Roundworms
Belongs to Phylum:
Nematoda
Roundworms are EVERYWHERE!!
•Roundworms are all around us.
•They vary in size from microscopic to a meter long
•A single rotting apple can have as many as 90,000
roundworms and a small bucket of soil or pond water
can have as many as 1 million
Main Characteristics of
Roundworms
•Unsegmented- meaning they have no
distinguished body parts
•Simplest animal to have a digestive system with
two openings-both an anus and a mouth
•Have a pseudocoleom-meaning their colon is not
completely covered in mesoderm
Anatomy of a Roundworm
• Simplest animals with a digestive system with two
openings – a mouth and an anus
• Have several ganglia-groups of nerves-but lack a brain
• Muscles run in strips along the length of the body walls
• Breath and excrete their metabolic wastes through their
body walls
Pseudocoelomates
• Roundworms
have a
pseudocolon
meaning that
they have a
colon that is
not
completely
covered by
mesoderm.
mesoderm
Roundworm infection
Heartworm
Guinea Worms Break out of skin when
mature
Ascaris Life Cycle
1.Adult worms live the intestines. Eggs
are passed with the feces
2. Fertile eggs become infective after
several weeks
3.Infective eggs are swallowed
4.the larvae hatch
5 invade the intestinal wall, and are
carried through circulation to the lungs.
6.The larvae mature further in the lungs
(10 to 14 days), penetrate the alveolar
walls, ascend to the throat, and are
swallowed.
7.reaching the small intestine, they
develop into adult worms
Roundworm Reproduction
• Roundworms reproduce
sexually
• Most species have
separate male and
female, though some are
hermaphrodites
• Fertilization takes place
inside the female
• She later then lays eggs,
which turn to larvae,
then to adult worms
Roundworm Egg
Affects on Human Life
• Though they are very
numerous around the
world, roundworms do
not exert a lot of positive
influence in the everyday
lives of humans so they
are easy to ignore
• parasitic roundworms are
responsible for some
terrible diseases
Heartworm
Hookworm
• Found in the tropics
• Nearly ¼ of the
population are infected
with hookworm
• The eggs hatch and
develop outside the
body of the host
• Burrow into unprotected skin (often
the feet) and enter the
blood stream
• Travel from the lungs
up to the pharynx and
are swallowed
• They dig into the
intestinal wall and suck
the blood of the host
• cause weakness and
poor growth
HOOKWORMS
Trichinosis
•The adult worms live and
mate in the intestines
•The females burrow into
the intestinal wall and lay
up to 1500 eggs
•This “burrowing” causes
Great Pain towards its host
Larvae
Cyst
Worm
• The larvae then travel
through the blood
stream until they find a
tissue to burrow into
• The larvae form cysts
inside the muscle
tissue of the host and
become inactive.
• complete their life cycle
when the muscle tissue
is eaten
(only carnivores can be
infected)
PIGS
• Most common animals
infected are rats and
RATS
pigs
• People get this disease
from eating not
completely cooked rat
or pork
Filarial Worms
• Found in tropics
• Thread-like worms
• Live in blood/lymph
vessels of birds and
mammals
• Transmitted by
mosquitoes
• Can block the vessels
– causing elephantiasis
(now rare)
Elephantiasis
Eye Worms
• Related to filarial
worms
• Found in Africa
• Infect humans and
baboons
• Live in sub-cutaneous
tissues
• Sometimes travel
across the eye