The largest sharks ever to have roamed the oceans parked their young in shallow, warm-water nurseries where food was abundant and predators scarce until they could assume their title as kings and queens of the sea.
But as sea levels declined in a cooling world, the brutal mega-predator, Otodus megalodon, may have found fewer and fewer safe-haven coastal zones where its young could safely reach adulthood, researchers reported on November 25 in The Royal Society journal Biology Letters.
Indeed, the reliance on nurseries may have contributed to the end of their 20-million-year reign, according to the research.
Otodus megalodon – sometimes classified as a Carcharocles megalodon – took 25 years to become an adult – “an extremely delayed sexual maturity”, the authors said in the research paper.
But once it was fully grown, the shark could reach up to 18m, three times the size of the largest great white shark, made famous by the 1975 hit-movie Jaws.
As an apex predator up until its extinction around three million years ago, the adult megalodon had no rivals among other ocean hunters and feasted on smaller sharks and even whales.
But its young were vulnerable to attacks by other predators, often other razor-toothed sharks.
Nurseries on shallow continental shelves with extensive smaller fish for food and few competing predators gave them the ideal space to reach their awesome size.
“Our results reveal, for the first time, that nursery areas were commonly used by over large temporal and spatial scales,” said the authors.
The research team discovered a nursery zone off the eastern coast of Spain in Tarragona province after visiting a museum and observing a collection of Otodus megalodon teeth.
“Many of them were quite small for such a large animal,” the authors from the British University of Bristol, Carlos Martinez-Perez and Humberto Ferron, told AFP.
The vast reduction of shallow water nurseries due to sea-level losses – caused by a cooler climate – may also have contributed to the shark’s eventual extinction.