Platyhelminthes: Characteristics and Adaptations
4. Phylum : Platyhelminthes
(platy -flat, helminth -worms)
e.g.
Planaria, Taenia
(Tapeworm),
Fasciola
(Liver fluke).
Salient features of phylum platyhelmintes:
*Habitat-
1.Animals are mostly
endoparasites
few are free living. (Planaria.)
* Body shape-
1.The body of these animals is
dorsoventrally
flattened with
bilateral
symmetry.
*Body organization:
2.They show
organ-system grade
of the organization.
*Germ layers-
3.They are
triploblastic
*Coelom:
4.
. They are
acoelomate.
.*Body plan –
5.
They
show
blind sac
body plan.
* Special feature-
6.
free
living forms are covered by
cilia
and
parasitic
forms have
hooks
and
suckers
for
attachment to the host body
.
7. In
parasitic
forms, the body is covered by a
cuticle.
8.
Digestive system
is
absent
in
parasitic forms
and
incomplete
in
free living
forms
.
9.
Excretion and osmoregulation
occurs by
flame cells
or
protonephridia
.
* Reproduction-
10.Animals are
hermaphrodite
(
bisexual
).
Self fertilization
is seen.
11.
Few
animals show
high power regeneration
and show
polyemryony.
Platyhelminthes, also known as flatworms, exhibit a dorsoventrally flattened body with bilateral symmetry. They can be endoparasites or free-living organisms, with some displaying unique adaptations for attachment and survival. These acoelomate organisms lack a complete digestive system, excreting waste through flame cells. Hermaphroditism is common, and regeneration abilities vary among species. Explore the diverse features and adaptations of this fascinating phylum.
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Presentation Transcript
4. Phylum : Platyhelminthes (platy -flat, helminth -worms) e.g. Planaria, Taenia (Tapeworm), Fasciola (Liver fluke).
Salient features of phylum platyhelmintes: *Habitat- 1.Animals are mostly endoparasites few are free living. (Planaria.) * Body shape- 1.The body of these animals is dorsoventrally flattened with bilateral symmetry. *Body organization: 2.They show organ-system grade of the organization. *Germ layers- 3.They are triploblastic
*Coelom: 4. . They are acoelomate. .*Body plan 5. They show blind sac body plan. * Special feature- 6. free living forms are covered by cilia and parasitic forms have hooks and suckers for attachment to the host body. 7. In parasitic forms, the body is covered by a cuticle. 8. Digestive system is absent in parasitic forms and incomplete in free living forms.
9. Excretion and osmoregulation occurs by flame cells or protonephridia . * Reproduction- 10.Animals are hermaphrodite (bisexual). Self fertilization is seen. 11. Few animals show high power regeneration and show polyemryony.
