Transcript Why dissect a grasshopper?

Dissection of a
Grasshopper
What is a grasshopper?
A grasshopper is an arthropod. It has
 Jointed appendages
 A segmented body
 An exoskeleton
Grasshopper Facts:
Country: Worldwide
Habitat: meadows, fields, and hedges
Length: up to 3 in. (8cm) but mostly 5/8 1 1/8 in. (15-30 mm)
Weight: almost nothing
Closest relative: katydid and cricket
Why dissect a
grasshopper?
 To identify the external and
internal anatomy of the
grasshopper
 To practice basic dissection
skills
Explore this site to learn
more about grasshoppers.
http://www.ris.net/~lawnman/hopfaq.html#
GUTS
Get ready to learn more as
we dissect a grasshopper!
Step One
 Identify the materials you will need for
your dissection.
Dissection
Tray
Hand lens
Materials, continued
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Ruler
Scalpel
Scissors
Eye dropper
Dissection pins
Forceps (tweezers)
Materials, continued
 Gloves
 Goggles
 And a grasshopper!
Study the external parts of
the grasshopper
Step Two: Identify the
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Head
Thorax
Abdomen
Notice also the eyes,
antennae, legs and
wings
Skeleton
 The grasshopper has
a hard exoskeleton.
That means its
skeleton is located
on the outside of its
body, not internally
like ours. This
skeleton is made of
chitin, a
carbohydrate.
The head
A Frontal View of the head
The compound eye
The grasshopper has two
compound eyes that
are made up of
hundreds of individual
eyelets.
Observe the antennae
The grasshopper's
head has two
antennae that are
able to feel and smell
what is nearby.
The mouth
 The mouthparts are
a set of movable
jaws that let the
grasshopper chomp
its way through grass
blades.
The mouth
 Labrum - the broad upper lip
 Hypopharynx - the tongue
 Mandibles - two heavy
blackish jaws with teeth along
the inner margin. The
mandibles move up and
down.
 Maxillae - two smaller jaws
that move side to side
 Labium - the lower lip
 Palp - maxillary and labial
palps are sensory
appendages
The thorax
The legs
 Using huge hind legs,
the grasshopper makes
gigantic leaps into the
air.
 Long legs are an
advantage for jumping,
because they increase
the distance over which
the jumper can push off
the ground
The legs, continued
When a grasshopper
jumps, it first
crouches down,
there is then a short
delay, and then off it
goes.
Back leg- knee
The leg, continued
 The two rear legs are
specialized and
strengthened for
jumping, while the
front two pairs are
used only for walking
on the ground
The Wings
The two pairs of
grasshopper wings
differ in shape,
structure, and
function. The hind
pair are responsible
for flight.
Close up of the wings
 After its springassisted takeoff, it
can unfurl its two
pairs of wings and
continue flying with
them.
The abdomen
 The hind region of
the grasshopper’s
body, the abdomen,
consists of 11
segments.
The Abdomen
The abdomen is built up of a series of upper plates
known as 'tergites' and lower plates known as
'sternites‘. It is held together by a tough yet
stretchable membrane
Determine the sex of your
grasshopper
Close up
Female
Male
Reproductive organs
Female
Reproductive organs
Male
Task
Draw a diagram of the external parts of the
grasshopper. Label at least the
following:
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Head
Thorax
Abdomen
Compound eye
Antennae
Wings (forewing and hindwing)
Mouth
Step Three: Measure
Measure
 Be sure to record the length of your
grasshopper.
 Measure the grasshopper from the tip of
the head to the end of the abdomen.
 We will collect these measurements at
the end of the dissection lab and
compare!
Step Four: The Dissection
begins:
 Position the grasshopper dorsal side up
 Carefully remove the protective sheath from the
scalpel.
 Hold the grasshopper firmly.
Cut along the dorsal surface
of the thorax and abdomen
Gently pull the
exoskeleton aside
You may wish to use the
dissection pins to make
viewing easier.
 Using a hand lens, identify as many of
the internal organs as possible
Digestive
System
 These are the parts of
the digestive system :
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Mouth
Esophagus
Crop
Stomach
Intestine
 Chewed food is stored in
the crop, digested in the
stomach, and absorbed
in the intestine.
Observe the digestive
system
A little closer
The crop, gizzard and
digestive caecae
 The digestive caecae
produce enzymes
which aid in digestion
Respiratory System
 You will probably NOT be able to see the
small holes. on the side of their bodies
without your hand lens. These holes are
called spiracles, each hole leads to a
large tube called a trachea. The large
tubes divide into small tubes that branch
out to all the cells of the body. This
system of tubes carries oxygen to the
cells and takes away the carbon dioxide.
Respiratory System
 Do you see anything
in your grasshopper
that resembles a
lung?
Respiratory System
 The grasshopper does not have a lung. How
then does it breathe?
 Air enters the spiracles and as the abdomen
expands and contracts, fresh air moves in and
used air moves out.
 The air enters the cells directly and is not
transferred to the blood- that’s why their blood
is yellow, not red- it contains no hemoglobin!
Circulatory System
The grasshopper’s
circulatory system is
open- that means that it
does have a “heart”, but
the heart is more of a
muscular tube that
collects the blood and
forces it to the front of
the body. The blood
freely flows throughout
the grasshopper
The Nervous System
 The grasshopper's
brain is located
between its eyes,
above the
esophagus.
Cool fact…
 The grasshopper does not use its brain
to walk or jump! It does that without a
brain.
 The brain is used to control the mouth
and to send sensory information to the
rest of the body.
Excretory System
 There are a number of tubules between
the large intestine and the stomach. The
outer end enters into the body cavity and
takes in the wastes. The wastes are
carried into the large intestine and out
through the anus.
Task
Draw a diagram of the internal organs
you identified. Include at least the
following:
 Intestines
 Crop
 Reproductive organs
Be sure to:
Properly dispose of your grasshopper
 Remove the dissection pins.
 Pick up the grasshopper and any organs
that you may have removed. Discard them
into the plastic bag provided.
 Be sure to dump the remaining liquid in the
jar as this is the last dissection.
 Sanitize scalpels and pins, rulers and hand
lenses and trays. Return them to the kit.
 Wipe down lab tables and discard gloves.
 http://www.uleth.ca/bio/bio1020/anim2sli.html
 http://www.amnh.org/learn/biodiversity_counts/ident_h
elp/Parts_Arthropods/grasshopper.htm
 users.rcn.com/.../ BiologyPages/I/Insects.html
 www.st-andrews.ac.uk/ ~wjh/jumping/legwrk.htm
 www.thetech.org/.../ about/grasshopper.html
 io.uwinnipeg.ca/ ~simmons/hopper4.htm
 http://www.howe.k12.ok.us/~jimaskew/botzo/hopper.ht
m
 http://wwwbio200.nsm.buffalo.edu/labs/tutor/Grasshop
per/
 http://io.uwinnipeg.ca/~simmons/16labman05/lb6pg17.
htm
 http://faculty.washington.edu/chudler/invert.html
 www.sdvc.uwyo.edu/ grasshopper/ghparts.htm