What If Whales Got Their Legs Back?

Very vintage! Around 50 million years ago, an ancestor of the common day whale lived and walked on land with four legs., Like other aquatic mammals, such as dolphins and porpoises, this wolf-sized animal, known as Pakicetus, is part of the cetacean group., It is one of the earliest whales and the oldest cetacean discovered that had functional legs. And that begs the question - what if current day whales had legs? And, no, I’m not sure anyone actually asked for this, not a single soul, but I’m going to do it anyway. Whales today are much bigger than Pakicetus was. And I mean MUCH bigger. The largest whale, the blue whale, can weigh up to 180,000 kilograms and reach 30 meters in length.,, That is 4,000 times bigger than the estimated 45 kilogram Pakicetus, and 30 times bigger than the current largest land animal, the African Elephant, which weighs around 6,000 kilograms., As fish-eaters, this walking monstrosity would need to reside near coastlines or riverbeds so it could spend its days fishing in the water, similar to Pakicetus who ate fish as well as small land animals. However, since they are much bigger, if they stuck to their current diet and ate solely fish, these whales would need to feed more and therefore spend more time in the water. Perhaps they would look a bit like their other ancestor, Ambulocetus natans, whose name actually translates to “walking whale that swims.”, They lived about 50 to 48 million years ago and had shorter legs with webbed feet and was a similar size and shape of an American alligator., So when did whales lose their legs? Well, over the 15 million years following Pakicetus, they transitioned to a solely aquatic lifestyle and their limbs slowly became smaller and smaller.,, Eventually, their front limbs became flippers and their hind limbs became weak and unnecessary.,, However, according to a 2006 study, they didn’t completely lose their hind limbs until about 1 million years later, or 34 millions years ago., This study aimed to pinpoint the genetic changes that led to hind limb loss and discovered a drastic change that inactivated a gene essential for limb development called, and I’m not joking, Sonic hedgehog or Shh. Without Shh, they are unable to grow a partial or complete limb. Through evaluating dolphin embryos, which are a relative of the whale, the scientists found that the Hand2 gene, which turns on the Shh gene, was inactive and therefore hind limb development was impossible. They were able to trace back when this first occurred by using fossil data. But while this study helps to explain the evolution of whale hind limbs, the timeline is still up for debate, as the deactivation of Hand2 and subsequently Shh could have happened gradually up until our modern version of the whale came about. I for one am happy that these giants have to stay in the water in your world. In my world some whales still have legs and it is almost impossible to throw a beach party! So are there any other animals that you want us to talk about next? Which animal is your favorite? Let me know in the comment section below! Curious to know how we can engineer ourselves to live underwater? since water is H20, a combination of hydrogen and oxygen, can we get oxygen from water then too? Unfortunately, no, to get oxygen through water we probably need to have gills like a fish.