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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
Yuchen
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.
http://piginpond.com/bbs/board.php?bo_table=wallpaper&wr_id=190&page=2
Ross
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
Liviu Cengher
Sensory structures/features
• Sensory Bristles along the cuticle. (sensilla)
1.1
1.2
• Sensory organs at posterior, involved in reproduction.
(phasmids)
1.5
1.3
1.4
• Two Amphids located on the head
1.6
1.7
Amphids: Specialized
Sensillia that can
sense better than
normal ones on the
cuticle
http://piginpond.com/bbs/board.php?bo_table=wallpaper&wr_id=153&page=5
1.8
Liviu Cengher
Reproduction
2.1
• 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
2.2
http://piginpond.com/bbs/board.php?bo_table=wallpaper&wr_id=141&page=6
Female Rep. Organ
2.3
Liviu Cengher
Gas exchange
Diffusion across the cuticle.
3.1
O2, CO2, ETC.
3.2
O2
CO2
http://piginpond.com/bbs/board.php?bo_table=wallpaper&wr_id=164&page=4
Liviu Cengher
Other unique features, sketches
14.1
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”.
*
*
14.2
14.3
*
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.
*
*
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*
Ross
Pictures
http://www.wormatlas.org/ver1/handbook/fig.s/IntroFIG2.jpg
http://piginpond.com/bbs/board.php?bo_table=wallpaper&wr_id=188&page=2
Ross
Test Question 1
Food is processed in nematodes in which order?
a. Pharynx, stomach, intestines, anus
b. Oral cavity, pharynx, stomach, excretory ducts
c. Pharynx, intestines, excretory ducts
d. Oral cavity, intestines, anus
e. Oral cavity, pharynx, intestines, anus
ANSWER: E.
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Ross
Test Question 2
Nematodes have all of the following systems EXCEPT
a. Excretory
b. Circulatory
c. Skeletal
d. Nervous
e. Digestive
ANSWER: B.
http://piginpond.com/bbs/board.php?bo_table=wallpaper&wr_id=88&page=11
Liviu Cengher
Test Questions 3 & 4
Which of these breathe through their tough cuticle?
a.
b.
c.
d.
Onychophora
Arthropoda
Nematoda
Mollusca
Which of these feel through sensillia on their tough cuticle?
a.
b.
c.
d.
Nematoda
Brachiopoda
Cnidaria
Annelida
3. C
4. A
Those
Things
(because our ppt is on nematodes obviously)
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Liviu Cengher
Bibliography
Info:
•
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.htm
Pictures:
•
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
http://piginpond.com/bbs/board.php?bo_table=wallpaper&wr_id=171&page=4