L18 : Movement in Earthworm - Body Movements, Science, Class 6 Video Lecture

hello friends this video on body
movements part 18 is brought to you by
example calm no more fear from exam so
now this was all about human beings that
how human beings move what are the
various parts oils where movement take
place what about other organisms do we
have a lot of other organisms like the
earth-tone snail snake cockroach so how
do these organisms move so let us
quickly have a look at all of these so
let's start with earthworm so a brief
intro to earthworm it is a reddish brown
there is real invertebrate invertebrate
that is they do not have the vertebral
column so if they do not have vertebral
column they basically do not have the
backbone which we have because of which
we are able to stand that is why Earth
one do not stand they just creep over
the ground mostly it is seen during
rainy season they are more visible
otherwise they live under the soil they
are often called as farmers friend
because presence of Earth warm in soil
increases the fertility of the soil so
the castings of earthworm they improve
the texture of the soil they improve the
unit the quantity of humors in the soil
so therefore it benefits farmers because
when the fertility of the soil improves
the crop cultivation or the crop
production also improves they live on
upper layers of soil but during the
rainy seasons in the shock since the
soil gets completely clogged with water
they tend to come out of the soil on the
surface and that is why we see them
whole during rainy season in terms of
food they they eat any living or dead
organic matter sometimes they can eat
some tiny worms which are present in the
soil or even dead plant parts so they
can feed on both living and dead matter
now when you look at the body of an
earthworm so the body is segmented from
head to tail so from the starting till
the
in and you can see that the body is
divided into segments like this this is
segment 1 2 3 4 so each of these is a
segment so this is one segment this is
another segment this is the third
segment so so on so the entire body is
divided into segments so that is why
these this type of forms are also known
as segmented worms now each segment is
separated from the next segment by a
partition and this partition is known as
septum now there is not one septum
obviously because there are so many
partitions here so the plural of septum
is septa so the entire body has a number
of partitions each segment has muscles
and bristles called setae so when you
look at each of these segments they will
have some tiny hairlike structures or
tiny spike like structures and those
structures are also muscular in nature
now since they are muscular in nature
what does that mean muscles help in
movement so basically these structures
will help the earth wall move from one
place to another so Ceti is one of those
structures which will help it to move so
when you look at it more closely you can
observe these tiny prisms here so these
are the bristles so now let's see how
exactly an earthworm roots when you look
at the body of an earthworm
they do not have holes so that is one
interesting thing that they do not have
bones so they are they move only with
the help of the muscles now in fact as
you can see that they are invertebrates
they do not have the vertebral column no
backbone because there is no bone in
their body now when it comes to the
muscles their bodies have two types of
muscles they have longitudinal muscles
as well as third
muscles now what happens is when you
look at an earthworm you see that
earthworms body is divided into segments
like this right now every segment has
two types of muscles circular muscles
and longitudinal muscles now how these
two types of muscles work now
contraction of circular muscles and
relaxation of longitudinal muscles that
causes a segment to extend so one
particular segment gets extended because
of that similarly when the vice-versa
happens that is contraction of
longitudinal muscles and relaxation of
circular muscles that causes a segment
to become short so basically what's
happening is so let me write it here so
whenever there is contraction of
circular muscles and relaxation of
longitudinal muscles so why will this
would happen because as I said that
muscles always working pairs so one when
one type of muscle is contracting the
other has to relax so when this happens
then over again so whenever this happens
then overall that particular segment
extend now when the opposite happens
that is when the circular muscles
relaxed and the longitudinal muscles
contract in that case overall the
segment will shorten so basically when
you look at it you see this is the head
of the earth one so first this portion
expands then what happens this portion
shortens the next portion expand so you
see here the portion
every time this yellow part shows which
portion expanded so gradually you see it
is moving in this direction so first
this part shortened is the next part
shortened then further the next part
shortened and that's how gradually this
earthworm is also
moving in the forward direction so I'll
leave it was at this point then it moved
in this much then it moves this much
then it moved this much this much and so
on
so gradually it is moving in the forward
direction so these contraction
introduction this expansion and
contraction of particular segments
allows the body to move forward now to
give it a better grip to move on the
soil they have City City that is the
bristle Santa muscles which are present
over their body so these bristles allow
them to have a good hold on the soil
that is why if you make an earth if you
take out a not one from the soil and put
it on a very rough surface you would not
see it moving very comfortably it will
move very slow because its structure is
designed in such a way that it can move
very comfortably on the soil so whenever
you look at an earthworm moving just try
to observe it closely you will see that
when it starts to the front part extends
and the rear part is fixed so if only
the front part will expand the end part
will remain fixed and again after
sometime the front part will remain
fixed and the real part will expect
expand and this is how it will move now
it doesn't move very fast because it's
this kind of expansion and contraction
obviously the movement is going to be
very slow so they move slowly so if
possible try to observe this movement of
Earth on so that will make you feel more
exciting because you know what you are
learning you will actually see there so
muscles help earth warm in movement now
how muscles help I think that's clear
now these two types of muscles with
their collaborative effort help them art
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