By shortening and bending through small muscles a flatworm
can change direction.
kidneys,brains and eyes
Flaworms have primativ kidneys called nephridiae.
Those nephridiae have the capability to remove waste
products. There is no need of a bloodcirculation
as oxygen is always available: The thin skin
is permeabel for oxygen.
The brains are very primitiv, They consist mostly of 4 ganglia,
2 of those ganglia are sensitiv for light. Flatworms are attracted
by light and are attracted by lights in the room,
sticking to the aquarium window. there are two nervebundels
on the underside of the flatworm, connected by commissures.
from egg to flatworm
In a egg three layers devellop, called: ectoderm , mesoderm and
endoderm. The ectodermic layers forms the skin and nerves.
Also the eyes are formed from yhe ectopic layer.
The mesoderm forms ehe nephridiae, the muscles , the ovaria
and testes. The endoderm forms the intestines, the pharynx and
the mouth. So the flatworm is basrd n three layers, this is called
a triblastic animal. Extoderm en endoderm are the oldest layers
in the years of the evolution, the mesoderm is the latest.
native species
It's easy to distinct the three native species , as they differ in
color, shape and length,polycelis nigra is black and has a lot
eyes-spots
Planaria Genocephalus is rather small and white
Planaria Lugubris is abundant .
Classification of the Worms
M.C. Escher and the flatworm
M.C Escher was fascinated by the flat body of the flatworm.
Ander werk van Escher is hier te zien.
A flatworm is flat , and has no idea of up and down.
It knows only light and dark and seems to be propelled by
an invissible forc. This all puzzled Escher and he thought
about the strange universe in which flatworms would live.
A flatworm has only two dimensions, Escher was fascinated by
the idea that if you produce a Mobius band from flatworms
the resulting flatworm would have only one surface.
Flatworms are common in clean,shallow waters were they
live submerged in the mud.
But they can also be found in marine and brakkish water.
There body is very flat, and they swim slowly.
These animals are hunters , alyhough its not quit clear how
they catche there prey. They hunt for waterflees (daphnia)
but can be feed with egg yolk and liver.
It takes about one month to grow up and become fertile.
The light shines through the body of this flatworm showing
a shadow of its excretional organ.
reproduction
They have the possibility to reproduce sexually or, most often ,asexually .
Mostly flatworms are hermafrodetic, wich means that they produce
eggs and sperm in one body.
Asexual reproduction can be done by dividing the body in two parts.
Flatworms have the ability to regenerate every part of there body.
In this way they survive damage done by there predators, like
the water insects.
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