Transcript Earthworms - Newton.K12.ma.us

They’re squiggly...
They’re wiggly…
They’re Earthworms!
An Introduction to
Earthworms
Hello Fourth Graders!
My name is Ernie the
Earthworm, how do you
do? Today I am going
to tell you all that
you’ve ever wanted to
know about
earthworms, and much
more! Oh, and if you
are wondering who
those two little
critters are at the
bottom left, those are
my friends Eddie and
Eli. They are here to
enjoy the slideshow
too! Let’s Go!
What are Earthworms?
Good question! Earthworms are called
annelids. Annelids are a group that have
long, soft bodies that are segmented, or that
have many parts. These parts, or segments,
look like a bunch of little rings. The scientific
name for these rings is annuli.
Earthworms are also invertebrates. That
means that they have no backbone. Actually,
earthworms have no bones at all! Can you
think of another animal or mammal that does
not have a backbone?
There are about 2,700 different kinds, or
species of earthworms! Wow, that’s a lot!
This is my friend
Edith. Do you
notice all of those
rings?
An Earthworm’s Body
Earthworms are usually reddish or reddish brown. The
average earthworm is about 10-12 inches long. As I
said earlier, our bodies are soft, and they are also quite
flexible. I can even tie myself into a knot! Nah, I don’t
want to do it right now….
Earthworms usually have between 100 and 200 annuli,
or segments. Something that these segments help us to
do is regenerate! Do you know what that means?
We also have 5, that’s right 5, hearts, and a brain that’s
located at the front of the body. Our mouths and our
bottoms are located at our front and back ends.
Next, my friend Herman will tell you a bit more about an
earthworm’s body.
Hi Ernie! Hey kids! I would like to tell you a bit about
the part of our earthworm body called the clitellum.
When I am a few weeks old, you will notice a lightcolored band forming near my front end. This is my
clitellum. My clitellum will someday help to form
cocoons. New baby worms will hatch from the
cocoons and I will have a family.
Hi Herman!!
Yup, Earthworms have hair!
Thanks Herman!
If you had a microscope
and looked really, really
closely at each
segment, you will see
something that looks
like a bunch of small
hairs or bristles. (And I'll
bet you thought worms
were bald.) These
bristles are called setae
(pronounced see-tee)
and they help me move.
I have four pairs of
these bristly hairs on
each ring or segment.
Hi everyone!
What do Earthworms eat?
You kids have great questions!
Earthworms have very small mouths, so
we can only eat very tiny things like
bacteria and fungi, which you couldn't see
unless you are looking through a
microscope. We also eat organic matter
like plants (mmmm, salad) and decaying
animals from soil. I guess that sounds sort
of gross!
Sometimes the bits of food are too big for
my mouth, so I moisten them to make
them soft and suck them right into my
mouth. (Don't try this at home, human
parents tend not to like this.)
How do Earthworms eat?
Since I have no teeth, I cannot really
chew my food like you do. I do have
something inside of me close to my
mouth called a gizzard. You might
have heard this word before because
birds, including chickens and turkeys,
have a gizzard almost like mine. As I
eat my food, some grains of sand and
soil get into my gizzard. These grains
of sand and soil push against each
other, mix with moisture and grind the
food into tiny pieces (kind of like my
own personal food processor). When
the food leaves my gizzard, it goes
into my intestine. The food is
dissolved there and absorbed into my
blood. Then it is carried to all parts of
my body to keep me strong, healthy
and slimy.
After our bodies have used up
whatever they need, we go to the
bathroom in the soil. Our waste
is called casting. You may think
that this is too much yucky
information for you, but
earthworms’ castings help fertilize
soil. Think about it this way…If
there are 500,000 worms living in
an acre of soil, we could make 50
tons of castings. That's like lining
up 100,000 one pound coffee
cans filled with castings.
Having worms around in your
garden is a real good sign that
you have a healthy soil.
Other ways Earthworms Help
the soil….
The earthworm is one of nature's top
"soil scientists.“ We have also been
called “nature’s plows” because we are
like free farm help. When we move
through the soil, we help to “turn” the
soil. That means that we bring down
organic matter from the top of the soil,
and we mix it with the soil below. Quite
helpful if I do say so myself!
We worms also help to increase the
amount of air and water that gets into the
soil. We break down organic matter, like
leaves and grass into things that plants
can use.
How do Earthworms move?
Earthworms have two sets of muscles: circular
muscles, which move around each segment, and
long muscles, which run through the length of the
body.
Actually, I'm pretty well-built, if I do say so myself.
When my circular muscles tighten up, my body
becomes thinner and longer. This movement by my
circular muscles squeezes my front end forward. My
other long muscles squeeze together and help move
the rear end of my body towards the front end, making
me look short and thick. So, this is how I move
forwards and backwards. My setae act like the brakes
on a car, helping me to slow down or stop. Pretty cool,
huh?
Next, Herman and his assistant will show you how it’s
done!
Short
and thick
Ernie
Long and thin
Ernie…
Very
Good!
Nice Job!
How do Earthworms breathe?
Worms do not have lungs
but I breathe through my
skin. I take in oxygen
through my skin and it
goes right into my
bloodstream. My skin
must stay wet in order for
the oxygen to pass
through it, but if I am in
too much water I will
drown. Just keep me
damp, moist and slimy.
Although if the water has
lots of air in it, I can stay
under for a long time.
Right, Herman?
You are
correct, my
friend!
How are baby Earthworms born?
Remember the clitellum? Well, the clitellum
holds both male and female reproductive parts,
which means that earthworms are neither male
nor female; we are both. We need to mate with
other earthworms, and while we are mating, we
form a cocoon on one of our clitellums.
The cocoons are much smaller than a grain of
rice and are yellow-colored. Each cocoon can
have 1-5 worms. If conditions are not right for
hatching, such as dryness, my cocoons can be
dormant, which means they do not hatch. If the
conditions are right, our babies will be born in 23 weeks! They are practically see-through, but I
think they are so cute! After about 6 weeks, the
babies are old enough to produce their own
babies, and the cycle starts all over again!
Where do Earthworms live?
Earthworms live underground in the soil.
Since we earthworms need to live in a
warm, dark, and moist environment, we
would not survive anywhere else.
We earthworms create burrows in the
soil. A burrow is a hole or tunnel
underground. In order to dig our
burrows, we eat the soil, and get rid of,
or excrete, waste as we move along.
How deep we dig our burrows depends
on how moist the soil is. If the soil is
drier towards the top of the soil, we will
move deeper. That’s why when it rains,
you may see a lot of my friends at the
surface!
Bob, come on
home for dinner!
Coming mom! I
just need to get
off of this curb
and into the soil,
and I’ll be right
there!
Earthworm’s Enemies
I know it’s hard to
believe, but worms
have enemies. Of
course, they are not
real enemies. I am
sure they are quite nice,
but they need to eat to
survive as well. Some
animals that I need to
watch out for are
shrews, moles,
hedgehogs, and birds.
Some cool, wormy, fun facts…
Did you know that…
In one acre of
land, there can
be more than a
million
earthworms.
The largest
earthworm ever
found was in
South Africa and
measured 22 feet
from its nose to
the tip of its tail.
Worms can eat
their weight
each day.
Even though worms don’t
have eyes, they can sense
light, especially at their front
end. They move away from
light and will become
paralyzed if exposed to light
for too long (about 1 hour).
Charles Darwin
spent 39 years
studying
earthworms more
than 100 years
ago.
Worms can grow a
new tail, but not
grow a new head
if they are cut off.
Large Worms!
Wow!
They are
huge!
Herman had to leave
early. He says
goodbye and thanks
for listening. We hope
that you enjoyed
learning all about your
slimy friends. Take
care of your classroom
worms, and remember:
observe, think, learn,
and have fun!
Goodbye
fourth
graders!
Herman the worm and facts:
http://www.urbanext.uiuc.edu/worms/index.html