Download SENSORY STRUCTURES/FEATURES

Nematoda
Jenny Brooke David
Thursday, May 25, 2017
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/ho
din/nematodePriapulidGroup/nematodes/for
mAndFunction.htm#excretory
Pathway of food:
mouth (stoma)  pharynx  intestines  rectum  anus
Jenny 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/ho
din/nematodePriapulidGroup/nematodes/loco
motion.htm
Jenny Kim
Skeletal Type
• Hydostatic skeleton:
Non-compressible fluid
enclosed and pressurized
in body cavity.
• Tough cuticle that
coats body
• Cylindrical and unsegmented
http://www.newscientist.com/gallery/mg20327161300-enemywithin-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 • Different species of
100,000 or more
nematodes have
fertilized eggs per
various ranges of
day.
modes of reproduction.
• Reproduction is
usually sexual and
most nematode
species are
dioecious. Some
species, however, are
hermaphroditic.
http://w3.rennes.inra.fr/umrbio3pE/equi
pes/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
http://www.ars-grin.gov/ars/SoAtlantic/fp/stpp/burelle/nematode.jpg
common.
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/ne
matodesm.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/b
uckelew/images/Trichinella%2520spiralis%2520male.jpg&imgrefurl=
http://workforce.cup.edu/buckelew/Trichinella%2520spiralis%2520m
ale.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/bennettlab/nematode.jpg
• http://web.pml.ac.uk/nematode/pictures/images/nematode5.jpg