Biology Questions and Answers
(also called solenocytes), excretory
ducts and excretory pores.
- What is an example of
freshwater flatworm? Due to
that habitat what is the
physiological problem that
these animals must solve?
Platyhelminthplanarias, have an internal ees of freshwater, likenvironment (^)
much morthe exterior ae concentrated nd so they present ain solutes than
tendency to gain water. These
organisms theto avoid cell death caused n need a drainage systemby excessive
water.
The problem is solved by the presence
of protonephridia locatelongitudinal channels in d alongthe animal (^)
body. Protonephridia have ciliated cells,
the flame cells, that pusthe body through excretory h water pores.outside
- Is the nervous system in
platyhelminthes more or less
sophisticated than in
cnidarians? What are the main
neural structures found in
flatworms? How is this neural
organization important for the
diversity of biological niches
explored by species of the
phylum?
Platyhelminthes present a more
sophisticatedcnidarians, as the first neural chor nervous system thands (^)
with ganglia (grouping of neurons)
appear, a characteristic of the
evolutionary nervous complexity. In platyhelmintprocess of increased (^) hes
one can note the beginning of the
cephalization pconcentration orocess, with af neurons (nervous cells) (^)
in the anterior portion of the body and
the appearance othe ocelli. f photoreceptor cells in
With the increaseanimals to perceive and to interactd capacity of these with (^)
the surrounds due to the increased
complexityis possible to f of their nind platyhelminthes in eural complexity, ita
variety oterrestrial,f environments, includin and with diverse ways ofg the life, (^)
like those that are parasites and those
that are free-living.
- What is cephalization?
How does lateral symmetry
favor cephalization?
Cephalization is the evolutionary
tendency onervous commanf concentration od in central structuresf the (^)
in which there are grouping of neurons
(i.e, brain and ganglia formation).Evolutionarily the cephalization process (^)
begins with the appearance of ganglia
(group of neurons) in platyhand reaches an apex in vertebrates,elminthes
animalswell-developed brain. with a cranial box to protect the
With lateral symmetry the divided into lateral portions, superior,body can be
inferior, anterior and posterior. These
portions mcontrolled in somust be integrated e manner and thisand (^)
need stimulated the appearance of
ganglial complexityhead, a privileged extremity of and of beings with athe
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