Nematoda By Liviu, Ross, and Yuchen Ross.

Nematoda

By Liviu, Ross, and Yuchen

http://media-2.web.britannica.com/eb-media/47/9847-004-9B39C5BB.jpg

Ross

Overview

• Nematodes are slender worm-like animals that are usually microscopic, but can grow to as long as 2 inches, or even a meter, long.

• Their bodies will often have ridges, rings, warts, bristles, hooks, etc.

• The main difference between nematodes (roundworms) and all other worms is that these are NOT SEGMENTED.

http://www.eb.tuebingen.mpg.de/core-facilities/microscopy-unit/sem_pictures/nematode.jpg

Ross

Phylum & Sample Animals

• Phylum: Nematoda• Sample animals: Roundworms. That’s it.• Metazoa: Animals with fixed body plan

– Eumatzoa: All animals but sponges•Bilateria: Bilaterally Symmetric

https://yhsbiology.wikispaces.com/file/view/roundworm.jpg/47735587/roundworm.jpg

Ross

Body Cavity and Symmetry

• Body Cavity - Nematodes have fake body cavities and thus are called Pseudocoelomate. The cavity is partially lined by tissue derived from the mesoderm. The other is separated by the digestive cavity that is not derived from the mesoderm.

• They are bilateral - if you cut them from the mouth you can only get one plane of symmetry. Think worms.

http://piginpond.com/bbs/board.php?bo_table=wallpaper&wr_id=195&page=2

Yuchen

Circulatory and Nervous System

• They DO NOT have a circulatory system ;_;• They DO have an Nervous system which

form an central ring near the anterior end of the nematode that forms a pseudo-brain. The rest is 4 nerve chords that run along the 4 sides (dorsal, ventral and laterals) of the worm. The dorsal is responsible more motor control while the laterals are for sensory. The thickest chord ventral combines the two functions.


Yuchen

Digestive System

•Food enters and exits the worm in this order: oral cavity, pharynx, intestines, anus

•Roundworms have no stomach

•The oral cavity is coated with a tough material called cuticle

http://www.inquisitr.com/wp-content/raccoon-roundworm.jpg

Ross

Excretory System

• Longitudinal excretory ducts. The waste is simply filtered through these ducts and taken outside of the worm.

• In simpler species, a unicellular gland called a renette cell pumps out toxins through an excretory pore.

http://s3.amazonaws.com/pixblix_production/art_images/1023/red-wave-abstract-background.jpg

Ross

Muscle System/Locomotion

• Underneath the epidermis lies a layer of muscle cells. These muscles are longitudinal (test question), meaning that they are unable to elongate the body and do not inch like earthworms or snakes do.

• Their movement is characterized by alternating contractions of the muscle, which looks like a thrashing or a wagging tail.

http://piginpond.com/bbs/board.php?bo_table=wallpaper&wr_id=199

Ross

Skeletal Type

• The cuticle is the closest thing a roundworm has to a skeleton because the cuticle is used for movement and support. There are no distinct joints.

http://piginpond.com/bbs/board.php?bo_table=wallpaper&wr_id=203

Ross

Sensory structures/features

• Sensory Bristles along the cuticle. (sensilla)

• Sensory organs at posterior, involved in reproduction. (phasmids)

• Two Amphids located on the head

Amphids: Specialized Sensillia that can sense better than normal ones on the cuticle

1.1

1.2

1.3 1.4

1.5

1.6 1.7 1.8

Liviu Cengher


• Both sexes possess one or two tubular gonads

• In males, the sperm are produced at the end of the gonad, and migrate along its length as they mature.

• In females, the ovaries each open into an oviduct and then a glandular uterus Male Rep. Organ Female Rep. Organ

2.1

2.2 2.3

Liviu Cengher

Reproduction


Gas exchange

Diffusion across the cuticle. O2, CO2, ETC.

Semi Permeable Cuticle

O2

CO2

3.1

3.2

Liviu Cengher


Other unique features, sketches

They have a tough Cuticle (a mass of cellular material and nuclei without separate membranes that coats the body) which is periodically shed.

The word "nematode" comes from a Greek word Νεμα (Nema), which means "thread”.

Nematodes are able to suspend their life processes completely when conditions are unfavorable, then return to life when favorable conditions return. This is called cryptobiosis.

14.1

14.214.3

** *

* * *

Liviu Cengher


Pictures


http://www.wormatlas.org/ver1/handbook/fig.s/IntroFIG2.jpg

Ross

Test Question 1

Food is processed in nematodes in which order?

a. Pharynx, stomach, intestines, anusb. Oral cavity, pharynx, stomach, excretory

ductsc. Pharynx, intestines, excretory ductsd. Oral cavity, intestines, anuse. Oral cavity, pharynx, intestines, anus


Ross

ANSWER: E.

Test Question 2

Nematodes have all of the following systems EXCEPT

a. Excretoryb. Circulatoryc. Skeletald. Nervouse. Digestive

Ross


ANSWER: B.

Test Questions 3 & 4Which of these breathe through their tough cuticle?a. Onychophora

b. Arthropoda

c. Nematoda

d. Mollusca

Which of these feel through sensillia on their tough cuticle?a. Nematoda

b. Brachiopoda

c. Cnidaria

d. Annelida

Liviu Cengher

3. C

4. A(because our ppt is on nematodes obviously)

Those Things


BibliographyInfo:• http://www.ucmp.berkeley.edu/phyla/ecdysozoa/nematoda.html• http://www.sci.sdsu.edu/classes/bio201/Nematodes.html• http://www.cals.ncsu.edu/course/zo150/mozley/fall/studyaids.html• http://www.esn-online.org/Nematodes• http://www.ucmp.berkeley.edu/phyla/ecdysozoa/nematoda.html• http://www.wormatlas.org/male/malehomepage.htmPictures:• 11.1 Created by Liviu Cengher• 11.2 http://web.pml.ac.uk/nematode/nematodes/index.htm• 11.3 http://www.cals.ncsu.edu/course/zo150/mozley/fall/studyaids.html• 11.4 http://www.wormatlas.org/maleHandbook/figsMale/MaleEpiFIG14A.jpg• 11.5 http://www.esn-online.org/Nematode%20picture%20of%20the%20week• 11.6 http://web.pml.ac.uk/nematode/nematodes/index.htm• 11.7 http://tolweb.org/Nematoda/2472• 11.8 http://web.pml.ac.uk/nematode/nematodes/index.htm• 12.1-12.3 http://www.cals.ncsu.edu/course/zo150/mozley/fall/studyaids.html• 13.1 http://bioweb.uwlax.edu/bio203/s2007/eddy_greg/images/nematode.jpg• 13.2 http://www.ucmp.berkeley.edu/phyla/ecdysozoa/nematoda.html• 14.1 http://tolweb.org/Nematoda/2472• 14.2 http://www.esn-online.org/Nematode%20picture%20of%20the%20week• * PowerPoint Clipart

Liviu Cengher


Nematoda By Liviu, Ross, and Yuchen Ross.

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