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Lundkvist
Biology 11
UNSEGMENTED WORMS
Read pages 570-578 in Miller & Levine and fill in the blanks.
1. Unsegmented worms don’t have their bodies divided into
_segments______________
2. The Phylum __Platyhelminthes____ consists of simple animals called
_flatworms____.
3. The phylum __Nematoda__ consists of long thin worms called
_roundworms_____.
Flatworms
4. The members of the Phylum Platyhelminthes are the simplest
animals with __bilateral symmetry___.
5. Free living flatworms have a ____gastrovascular cavity____ with one
opening at the end of a muscular tube called a _pharynx__.
6. The gastrovascular cavity forms a tube with many __branches__ along
the entire __length______ of the worm.
7. Because the intestine __branches__ into nearly all parts of the
body, completely __digested__ food can __diffuse__ to other body
tissues.
8. Like Cnidarians, flatworms expel __undigested___ materials through
the _mouth _.
9. Many other flatworms are _parasites__ that feed on blood,
_tissues___ or pieces of cells inside the body of their host.
10. Many parasitic flatworms have simpler __digestive tracts____
than free living flatworms.
11. Tapeworms, which live within the _intestines_ of their host, do
not have any __digestive tract__ at all. They have ___hooks__ and
/or suckers with which they latch onto the __intestinal wall___ of
the host. From this position they can simply _absorb__ the food
that passes by.
12. Flatworms lack any kind of _circulatory_ or _respiratory
system_. Because they are flat, they can depend on__diffusion__ to
transport _oxygen__ and _nutrients_ to their tissues.
13.
Label the diagram of the planarian:
1.
Oceeyes
pot
2.
4.
3.
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Biology 11
14. They can get rid of __carbon dioxide__ and most other
_metabolic__ wastes by allowing them to _diffuse_ out through their
body walls.
15. Freshwater flatworms such as _planarians_ have structures called
_flame cells__that help them get rid of extra _water_.
16. Free living flatworms have _nervous systems__ that are much
more developed than those of _cnidarians_ and ___sponges__. They
have a definite _head_ in which a simple _brain_is located. This
is the _control_ center of a simple nervous system that stretches
throughout the _body_.
17. Many flatworms have one or more pairs of __light-sensitive__
organs called _ocelli__ or ____eye spots__.
18. Parasitic flatworms do not have much of a _nervous system_.
19. Reproduction in flatworms can be either _asexual_ or _sexual__.
20. Parasitic flatworms do not reproduce _asexually_. They have
complicated_life cycles_.
21. There are three classes of flatworms. Free living flatworms
belong to the class _Turbellaria__. Parasitic flatworms known as
flukes belong to the class __Trematoda__. Long flat parasitic
flatworms that live a very simple life belong to class _Cestoda_.
Roundworms
22. Roundworms belong to the phylum __Nematoda__.
23. Roundworms are among the simplest _animals_ to have a digestive
system with _2_ openings – a mouth and an _anus_.
24. Most round worms are _free living__ but there are many
_parasitic_ roundworms.
24. Like flatworms roundworms breathe and excrete their __wastes_
through their _body walls_.
25. Roundworms have a simple _nervous system_. They have several
_ganglia_ or groups of nerve cells, in their _head_ region but they
lack anything that can really be called a _brain_.
26. The muscles of the roundworms run in strips down the _length_of
their body _walls_.
27._Ascaris_ is a parasitic roundworm that lives in humans. Adult
ascarid worms live in the _intestines__where they produce many
__eggs_ that leave the host’s body in the _feces_. If food or
water _contaminated_with these _feces_ is eaten by another host,
the _eggs_ hatch in the small intestine of the new _host_. The
young worms burrow into the walls of the __intestines__ and enter
surrounding _blood vessels_.Carried around in the __blood_ the tiny
worms end up in the _lungs__. Here they break out into the __air
passages_ and climb up into the __throat_, where they are
swallowed. Carried back into the intestines, they __mature__ and
the __cycle__ repeats itself.
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Biology 11
28. Parasitic roundworms include _hookworms__, __trichinosis_-causing
worms, filial worms and _eye_-worms.
29. As much as ¼ of all people in the world today are _infected_ with
_hookworm_.
30. _Trichinosis_ is a terrible disease caused by the roundworm
__Trichinella__. Two very common hosts of trichinella are
_rats_and _pigs_.
31. _Filarial_ worms are threadlike worms that live in the blood and
lymph vessels of _birds _ and _ mammals __. They are transmitted
from one primary host to another through _biting__ insects. In
severe infections large numbers of __filarial_ worms block the
passage of fluids within the __lymph_ vessels causing
_elephantiasis__.
Trichinella worms
Elephantiasis