Transcript Aschelminths

Aschelminths
Roundworms:
Phylum Rotifera & Phylum
Nematoda
Some things to know about
Aschelminths…
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1. Aschelminths (roundworms) have a pseudocoelom. What is a
pseudocoelom?
– They have a body cavity, but it’s not in the mesoderm, meaning
that it’s not connected to anything.
– What were the flatworms?
2. They have a complete digestive tract, meaning a mouth and an
anus. And the mouth is actually on their head!
3. Can be microscopic to over 3 feet in length.
4. Roundworms are dioecious, meaning that they are either male or
female, not both.
5. Aschelminths have a cuticle, a thin, tough, external covering
that may have spines, scales, or other form of protection.
How and Where Do They Live?
Most live in freshwater. But like the
flatworms, some are marine, some are
terrestrial, and a few are even parasitic.
 Some (the rotifers) are even colonial.
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Phylum Rotifera
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Rotifers are microscopic
roundworms found in
freshwater. Can be found
living independently or
colonially.
The coolest thing about
rotifers, is that males are
very rare or nonexistent!
This means that the
females reproduce by
parthenogenesis. (They
don’t need a male rotifer
to get pregnant!)
Phylum Nematoda
Some of the most
abundant animals on
Earth!
 They can live in
freshwater, marine
habitats, soil, or as
parasites.
 Not only do
Nematodes have a
mouth, they also have
lips!
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Parasitic Nematodes: Trichina
Worms
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Trichinosis: Infection
comes from eating
undercooked infected
pork. Worms live in
the small intestine
and muscles of pigs
and humans. In the
muscles, the worms
can cause intense
pain and permanent
damage. Not very
common in the US.
Parasitic Nematodes: Filarial worms
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Filarial worms live in the
lymphatic system, blocking
vessels. This causes fluid to
back up and body parts
(usually legs) to swell. This is
called elephantiasis.
Transmitted by mosquitoes in
tropical climates. In the US,
the only type of filarial worm
that survives affects dogs –
heartworm. This condition is
usually fatal, so prevention
with heartworm medication is
the best thing to do for your
dog!
Parasitic Nematodes: Pinworm
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Pinworm: most common worm infection in the US,
usually in children. Infects the large intestine and anus,
causing intense itching. After scratching, children don’t
usually wash their hands and go on to infect other
children, their parents, or pets. However, this is easily
cured with an inexpensive medication from your family
doctor.
Parasitic Nematodes: Hookworm
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Found in the southern
US. Resides in the small
intestine, feeding off
human blood and body
fluids. Larval worms are
found in grass and soil
and usually enter through
the feet. Symptoms of
hookworm include
anemia and lack of
energy. Your dog or cat
can get hookworm, too.
Parasitic Nematodes: Ascaris
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The longest of all
parasitic nematodes.
They live in the small
intestines of humans, and
the eggs exit the body
with feces. The larvae
penetrate the intestinal
lining and infect the
lungs. This produces an
itchy feeling in the
trachea which makes you
cough. When you cough,
the larvae are swallowed
back into the stomach to
continue the cycle.