Can design have multiple purposes? That is a question asked by some scientists in a study led by Jesse Barber of Boise (Idaho) State University. The specific design feature they studied is the flashing light of fireflies. Do they have more than one purpose for their flashes?
We always believed that a firefly flashes its light to attract mates. That is reasonable and true, but it is an oversimplification of what the flashing does. Many times living organisms have a warning system built into their design to let predators know they are not good to eat. Barber and his associates suggested that fireflies taste bad and that the flashing warns predators not to eat them.
To test this theory, the researchers put bats that had never been around fireflies into a cage with fireflies. The bats learned in two or three interactions that a flashing bug is not good to eat. Barber says the bats quickly did a routine of “catch, taste, drop.”
Barber’s team then painted the flashing end of some lightning bugs with two coats of black paint so the bats could not see the flashes. Bats faced with the painted fireflies took up to 45 minutes to learn not to try to eat them. It seems evident that the flashing of a lightning bug has more than one function.
It is easy for humans to minimize the design that is needed for life to exist on Earth. How do you feed massive numbers of birds, especially in the spring when winter has taken away most of their food sources, and their food needs are maximized as they lay eggs and feed baby birds? In the past scientists have shrugged their shoulders and imagined that there are food sources we don’t recognize that fill this gap until the summer season generates sufficient seeds and insects to sustain the growing populations. Similar problems exist for many other animals like bats that depend on insects for their nutritional needs.
In the April 2017 issue of Scientific American (page 84), there is an interesting report about previously unknown migrations of insects. We have known about monarch butterflies for some time, but this study by British researchers shows that migrations of insects are massive. Over southern Britain alone there are 3.3 trillion insects migrating. That is an average of 3200 tons of bugs moving through the skies over Britain every year. The study also reports that similar patterns have been observed in Texas, India, and China.
The complexity of this migration is astounding. Insects don’t live long enough for one bug to complete the migration. Researchers found that in some cases six generations were involved to complete a migration. The insects do not just get randomly blown about. They travel in a well-programmed pattern taking advantage of wind direction and speed. The elevation at which they fly to get the strongest support for their journey is carefully chosen. For a number of reasons, spring migrations are different from fall migrations.