/mg20327161300-enemy-within-human-parasites/3

Jenny Kim

SENSORY STRUCTURES/FEATURES

• Nematodes have peripherally located sense organs.

• Recent studies revealed the presence of true cilia in nerve processes connected with sensory organs.

• The body is covered in sensory bristles and papillae that provide a sense of touch.

http://www.ucmp.berkeley.edu/phyla/ecdysozoa/nematoda.html

Brooke Goycochea.

REPRODUCTION• A female may deposit

100,000 or more fertilized eggs per day.

• Different species of nematodes have various ranges of modes of reproduction.

• Reproduction is usually sexual and most nematode species are dioecious.  Some species, however, are hermaphroditic.

http://w3.rennes.inra.fr/umrbio3pE/equipes/nematodes/images/lamelle-460.jpg

Brooke Goycochea.

GAS EXCHANGE

• Have an alimentary canal but no circulatory system.

• Respiration and gas exchange occur by diffusion across the body wall.

• Both anaerobic and aerobic metabolism is common. http://www.ars-grin.gov/ars/SoAtlantic/fp/stpp/burelle/nematode.jpg

Brooke Goycochea.

Unique Features of Nematodes

• About 25,000 species are known but about 20 times more exist. There is little known about each nematode species even though they are numerous.

• It is said that if nothing but nematodes existed, they would preserve the outline of Earth and its many features.

• Humans host at least 50 nematode species.

http://www.ucmp.berkeley.edu/phyla/ecdysozoa/nematodesm.jpg

Brooke Goycochea

Quiz• 1. Which of the following do not have a Hydrostatic skeleton for support?

• A. Cnidaria• B. Platyhelminthes• C. Nematoda• D. Annalida

• 2. Which of the following have a circulartory system?

• A. Cnidaria• B. Platyhelminthes• C. Nematoda• D. Annalida

• 3. Which of the following does not has a different body symmetry in the group listed below?

• A. Cnidaria• B. Mollusca• C. Nematoda• D. Chordata

• What type of body symmetry does each of the different phyla have? (listed above)

Quiz• 1. Which of the following do not have a Hydrostatic skeleton for support?

• A. Cnidaria• B. Platyhelminthes• C. Nematoda• D. Annalida

• 2. Which of the following have a circulartory system?

• A. Cnidaria• B. Platyhelminthes• C. Nematoda• D. Annalida

• 3. Which of the following does not has a different body symmetry in the group listed below?

• A. Cnidaria• B. Mollusca• C. Nematoda• D. Chordata

• What type of body symmetry does each of the different phyla have? (listed above)• A - Radial B,C,D – Bilateral

Bibliography for beginning pix• http://riddlelab.msl.ubc.ca/images/maincelegans.jpg• http://images.google.com/imgres?imgurl=http://workforce.cup.edu/

buckelew/images/Trichinella%2520spiralis%2520male.jpg&imgrefurl=http://workforce.cup.edu/buckelew/Trichinella%2520spiralis%2520male.htm&usg=__-N5OebYUengR9rzBklrnegm5b0Q=&h=512&w=640&sz=27&hl=en&start=1&um=1&itbs=1&tbnid=To3n2v9H1z6ALM:&tbnh=110&tbnw=137&prev=/images%3Fq%3DTrichinella%2Bspiralis%26um%3D1%26hl%3Den%26sa%3DG%26ndsp%3D20%26tbs%3Disch:1

• http://www.cals.ncsu.edu/course/zo150/mozley/fall/nematode.jpg

• http://www.nottingham.ac.uk/bennett-lab/nematode.jpg

• http://web.pml.ac.uk/nematode/pictures/images/nematode5.jpg