Phylum Nematoda and Others
Goals for today
• Learn to recognized the Phylum Nematoda
and 2 other smaller phyla from other animals
• Learn the main ‘diagnostic’ characteristics
• Learn about some free-living and parasitic
species biology
Phylum Nematoda: roundworms
Nematod are the most diverse phylum of pseudocoelomates, and
one of the most diverse of all animals
Key characteristics of the phylum:
•Body elongated and round body.
•Unsegmented
•Cuticle
•Nervous system with pharyngeal nerve ring
•Has no circulatory system
•Unlike cnidarians or flatworms, roundworms
have a digestive system that is like a tube with
openings at both ends.
•Pseudocoelomate
•Widespread and abundant in all habitats;
some parasitic
Phylum Nematoda: Your Tasks
Exercise 9A:
– Phylum: Nematoda
• Genus: Ascaris lumbricoides, A. suum
Ascaris lumbricoides is a common
intestinal parasite of humans. A.
suum paralyzes pigs. Nearly ¼ of
the human population is infected
with this roundworm. The eggs
are resistant to chemicals,
remaining viable in 2% formalin,
and 50% solutions of the
common laboratory acids
So be careful!! Use gloves and wash your hands after the dissection
Phylum Nematoda: Ascaris
1. Take a slide from your box with a cross section of a
male and female Ascaris.
Phylum Nematoda: Ascaris
2. Dissection. Use gloves at all times!
Select one sex and then
search for a student with the
dissection of the opposite sex.
Either can be in the exam!
Female
Male
Ascaris lumbricoides cont.
Female
gut
oviduct
genital pore
uterus
vagina
Ascaris lumbricoides cont.
Male
sperm duct
seminal vesicle
testes
gut
Male spicules
Phylum Nematoda: Your Tasks
Exercise 9A:
– Phylum: Nematoda
• Genus: Ancylostoma caninum (dog hookworm)
Observe a slide of the dog
hookworm. This is a common
parasite of domestic dogs and
cats. Try to note the cutting plates
which uses to attach itself to the
intestinal mucosa of its host.
Read page 161 on hookworms
Phylum Nematoda: Your Tasks
Exercise 9A:
– Phylum: Nematoda
• Genus: Trichinells spiralis (trichina worm)
Observe a slide of the trichina
worm a parasite of humans, hogs,
rats and other mammals
Your slide is a cyst of the parasite
Read page 162 on trichina worms
Phylum Nematoda: Your Tasks
Exercise 9A:
– Phylum: Nematoda
• Genus: Enterobius vermicularis (pinworms)
Observe a slide of a pinworm
which parasites humans in USA.
They live in the large intestine and
cecum.
Read page 162-163 on pinworms
Phylum Rotifera: Your Tasks
Exercise 9A:
– Phylum: Rotifera
Observe a slide of a rotifer: Rotifers
have a corona of cilia that is use for
swimming and feeding. The foot has a
pedal gland that secrets a cement to
cling on substrate. The mastax is fitted
with jaws for grinding food particles. The
body is cover by a cuticle which in
many roftifers is rigid and called
lorica.
They are pseudocoelomates
They live in freshwater, moist soil, mosses,
lichens, fungi, and even saltwater
Phylum Acanthocephala: Your Tasks
Exercise 9A:
– Phylum: Acanthocephala
Observe a slide of a spiny-headed worm. This worm is a parasite of pigs,
where it attaches to the intestinal lining and absorbs digested food from
its host. Like tapeworms it has not digestive system at all.
probóscide invaginable erizada de espinas
They are pseudocoelomates
Important Links
Nematods and others
http://www.savalli.us/BIO385/Diversity/13.Nematoda.html
http://en.wikipedia.org/wiki/Nematode
http://en.wikipedia.org/wiki/Rotifer
http://en.wikipedia.org/wiki/Acanthocephala
http://faculty.evansville.edu/de3/b10802/PPoint/Pseudocoelomates/sld0
01.htm