Can You Smell as Well as a Shark?!
Kelly
Original Source:
(but changed and added onto greatly)
Introduction:
Humans rule the land and sharks rule the sea but humans and sharks have another thing in common: we both have an olfactory system. Our olfactory system in our body allows us to breath and smell. Our noses work with our brains to pair the odor with a memory of what the odor represents, distinguish a new odor from the background odors and create a representation of the odor. The olfactory ability in sharks is well known for being spectacular but how well does yours work? This experiment will allow you to see if you can smell as well as a shark!
Goal:
To determine how well our noses work in detecting and identifying scents using scented products, food coloring and water.
Time to Get Ready:
10 Minutes
Time to Do Lab:
10 Minutes
What You Will Need:
- Six Cups
- Red Food Coloring
- Some Cologne, Perfume or other Scented Liquid
Lab Procedure:
- Fill each cup with 10 ounces clean water.
- In one cup place 10 drops of red food coloring. Stir gently to mix.
- In the second cup place 5 drops of food coloring. Stir gently to mix.
- In the third cup place only one small drop of food coloring. Stir gently to mix.
- Examine each cup.
- The remaining three cups should be well separated in the room.
- In one cup place 10 drops of cologne. Stir gently to mix.
- In the second cup place 5 drops of cologne. Stir gently to mix.
- In the third cup place only one small drop of cologne. Stir gently to mix.
- Hypothesize. Will you be able to smell the food coloring or perfumed cups better?
- Sniff each cup and note any differences.
- Try changing the concentrations of your mixtures and see how sensitive your noses are.
Questions:
Fill out chart according to your data.
1. Did you smell anything in the given cup, Y/N?
Cup #1 / Cup #2 / Cup #3 / Cup #4 / Cup #5 / Cup #62. What was the most potent smelling cup?
3. What was the lease potent smelling cup?
4. What is the system that allows us to smell and breath called?
5. Were you surprised by your ability to smell? How so? Did you think it was going to be stronger or weaker?
6. How do you think this adaptation (of a keen sense of smell) has helped sharks?
Biological Concept:
This lab gives students a greater understanding of their own olfactory system, which links into many other areas such as moving on from the olfactory system to the lymphatic, nervous and cardiovascular systems. This lab could lead to many great discussions and it would create a sense of awareness about their body and how it works.
Educational Concept:
Students will be able to hypothesize, observe, question and graph.
Benchmark(s) Addressed:
- Forming a hypothesis.
- Collecting and presenting data (also in the form of a chart).
- Analyzing and interpreting results.
- Grade 3: Recognize characteristics that are similar and different in organisms.
- Grade 3: Understand the characteristics, structures and functions of organisms.
- Grade 5: Describe the functions of organ systems.
Transformation of Concepts:
The chart helps students create organizational skills that are useful whenever they have data to arrange and present. Students could either move to other systems in the body (i.e. cardiovascular or nervous) or they could study the anatomy of a shark and other animal’s olfactory systems.
Extensions:
Students are able to test their smells in many, many other ways. This lab could be followed by a tasting lab where they would learn about parts of their tongue and taste buds.
How Much Will This Cost You to Present to 30 Students:
- Six Cups -- 24 cups @ $0.99
- Red Food Coloring -- 3 bottles @ $3.99
- Water -- Free
- Some Cologne, Perfume or other Scented Liquid-- Room Spray @ $2.99/bottle
Under $10!
Total for the Consumable Supplies for 30 Students:
About $5
How Long Would This Take You to Prepare Initially:
Preparation for this lab would take 10 minutes or less.
How Long Will This Take You to Prepare in Subsequent Years:
Less than 10 minutes.
How Much Time Will Your Students Spend on This Lab:
10 minutes for the lab but the questions will take about another 10 minutes or so.
How Long Will This Lab Take to Clean Up:
10 Minutes
Additional Information
Source:
Sharks possess a pair of nares or nostrils that are located just under the leading edge of the snout. Each nare is divided by a nasal flap into two openings. Water is channeled into the incurrent aperture and having passed over the olfactory lamellae exits the olfactory sac through the excurrent aperture. The olfactory lamellae are a series of folds on the interior surface of the olfactory sac which increase the surface area giving the shark more opportunity to register smells. Odors passing over the olfactory lamellae stimulate the cilia-like endings of neuro-sensory cells. What actually happens is, dissolved molecules transported along in the water column bind to receptor cells which then send a signal to the brain. This is referred to as a chemosensory function.
Sharks have olfactory bulbs which are anterior extensions of the large olfactory lobe in the fore-brain that lead directly into the olfactory sacs. fibers in the olfactory bulb continue directly into the olfactory tract. With such advanced hardware it is not surprising that sharks are able to detect fish extracts in concentrations lower than 1 part in 10 billion!
Once a shark picks up a scent trail it swims up the trail moving its head from side to side (which is its natural swimming motion). As its snout passes backwards and forwards through the scent trail it is able to determine the direction from which the odor is emanating. If the scent is lost or if the slick is too wide to use for navigation, the shark may swim forward in an exaggerated S pattern until it can pick up the direction again.
The nares are completely seperate from the mouth and throat and therefore do not aid at all in respiration. In order to detect odors, sedentary species are able to pump water over the nares whilst resting on the sea floor. Not all sharks require a highly developed olfactory system. Whilst sense of smell may be the prime hunting tool for an Oceanic whitetip shark swimming along in the featureless ocean, an angel shark laying in wait for a meal is primarily a visual predator and consequently its olfactory sense is not so finely tuned. However, odor detection is not only used in hunting. Sharks and rays produce pheromones which signal their reproductive state to potential mates and smell may also be used in navigation.
Oceanic whitetip sharks have been seen with their snouts out of the water supposedly sniffing the air. This may allow them to detect odors over far greater distances than would be possible under water.