Small worms that live on the bottom of your pond or
in a ditch. They become active at night and hunt
for small prey like waterflies.
kidneys,brains and eyes of the flatworm
the intestines of the flatworm
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 a room,
sticking to the aquarium window.
This makes it easy to catch them. There are two nervebundels
on the underside of the flatworm, connected by commissures.
Anatomy of the flatworm
from egg to flatworm
In a egg three layers will develop, there are called:
ectoderm , mesoderm and endoderm. The ectodermic layers
forms the skin and nerves and eyespots.
Also some parts of the eyes are formed from the ectopic layer.
The mesoderm forms the nephridiae, the muscles , the ovaria
and testes. The endoderm forms the intestines, the pharynx and
the mouth. So the flatworm is based on 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 of flatworms
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 of eyes-spots
Planaria Genocephalus is rather small and white
Planaria Lugubris is abundant .
The three native flatworms.
By shortening theire small muscles a flatworm
can change direction. At night they are attracted by light.
M.C. Escher and the flatworm
Escher was fascinated by the behaviour of the flatworm.
A flatworm is completely flat, and has no idea of
up and down. It knows only light and dark and seems
to be propelled by magic. This all puzzled Escher
and he thought about the strange universe were
flatworms would rule there world.
Flatworms are one dimensional animals, So if you
forms a Möbius strip of flatworms, you have
formed an animal with 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, although 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.
Regeneration is a strange way of reproduction for flatworms.
Regeneration of flatworms
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.
Flatworm move by ising the cilia on the skin. Moving this way makes no
disturbance in the water, so they don't attrac the attention
of a fish and don't disturb there prey: waterflees.
flatworms in saltwater or Platyhelminthes
These flatworms have often bright and strange colors s they
are often very toxic. The live on the bottom of tropical seas.
