Anhinga
A Natural Selection & Genetics Activity
Anhinga
• Anhinga are a species of bird which live
on/near warm water. They are sometimes
called “knifebills” because of the unique shape
of their beak.
Feeding
• The knife-like beak is an adaptation for this
species because it allows the birds to stab
fish, which they carry back to their nest to
eat.
Environmental Catastrophe
• Recently, an oil spill occurred near a group of
Anhinga living on an island. As a result, many
of the fish have died, and the water has
become very dirty and dangerous.
New Food
• Since fish are now harder to find, Anhinga
have started eating insects to get the protein
they need.
Dominant & Recessive
• The “knifebill” is the most common (and the
dominant) trait for this anhinga population.
However, occasionally a recessive spoon-like
bill shows up in the population.
Generation 1
• Half of you have a homozygous dominant genotype (left
side of room)
• Half of you have a heterozygous genotype (right side of
room)
• What are your phenotypes?
(Write all this down under Generation 1 on your worksheet)
Data
• Record the number of each phenotype on
your page for the start of Generation 1
The Rules
• You will have 5 seconds to collect as much
“food” as you can.
• Food must be picked up and placed into your
nest with your beak.
– No picking up the food container
– Hold your “food pouch” to your belly
• When time is called, count the number of
“insects” you collected.
Life or Death
• The top 2/3 of the class will survive and
become parents in Generation 2.
• The bottom 1/3 are dead. 
Generation 2: Making Babies!
• Those who survived must pair up (gender
doesn’t matter).
• These two parents will produce ONE baby.
– Find one baby from those who died.
• Work together (all 3 of you) to create a Punnett
Square showing the possible offspring based on
both parents.
WARNING
• Remember that EVERYONE must do each step
on their own worksheet.
• Even if you died, you must show the Punnett
Square of your new parents.
Rebirth
• Spin a large paper clip to determine which
box/genotype the baby actually gets.
– Hint: Center the paper clip with the back end of
your utensil or a pencil, then flick it with your
finger to spin it.
Baby Phenotypes
• Babies must now choose the proper beak type
(utensil) for their genotype:
AA = Knife
Aa = Knife
aa = Spoon
Genotypes & Phenotypes
• Write down your Genotype
• Write down your Phenotype
• Record the whole-class phenotype numbers for
Generation 2 in the chart on page 1.
Feeding Competition #2
• You will have 5 seconds to collect as much
“food” as you can.
• Food must be picked up and placed into your
nest with your beak.
– No picking up the food container
– Hold your “food pouch” to your belly
• When time is called, count the number of
“insects” you collected.
Life or Death
• The top 2/3 of the class will survive and
become parents in Generation 3.
• The bottom 1/3 are dead. 
Generation 3-5
Repeat 3 more times (or as time permits):
1. Make Babies
–
–
Pair up and find a baby
Create Punnett Square and spin paperclip
2. Record Data
– Your Genotype
– Your Phenotype
– Class Phenotype Data
3. Food Competition & Counting
4. Life or Death
Graphing
• Use the Class Phenotype Data chart to create
a line graph of the number of Knifebills and
Spoonbills over time (generations).
Reflection Questions
• Answer the Reflection Questions on your
worksheet.
1. What type of variation existed within the anhinga population?
2. What does "survival of the fittest" mean?
3. How was this simulation similar to natural selection in the wild?
4. How was this simulation different from natural selection in the wild?
5. What adaptation allowed the most anhinga to live in the last 2
generations? Why?