Why do catfish get so big

Why do whales get so big?

Some land mammals can get quite large. But to find the true giants of the planet, you have to dive into the sea.

In a new study, scientists have now shown why this is so. Marine mammals need to "find a good average between an adequate food supply and adequate body temperature," says study director William Gearty, an ecologist at Stanford University.

It was previously believed that marine mammals could get so big because the buoyancy of the water freed them from some of the restraints of gravity. Although that can still be a factor, Gearty's findings show that marine mammals need to be large enough to keep warm in the often cold ocean.

“These animals are big for very specific reasons. It's not that they are big canbut that they be great have to", he says.


Gearty and his colleagues designed a number of computer models that analyzed factors that affected size. They found two factors that together determine the height of marine mammals.

The first factor is that the mammals must be large enough to hold enough body heat. Larger mammals give off significantly less heat to their surroundings, which, according to the models, gives them an advantage over their smaller cousins. The team's computer models were published in a study in Proceedings of the National Academy of Sciences.

However, larger mammals require more food, which is the second factor in Gearty's model. Large mammals are better at storing body heat, but if they can't find enough food to support their metabolism, it doesn't matter.

Height is one of the most important characteristics when studying animals, says Chris Venditti. The evolutionary biologist from Reading University was not involved in the study.