Cold War nuclear test residue offers a clue to whale sharks’ ages

Radioactive residue from Cold War nuclear tests has given scientists a cipher to decode the ages of whale sharks, written on the animals’ vertebrae.

Whale sharks (Rhincodon typus) accumulate alternating stripes of opaque and translucent tissue on their vertebrae as they age, similar to the way tree trunks grow rings. But until now, scientists haven’t known whether whale shark vertebrae gain a new growth band each year or every six months — making it difficult to gauge just how fast these sharks grow or how long they live. Read more.