Biology
Section______ Name__________________________________
Dr.
Wexler
Graphical Analysis 1
Date______
Sea gulls and crows feed on various types of mollusks by lifting them into the air and dropping them onto a rock to break open their shells. Biologists have observed that northwestern crows consistently drop a type of mollusk called a whelk from a mean height of about 5 meters. The crows appear to be selective; they pick up only large-sized whelks. They are also persistent. For instance, one crow was observed to drop a single whelk 20 times. Scientists have suggested that this behavior is an example of decision-making in optimal foraging.
Why do you think crows consistently fly to a height of about 5 meters before dropping a whelk onto the rocks below?
The figure below left shows the possible flight paths of northwestern crows when they are dropping whelks. The figure below right shows the detail of a whelk, a large marine gastropod (snail) found in temperate waters.
Think About This Situation
Consider the dropping of large whelks by northwestern crows.
Which flight path, A or B, do
you think the crows use most? Why?
What factors do you think influence the height at which the crows choose to drop the whelk?
Do you think there is a minimum or maximum number of drops required to break a whelk? Explain.
Do you think there is a minimum or maximum height at which a whelk can be dropped to break? Explain.
What classroom experiment could model the dropping of whelks to collect and analyze data?What questions would you attempt to answer in your experiment?