Animal growth is much more constricted in water than it is on land, a factor that explains why whales and other large sea life have not evolved to be bigger than they are. For years, researchers wondered why whales, despite their huge size, stopped growing larger over time. To shed light on that, a group of researchers from Stanford University studied both whales and elephant seals to figure out if the animals can go beyond their typical measurements.
The team found that, unlike land animals, aquatic creatures have certain size limits. Such evidence directly challenges previous notions that marine mammals will never stop getting bigger. The team gathered their evidence by analyzing the physical characteristics of 3,859 modern animals and 2,999 extinct species. That revealed land animals tend to quickly evolve once they move into aquatic environments. That shift is key because it is often better to big in the water. However, increased size is only beneficial up to a certain mass.
Whales and other larger marine mammals eventually hit a plateau because the bigger they get, the faster their metabolism. As a result, getting too big would make it incredibly difficult for them to find enough good. Though there are exceptions to the rule, this information reveals animals’ eating behaviors affect their size and sheds new light on animal evolution.
“If you’re going to measure one thing in an animal, it should be body size because that one thing is related to so many others,” said Chris Venditti, an evolutionary biologist at the University of Reading who was not involved in the new study, according to National Geographic. “If you know how big an animal is, you probably know something about how it moves and its metabolic rate.”
The research was published in the Proceedings of the National Academy of Sciences.