“Where do large fish live?” asked one scientist to the other as their lines bobbed on the surface of the Florida Keys water. They were fishing – more like waiting for the fish to show up to be fished – and this casual question was posed to pass the time. What came out of it as not just a thought-provoking conversation but a paper that revolved around the very large size of one of the biggest “baddies” to ever roam our oceans.
Chances are you’ve heard of the Otodus megalodon shark, commonly portrayed in films as a gigantic monster of a shark that terrorizes Jason Statham and his crew. (“The Meg” fans can rejoice: filming has begun for the second movie starring Statham and this prehistoric behemoth.) A recent study reveals no one still knows what the Megalodon really looked like and DePaul University shark researchers say the mystery makes paleontology an exciting scientific field. Those same scientists have discovered something else that is quite peculiar about this extinct shark: it grew larger in cooler waters than warmer environments.
Chances are you’ve heard of the Otodus megalodon shark, commonly portrayed in films as a gigantic … [+]
getty
DePaul University paleobiology professor Dr. Kenshu Shimada and co-authors have taken a renewed look through time and space at the body size patterns this ancient shark that lived nearly worldwide roughly 15 to 3.6 million years ago. We only really know what we know about this species from their teeth and vertebrae in the fossil record, but it is generally accepted that they grow to be at least 50 feet (15 meters) and possibly as much as 65 feet (20 meters) long. After spending so much time with the remains, the team discovered a pattern. “Our findings suggest a previously unrecognized body size pattern for the fossil shark, notably following a geography- driven ecological pattern known as Bergmann’s rule,” said Shimada.
This rule was introduced in the mid-1800’s by German biologist Carl Bergmann and is known as one of the best-known ecogeographic patterns. Basically, it states that individuals within the geographical range of a species tend to be larger in body size under colder climatic conditions. This empirical generalization of course has exceptions, but it is widely accepted that us modern humans conform to Bergmann’s rule! But why the large size in colder climates? It is said their size helps them retain heat more efficiently compared to animals with smaller bodies. “Scientists constantly search for rules of life that help us predict natural patterns, and it seems that Bergmann’s rule applied to Otodus megalodon,” noted co-author Victor Perez, a paleontologist at the Calvert Marine Museum in Maryland.
We only really know what we know about this species from their teeth and vertebrae in the fossil … [+]
getty
This new study seems to unravel something scientists deduced about Megalodon: they may not have nurseries, after all. These “nursery” sites have been located near the equator were identified as possible nursery areas because smaller teeth on average were discovered here. “It is still possible that O. megalodon could have utilized nursery areas to raise young sharks. But our study shows that fossil localities consisting of smaller Megalodon teeth may instead be a product of individual sharks attaining smaller overall body sizes simply because of warmer water,” said co-author Harry Maisch, a faculty member at Bergen Community College and Fairleigh Dickinson University in New Jersey.
While it may not seem this information is pertinent to animals today, “the results of this study have important implications for understanding how modern climate change is rapidly accelerating marine habitat shifts to more polar latitudes in apex predators such as sharks,” noted co-author Michael Griffiths and professor of environmental science at William Paterson University.
What other Megalodon mysteries will be uncovered in 2022? Time will tell!
