Transcript Slide 1 - Images

WORMS!
1.Part One – Unsegmented
Worms
• Their bodies are not divided
into specialized segments.
• There are two phyla:
– Platyhelminthes are the
flatworms
– Nematoda are the
roundworms
2. Phylum Platyhelminthes
They are the simplest animal
with bilateral symmetry.
Most members have enough
cephalization to have what
we can call a head.
3.They are usually only a few
millimeters thick but can be
several meters long.
• Flatworms feed in two
different ways. Some may be
carnivores or scavengers,
others are parasites.
4.The carnivores and
scavengers are free swimming
in streams, lakes, and oceans.
They feed on tiny aquatic
animals or dead aminals.
5.They have a mouth leading to
a pharynx which is used to
suck food into the
gastrovascular cavity.
6.They have intestines where
the food is broken down by
enzymes and absorbed by
diffusion into the tissues.
7.Parasitic flatworms feed on
the blood, body fluids, and
tissue of their host.
• Most have a more simple
digestive tract than free living
flatworms.
8. Tapeworms are flatworms
that live inside the intestines
of their host. They have no
digestive tract at all. They
have hooks that attach to the
intestine and take food that
has already been digested by
the host.
9. Flatworms do not have much
in the way of circulatory and
respiratory systems. Because
they are so flat they can
diffusion to transport
nutrients and oxygen to their
tissues.
10. They can also remove their
waste by diffusion.
• Flatworms that live in
freshwater have special cells
called flame cells they can use
to remove excess water from
their bodies.
11. Flatworms have a nervous
system with a distinct head
and a simple brain. They have
long nerve cords that run down
the length of the body and
short cords that run across it.
12. Many flatworms have one
or more pairs of light
sensitive organs called ocelli
or eyespots. They cannot form
images.
13.They also have
chemoreceptors that can
detect chemicals in the water
and locate food.
• Most parasitic flatworms do
not have nervous systems
because they do not need one.
15. Flatworms get around by
using the cilia on the ventral
side to help them glide around
AND they have muscles they
can use to swim.
16. Flatworms can reproduce
both sexually and asexually.
Most free living flatworms are
dioecious. They lay the eggs
in small clutches.
17. Asexual reproduction can
occur by fission or the worm
may simply fall to pieces.
Each piece will grow into a
new worm.
18. Most free living flatworms
belong to the class
Turbellaria. Most are less
than 1 centimeter in length
but in the tropics they can
reach lengths of 60
centimeters.
19. Members of the class
Trematoda include the flukes.
Most are internal parasites
that infect the blood and
organs of their hosts.
• Fluke life cycle
20. Class Cestoda includes the
parasitic tapeworms.
• They have a head called a
scolex that have several
suckers and a ring of hooks
that are used to attach to
the intestine of the host.
21. They are almost never
fatal but they can make the
host very sick and weak.
• The body is divided into
regions called proglottids. The
ones closest to the head are
small, the posterior ones are
large and full of eggs.
22. When they become mature
they break off and are passed
out with the feces. A single
proglottid may contain over
100,000 eggs. A single worm
can make over half a billion
eggs each year.
• turbellaria
• Trematoda - fluke
• tapeworm
23. The Phylum Nematoda are
known are roundworms.
• They are the simplest animals
to have a digestive system
with two openings ( a mouth
and an anus).
• They range in size from
microscopic to a meter.
24. They are just about
everywhere. A bucket of soil
may contain more than a
million.
• Most are free living but many
are parasitic.
• Free living roundworms are
often carnivores.
25. They breathe and excrete
their waste through the body
wall by diffusion.
• They have a simple nervous
system consisting of several
ganglia (groups of nerve cells)
in the head region. They also
have several sense organs
used to detect chemicals.
26. Roundworms reproduce
sexually. Most species have
males and females but some
are hermaphroditic (both
sexes on the same individual).
• Fertilization is internal
(happens inside the body).
27. Ascaris is the parasitic
roundworm that infects
humans. The adult worm lives
in the intestine where it
produces eggs that leave the
body in the feces. If food or
water that is contaminated
with the feces is eaten by
another host the eggs hatch in
their intestine.
28. The young worms burrow
into the walls of the intestine
and enter the blood stream.
They are carried around in
the blood until they end up in
the lungs.
29. Here they break out into
the air passages and climb up
into the throat where they
are swallowed and carried
back into the intestine where
the cycle start all over again.
30.Other parasitic roundworms:
• Hookworm
• Trichinella
• Filarial worms
• Eye worms
• 31. Hookworms are common
human parasites in the
southeast.
• ¼ of all the people in the
world are infected with a
hookworm. The eggs hatch
outside the body and develop
in the soil.
32. They will burrow through
the skin of an unprotected
foot and enter the blood
stream.
• From the blood they enter the
lungs and …
33. Trichinella cause the
disease trichinosis. They live
and mate in the intestine of
the host. The female with the
fertilized eggs release the
larva into the bloodstream.
They then leave the
bloodstream and burrow into
organs and tissues.
34. The larva form cycts in the
hosts muscle tissue which are
very painful.
• Humans get the disease by
eating infected pork that has
not been thoroughly cooked.
35. Filarial worms are found
mainly in the tropics. They
live in the blood and lymph
vessels. They are usually
transmitted by the bite of a
mosquito.
36. The infected persons blood
and lymph vessels can become
clogged with the worms. This
causes swelling in that part of
the body.
37. Eye worms are closely
related to filarial worms and
are found in Africa. They
affect both humans and
baboons. The worms enter the
blood stream and occasionally
move across the surface of
the eye. That’s how they get
the name.
• Roundworm
• Hookworm
• Trichenella cysts
• Filarial worms
• Caused by filarial worms
• Eye worms
38. Phylum Annelida
• These are the segmented
worms. They range in size
from less than ½ millimeter to
the giant earthworm more
than 3 feet long.
39. The segments of an
annelids body are separated
by internal walls called septa.
Most of these segments are
the same but a few are
modified to perform special
functions such a
photoreceptors, antennae,
etc.
40. The digestive tract is a
long tube from the mouth to
the anus. They have a
pharynx which is used to grind
up the larger particles of
food.
• Some annelids are carnivorous.
41. Carnivorous annelids can
extend the pharynx through
the mouth. These have two or
more sharp jaws attached to
it which are used to catch its
prey.
42. In earthworms the pharynx
acts like a pump pulling in soil
and detritus through the
mouth and forcing it into the
gut.
43. In parasitic annelids the
pharynx is used to suck blood
from the host.
• Some aquatic annelids are
filter feeders and use fan-like
structures to catch food
particles.
44.Aquatic annelids breath
through gills.
• Many annelids take in oxygen
and give off carbon dioxide
through their skin. The skin
must stay moist for this type
of gas exchange to occur.
45.Terrestrial annelids secrete
a thin protective coat called a
cuticle to hold moisture around
them.
46.Annelids usually have a
closed circulatory system with
two blood vessels running the
length of the body.
• In earthworms there are
several ring vessels connected
to these blood vessels in the
anterior part of the worm.
47.The ring vessels are
muscular and contract in
rhythm so they are sometimes
referred to as hearts. They
do help pump blood through
the system. In other annelids
the blood is moved around by
the worms movements.
48.Solid waste is removed
through the anus while waste
resulting from cellular activity
is removed by a pair of
nephridia in each segment of
the body.
49.Annelids have a well
developed nervous system.
• Sense organs are most
developed in the free-living
marine annelids. They often
have sensory tentacles,
photoreceptors, two or more
eyes, and statocysts.
50.A statocyst is an organ used
to detect gravity while they
are in the water.
• Many other annelids have
simpler sensory systems like
the earthworm. They rely only
on cells in their skin to sense
their environment.
51.Annelids have two major
groups of muscles they use to
move. Longitudinal muscles run
from the front to the rear.
These make the worm shorter
when they are contracted.
52.The other group runs in
circles around the worm.
When they are contracted
they make the worm skinnier.
These two muscle groups are
used together to help the
worm wiggle forward.
53.Most annelids reproduce
sexually but a few can
reproduce by budding.
• Palolo worm spawning.
54.Class Polychaeta
• Characterized by paired
paddle-like appendages on the
segments. The appendages are
tipped with bristles that help
the move about. They live in
the ocean, usually around
reefs.
55.Class Oligochaeta –
earthworms
• They also have bristles but
they are much shorter and
help the earthworm burrow
through the soil.
56.Class Hirudinea – leeches
• Usually no more than than 6
centimeters in length but some
tropical species can reach 30
centimeters.
• Most are freshwater and live
as ectoparasites drinking the
blood of their hosts.
57.They have suckers on both
ends of their bodies which are
used for attachment.
• After they attach to a host
they release a substance
called hirudin into the wound.
This keeps the blood from
clotting.
58.A leech can take in up to 10
times its weight in blood
during a single feeding.