FLATWORMS &
ROUNDWORMS
By: Nayarit Ayala and Marleni Cruz
FLATWORMS
PLATYHELMINTHES
STRUCTURE
Flatworms are flat, soft
bodied, ribbon shaped
unsegmented, contain no
body cavity, but they do
have digestive cavity.
They are bilateral
symmetrical, while
having only one
opening. Flat worms
have layers of tissues
that surround their
central gut. They are part
of the acoelomates, and
are considered
hermaphroditic. Their
type of cell layers are: an
ectoderm, which is the
outer covering, an
endoderm, which is the
lining of digestive
spaces, and a mesoderm
which is in between the
other two. No skeleton,
has tiny bristles called
cilia that help it move, it
has a combo of digestive
& excretory system,
takes food and gets rid
of wastes through the
same opening, has a
simple nervous system
with 2 nerve cords
running down either
side, has 2 simple brains
called ganglia ( bundles
) and 2 eyespots that
sense light. takes in
oxygen but has no
formal respiratory
system
DIVERSITY

Classification:

Domain: Eukarya

Kingdom: Animalia

Phyla: Platyhelminthes

Class: Turbellaria

Order: Seriata

Family: Planariidae

Group: Dugesia

What’s special about
flatworms?

Flatworms can regenerate if they
are cut, they will grow another
head if their cut is head. They
also have a layer which is in the
middle, that has unorganized
cells.
MODE OF NUTRITION



The organisms obtain nutrients by feeding on blood,
tissue fluids, or pieces of cells inside the bodies of
their hosts. All the nutrients are transported into
their single opening that leads directly to the
digestive system.
Studies show that platyhelminthes go through
anaerobic metabolism, which is not being dependent
of oxygen.
Oxygen is usually available. And it eats small worms,
insects and microscopic matter. they've developed
various feeding methods, turbellarians can feed on
organisms larger than themselves like annelids,
arthropods and mollusks. they have extracellular and
intracellular digestion. when intra, hematin is
deposited which is a pigment from hemoglobin.
REPRODUCTION
Flatworms reproduce sexually by having both a
male and female part. Each part that is split
becomes a separate worm, and they reproduce
asexually when it splits. It makes them
reproduce asexually. They have a cocoon that
carries eggs, swells in their body then , releases
the cocoon, and attach it to water weeds. The
cocoon has yolk, which nourishes the eggs. The
eggs are then hatched.
ECOLOGICAL SIGNIFICANCE
Importance of the
Organism



Through their large surface
compared to their volume they
can exchange gases like carbon
dioxide, oxygen and ammonia
across bodies. Flatworms can
adapt to many conditions, which
makes them able to adapt to an
enormous variety of habitats.
They play important roles
for healthy streams,
ponds, and lakes.
They also provide food for
animals, like dragonflies,
when they are young.
Interactions with
Humans



Flatworms act as
parasites in the human
body, especially in their
intestines and digestive
tracts.
They increase the
chances for organic
farming.
They increased the
popularity of raw cooked
foods, such as the
imports of meat,
seafood, and vegetables.
ECOLOGICAL SIGNIFICANCE
(CONT..)
Symbiotic relationships
with other organisms

They need symbiotic
relationships to
survive from fatty
acids.
Illnesses they may cause









Chronic Illness
Megaloblastic Anemia
Increase for bladder
cancer
Schistosomiasis
Tapeworm disease
(cestodiasis)
Cysticercosis
Joint Pains
Headaches
Fevers
UNIQUENESS
•Flatworms
can regenerate if a part of their body
is lost.
•They
reproduce with both sexual parts.
•They
can be up to 50 meters long.
•They
need symbiotic relationship to survive from
fatty acids.
•They
have a well developed nervous system.
ROUNDWORMS
NEMATODA
STRUCTURE
Roundworms are
bilaterally
symmetric.
Eyespots are spots
on the worm that
react to changes in
light. When the
light moves, it
sends signals to
the worm to move.
Roundworms use
some of their
nerves to detect
changes in light. A
roundworm is
thin, round,
smooth and can be
up to four feet in
length. A
roundworm has an
anus at its rear
end and a series of
excretory tubes
that end in an
excretory pore.
MODE OF NUTRITION
Roundworms usually eat algae, bacteria,
protozoa and fungi, some are filter feeders, eating
the waste of other creatures. They thrive their
nutrition in sediment and around plant roots.
 Free living roundworms feed on the decay for
organic matter and contribute to its breakdown
in the soil.
 They serve as decomposers and make nutrients
for larger organisms.

REPRODUCTION

Roundworms sexually reproduce, and they have
eggs and sperm. The male has sperm which pass
through the spicule over 200,000 eggs can be
deposited at once in the soil once they are
fertilized. Females have an ovary, and they are
meant to hold the eggs in an oviduct, then they
get passed into the uterus, after they lay their
eggs in the soil once they’re fertilized.
ECOLOGICAL SIGNIFICANCE
Importance of organism


Nematodes’ feeding, digestion, and
excretion allows minerals and
nutrients vital to plants and other
organisms to be recycled from
bacteria, fungi and decaying organic
matter and returned to the soil
where they are readily accessible.
They form a large part of the base that
supports the complexity of
life on earth. As consumers or more
specifically decomposers,
free-living roundworms recycle decaying
rotting organic matter present
in abundance in almost all
environments. They are a crucial link in
the chain of energy production and matter
recycling.
Interactions with
humans

They cause major
diseases and
infections to humans.
ECOLOGICAL SIGNIFICANCE
(CONT..)
Illnesses they may cause
Onchocerciasis
 Malaria
 Fevers
 Joint pains
 Headaches
 Diarrhea
 Nausea
 Abdominal cramps

UNIQUENESS
Roundworms have a thick cuticle that covers
their bodies and is shed in order to allow for
growth. Located between the cuticle and the
pseudocoel are muscles that run the length of the
nematode. These muscles push on both the
cuticle and the pseudocoel and create a kind of
hydrostatic skeletons. Unlike most animals whose
nerve cells branch out to each individual muscle
cell, nematode’s muscle cells branch toward the
nerve cells.
EXAMPLES




Ascaris (intestinal roundworm) – they’re found in humans and
are present mostly in unsanitary areas without plumbing
Hookworm – they’re found in warm regions and burrow
through skin they came in contact with their hook shaped
anterior ends allow them to latch onto the intestinal wall of
their hosts and feed on blood.
Trichinella is passed to humans through poorly cooked pork.
Elephantiasis is a human disease caused by filaria worms. It is
characterized by gross swelling and malformations due to
blockage of lymph vessels by the parasite. A mosquito is a
secondary host.
REFERENCES
(Brenda Priddy, 1999) http://www.personal.psu.edu/ncj111/Unique%20Features.htm
Biology4Kids.com: Invertebrates: Flat Worms. (n.d.). Rader's BIOLOGY 4
KIDS.COM. Retrieved February 24, 2012, from
http://www.biology4kids.com/files/invert_flatworm.html
Roundworms. (n.d.). University of Maryland Medical Center | Home. Retrieved
February 24, 2012, from http://www.umm.edu/altmed/articles/roundworms000144.htm
flatworm. (2012). In Encyclopædia Britannica. Retrieved from
http://www.britannica.com/EBchecked/topic/209735/flatworm
integument. (2012). In Encyclopædia Britannica. Retrieved from
http://www.britannica.com/EBchecked/topic/289723/integument
Raven, P. H., & Johnson, G. B. (1996). Biology. Dubuque, IA: Wm. C.
Brown Publishers.