Arthropods
Arthropods make up the largest phylum of animals in the
animal kingdom. Arthropod means “jointed foot”. All
arthropods have jointed appendages. Arthropods also
have segmented bodies and an external covering called an
exoskeleton.
Insects
Insects are one type of arthropod. Insects have three
body regions: a head, a thorax, and an abdomen.
All insects also have six legs, one or two pairs of wings,
one pair of antennae, and a pair of compound eyes.
Six Legs
Antennae
Compound
Eyes
Parts Of The Head
Use the diagram below to identify the parts of the head
on your grasshopper.
The grasshopper has 5 eyes, two compound eyes and
three simple eyes. The antenna are sensory organs
located on the head.
Mouth Parts
Use the diagram below to identify the mouth parts on
your grasshopper. As you identify each part, try and
remove it with your tweezers.
The labrum is used to hold food. The mandibles are teeth
used to chew food. The maxilla are used to chew and
taste food. The labium is used to hold food while it is
being chewed. Now use the diagram below to locate the
external structures on your grasshopper.
A grasshopper’s eardrum, or tympanum, is located below
the second pair of wings on each side of the thorax.
Locate the tympanum on your grasshopper using the
picture below. The tympanum is used for hearing.
tympanum
Like all insects, grasshoppers have six legs. The front pair
are used for walking, climbing, and holding food. The
middle legs are also used for walking and climbing. The
hind legs are used for jumping.
Grasshoppers breath through tiny holes in their abdomen
called spiracles. Try and find these tiny holes along each
side of the abdomen.
close up of
one spiracle
A female grasshopper has a longer abdomen than a male
that ends with a four pointed tip called an ovipositor.
The ovipositor is used to lay eggs. Look and the end of
your grasshopper’s abdomen and determine if it is a
male or a female.
Internal Structure
Using your scissors, remove the three left legs. Next,
snip the end off the abdomen and insert the tip of your
scissors under the top surface of the abdomen. Cut
straight up the middle of the abdomen all the way to
the head. Only cut as deep as the exoskeleton or you
will cut through the organs.
Next, cut the same way up the bottom surface of the
abdomen to the mouth. Remove half of the exoskeleton
and pin it open as shown on the next slide. Locate all the
organs shown on the next slide.
start cutting here
stop cutting here
gizzard
brain
esophagus
rectum
anus
heart
(ovary)
The esophagus is used to swallow food. The crop, gizzard,
gastric ceca, stomach, large intestine, and small intestine
are digestive organs. The rectum stores waste and the
anus removes wastes from the body. The malpighan tub-
ules collect waste from the blood. In the female grasshop-per the
ovaries produce eggs. The testes produce sperm
in the male grasshopper.
Throw the grasshopper away, wipe your dissecting tools
off, wipe your tray out, and wash your hands with soap
and water. Answer the following questions on a sheet
of paper.
Questions & Conclusions
1. What is the largest phylum in the animal kingdom?
2. What does “arthropod” mean?
3. List three characteristics that all arthropods have.
4. What three body regions do all insects have?
5. Name four other characteristics that all insects have.
6. How may eyes does a grasshopper have?
7. What are the antenna used for?
8. How may different mouth parts does a grasshopper
have?
*more questions on next slide
9. Describe the function of the following mouth parts:
a. labrum-
b. mandibles-
c. maxilla-
d. labium-
10. What is the tympanum?
11. Where is it located?
12. How many legs does a grasshopper have?
13. Describe the function of the legs:
a. front legs-
b. middle legs-
c. back legs-
14. What are the spiracles used for and where are
they located?
*more questions on next slide
15. What is the function on the ovipositor?
16. Was your grasshopper a male or a female?
17. Describe the function of the following organs:
a. esophagus-
b. rectum-
c. anus-
d. malpighan tubules-
e. ovaries-
f. testes-
18. Name the six digestive organs in a grasshopper:
19. Why is a grasshopper classified as an invertebrate?
20. How is a grasshopper’s skeleton different from
yours?
21. List the animals we have dissected so far from least
complex to most complex: