Many people are familiar with the annual growth rings in tree trunks. Most fishes have similar features in their bodies; their bones have alternating bands of dark and translucent tissue that indicate the passage of time. But the skeleton of a shark is made of cartilage, not bone. It turns out that vertebrae of whale sharks have rings like those in fish bones and tree trunks. How long does it take for a new “ring” to grow in whale shark vertebrae? Thanks to the atomic bomb, scientists determined that it takes about one year.
In Print: July 1, 2020