How cetaceans got so large

WHY ARE whales so big? One answer is simply that they can be. The size of land animals is constrained in part by their need to support themselves against the force of gravity. Marine creatures have that support provided free, by the medium they live in. Even so, what is possible is not always sensible. Resources put into growth are unavailable for reproduction. Given that whales can and do become big, however, a second question arises: what, if anything, stops them being even bigger? Jeremy Gold...