## What Do We Really Mean by Optimal Foraging?

Earlier in this module, we defined optimal foraging theory, which states that **organisms focus on consuming
the
most
energy while expending the least amount of energy**. It
is
important to
take this abstract concept and figure out how it relates to
crows dropping
whelks. First, recall the definition of **work.**

Recall
that
work done is
the same thing as energy expended. We can now alter
our
definition of
optimal foraging to say that **organisms focus on consuming the
most
energy while doing the
least amount of work.** Now recall
the
following formula you have learned in physics:

where *W* is work, *F* is a constant force, and *D* is the direction that the force is acting in.

Note that equation 1 applies to a system in which an object is moving in a constant direction, and is acted on by a constant force parallel to the direction of motion.

Now we can start to make our definition for optimal foraging theory specific to this module. That is, **the optimal foraging of crows refers to breaking open and consuming the biggest whelks while flying the shortest total vertical distance.**

Exercise 3: When the crows are flying up to the height they want to drop the whelks from, what is the force that is opposing them?