Who is Stronger?
VS
Modified from
www.methacton.org/.../Bess%20Bug%20Lab.ppt
The Bess Bug
Odontotaenius disjunctus
Aliases
•Betsy Beetle
•Patent-leather
Beetle
•Passalid Beetle
Phylum Arthropoda Class Insecta
Order Coleoptera
• Largest order of organisms,
including over 350,000
species.
• One out of every four
animals in this world is a
beetle.
• They all have hard, shelllike forewings.
– A tough protector of the
beetle's delicate hind wings
and soft abdomen.
– Protects beetles as they
squeeze through narrow
passageways and burrow
into decaying wood or sandy
soil.
It’s Alive!
“The bess bug is
alive.” Defend this
statement using the
biological
characteristics of
living things
..\CharacteristicsofLivingThings_000.ppt
http://www.connecticutvalleybiological.com/isoto
pe/l/L%2051%20bessbug-95bab57e.jpg
Where Does it Live?
• Commonly found in decaying logs from Texas to
Florida and as far north as Canada.
• There are only two species in the U.S., while over
500 species can be found in the tropics.
Physical Characteristics
• Large, shiny, black
beetle
• 3 body parts - head,
thorax, abdomen
– The thorax of this beetle
has two sections,
allowing its hard body
to move more freely.
• 3 pairs of legs
– gold-colored fringe
• A pair of feathery
antennae
• Small horn and long
jaws protrude from the
front of the head
Diet
• They prefer hardwood—oak,
elm, and other deciduous
trees—that is well decayed
and falls apart easily.
• Wood is an indirect food
source.
– Beetles don't have symbiotic
bacteria in their gut that help
them digest the cellulose in
decaying wood. Bess beetles
process wood in their digestive
system, and then a fungus
grows on the beetles' feces. It is
this fungus that give beetles
nourishment.
• Larvae eat a well-chewed
mixture of beetle feces and
wood.
Other Fun Facts
• They are social insects and raise young in adult
pairs.
• Adults stridulate (shrill sound)by rubbing wings.
• Larvae stridulate by rubbing legs.
• Males have a prominent horn on their head.
• They have 2 pairs of wings but rarely fly.
Lab Purpose
• Observe and calculate the pulling power of a Bess
Bug.
• Determine the relative pulling strength of a Bess
Bug compared to a human.
• Discuss how strength is an adaptive advantage for
insects.
Strength?
* Brute Strength - How much can you lift/pull/push?
* Relative Strength - How much can you lift/pull/push in
comparison to your own body mass/weight?
• size (relative to their
own body mass)
• muscle arrangement
• muscle attachment
• body structure
• flexibility
Procedure Highlights
• If the bugs are scared or feel threatened, they may not
move.
• The harness should be placed between the thorax and
abdomen. It should go down their back!
http://www.youtube.com/watch?v=4G2fzRshi18
• The beetle should start on the cloth.
• The Petri dish should start on the table.
Procedure Highlights
• Any time the bug moves the dish, add a washer.
• Move the bug and Petri dish back to its starting position if it
gets off track. Do not pull or drag the bug. Pick it up!
• Handle the beetle gently and with respect!! Grasp it at the
sides.
• Carefully remove the harness and return it to the container
at the conclusion of the lab.
http://www.youtube.com/watch?v=GObVTjhuriI
Measurements
• Mass of a washer or
penny
• Mass of the Petri dish
• Mass of the Petri dish
with beetle
• Mass of the beetle
• Length, width, and
height of the beetle
Calculations
• Total pulled of
weights
• Beetle pulling power
..\1_Scientific_Method.pptx
Extra Credit
Problem 2: Is a Bess Bug
stronger than a human?
(Hint – you will need to
have a means of
comparison)