1. Do rats use smell
to choose what
food to eat?

2.  Over 1% of a rat’s DNA is devoted to detecting odors.
 For a rat to smell, messages follow the rat’s olfactory
neurons to the olfactory bulb in the brain. 2000 tiny
structures called glomeruli on the olfactory bulb are
used to help the rat smell.
 Rats have a second scent organ, the vomeronasal
organ which is located right in a pouch in the nasal
cavity.
 Rats have between 500 and 1000 types of olfactory
receptors.
 I found no sure proof that rats don’t like the smell of
bleach and vinegar but the King County Health site
said to keep rats out of sewer pipes, use bleach or
vinegar to wash them—this hinted that rats might not
like these smells.

3.  “Rat Sensory World: Journey into a Rat's
World.” Rat Behavior and Biology,
ratbehavior.org. Jan. 24, 2012.
 “How to Get Rid of Rats.” Public Health-
Seattle and King County
www.kingcounty.gov. Jan. 25, 2012.
 “How Does Smell Influence
Behaviour.”Fancyrats. www.fancy-rats.co.uk

4. I think a rat will use
smell to choose food.
A rat will recognize
contaminated food
and stay clear of it.

5.  4 pieces of sausage
 4 orange slices
 4 chocolate chip oatmeal cookies
 Vinegar
 Bleach
 Eye dropper
 Paper plates
 1 rat
 Large Cardboard box

6. 1. Start with a hungry rat.
2. Take the two cookies and drop three
drops of vinegar on one of them.
3. Place the two cookies 1 foot apart on
plates inside the cardboard box.

7.  4. Place the rat on the other end of the box.
 5. Watch the rat and note which cookie she
chooses.
 6. Change the placement of the cookies and
repeat 9 more times. When changing the
placement of the cookies, move the plates and
not just the cookies to avoid contaminating the
cookie without vinegar.
 7. Repeat steps 1-6 with the orange slices, and
the sausage.
 8. Repeat steps 1-7 with bleach instead of
vinegar.

8. Sausage Orange Cookie
Vinegar 3 7 6
No 7 3 4
vinegar
Approached Approached Approached
Bleach the bleach the bleach the bleach
contaminated contaminated contaminate
food and then food and then d food and
would not would not then would
approach any approach any not approach
food. food. any food.
Never Never Never
No Bleach approached. approached. approached.

9. Oranges with and without vinegar
Sausage with and without bleach
The rat jumps out of the box
with the bleach smell

10.  I discovered that rats don’t care about vinegar
smell. Overall the rat went to the vinegar
contaminated food 16 times and the
uncontaminated food 14 times, which isn’t much
of a difference.
 This also shows that rats don’t care about smells
that won’t hurt them. In fact they might “like”
vinegar smell.
 I also discovered that once a rat smells that food
is contaminated with a non-food smell (or a
dangerous smell) that they will not approach any
food to stay safe. The rat literally jumped out of
the box with the bleach smell. Possibly the
bleach smell filled the box and thus overlapped
onto the uncontaminated food.