I bet you didnt know How to calculate
I bet you didn’t know. . . How to calculate the age of a shark Teacher Guide Curriculum Areas Ages Pattern seeking Changes in old age Food chains 4 -11
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Who were the scientists? Eye lens radiocarbon reveals centuries of longevity in the Greenland Shark (Somniosus microcephalus) Nielsen J [1, 2, 3, 4]; Hedeholm RB [2]; Heinemeier J [5]; Bushnell PG [6]; Christiansen JS [4]; Olsen J [5]; Ramsey CB [7]; Brill RW [8, 9]; Simon M [10]; Steffensen KF [1]; Steffensen JF [1] Why do you think there are so many authors? Where do they work? How will they work together?
What did the scientists know? In the 1950 s, nuclear bomb tests released a lot of 14 C (carbon-14) into the atmosphere which was taken up by oceans, plants and animals. Radioactive decay of 14 C is predictable and measuring the amount of 14 C in a sample from an animal provides information that can be used to calculate the age of the sample. The shark's inner eye lens is sealed off from the rest of the body and is not altered after birth so measuring 14 C levels in the eye can determine the age of the shark.
What did the scientists do? Scientists analysed 14 C levels in the inner eye lens to estimate the age of sharks born since 1950. Scientists measured the length of sharks.
What did the scientists find out? Scientists found out that length and age of a shark are directly linked. Now they are using a calibration curve (length versus age) to estimate the age of other sharks. The longest shark was estimated to be 392 years old!
Quick activity Would height be a good measure of children’s age in your class or in the whole school? Resources knowledge of children’s ages or birthdays Line up the children in order of height. Ask for their ages/birthdays. Is there a pattern? Tsar Nicholas II and his children
Longer investigation Resources: knowledge of birthdays, tape measures or rulers, paper to record data in a table, square paper or computers for plotting graphs Measure your height (cm or m) Record your age (in months) Plot the data on a graph (height versus age) Tip: Children could collect data from their class or across the school.
What did you find out? Can you draw a line of best fit? Can you use this calibration curve (or line) to predict the age of other children? Can you extend the line to predict the age of older children or adults? Why does this produce some interesting results?
Questions for further learning What other features of a human could be measured to provide a reasonable calibration curve to predict age? You could try: head circumference, hand span, or foot length. What if the average lifespan of a human is 300 years? PMI: consider the positive, minus and interesting points that occur to you. Why might sharks live so long? Hint: research some food chains in the oceans. Unlike humans, sharks continue to grow throughout their lives. Are there other animals for which this applies? How can you determine the age of a fallen tree? Hint: look for concentric rings.
Maths links Area of learning Activity 12 times tables How old are you in months? Measuring length How tall are you (cm/m)? Plotting coordinates Plot a scatter graph Interpreting data Can you predict how old another child is?
Writing links Area of learning Activity Narrative Write a story describing the day the shark was measured (from the point of view of the shark or the scientist). Non-chronological report (newspaper) Explain what scientists have done and what they have found out. Instructions Explain how to measure a shark safely or how to measure you friend accurately. Argument / persuasive writing Should we protect endangered species such as hammerhead shark?
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