Before the meteor hit Earth at the end of 2021, river otters (Lontra Canadensis) were native to lakes, streams, and coastal marches. River otters were (and still are) semiaquatic mammals, and at the time they primarily fed on freshwater fish, but their diet also consisted of crawfish and insects. At this time, the river otter was still a very common animal, being on the least concern list in terms of how endangered the species was.
Then, when the meteor struck Earth on New Years, many of the river otters that lived in the lakes and streams were caught in the flood that followed and swept onto some of the coasts of the sea. The otters who were less proficient at swimming were killed in the flood, leaving the stronger river otters on the beach to fend for themselves. At this time, the population of sea otters had a massive drop, a big difference from their usual stable population numbers.
Comparison of a river otter and an earless seal.
As time passed, the river otter slowly adapted to its new environment. Through generations influenced by natural selection, the river otter actually became more genetically similar to the sea otter, even forming a symbiotic relationship with the other species. Though the river otter still kept its webbed hind feet and longer tails, they evolved to be almost twice the size they originally were, and they lost the thick layer of fat that used to help them stay warm in water. This is because the climate had become warmer when the meteor hit the Earth, so they no longer needed the fat to keep them warm.
As time passed, the river otter began to develop mutations in DNA that affected its evolutionary path. Charles Darwin's Theory of Evolution states that species change over time and give rise to new species. Darwin states that traits are passed down through generations which is what causes changes in DNA since the offspring are not identical. Evolution is controlled by natural selection and "survival of the fittest." Individuals with traits more suited to their environments have a better chance at survival and being able to produce offspring, and they will in turn pass these traits onto their offspring.
Darwin's Theories of Evolution can help explain the multiple evolutionary changes that the river otter has gone through. To survive, the river otter had to adapt to its environment, and one of the biggest changes that the river otter went through was the loss of its ears. The river otter lost its ears for the same reason the earless seals do not have any ears. The absence of the pinnae contributes to the animal's abilities to pick up on direction in hearing. In addition to this change, due to the increase in temperature the river otter also evolved to have a thicker patch of fur on the top of their bodies for shade, but thinner fur on the rest of their bodies to let heat escape easily since they no longer needed to trap their body heat.
So what is the future of the river otter? There has been a recent discovery that these peculiar otters have been developing some sort of gills, though they are not functional. Because of this discovery, some modern scientists believe that the river otter will evolve to be a fully aquatic carnivorous fish, especially since their teeth have evolved to be sharper and bigger, with the ability to easily snag fishes and other aquatic creatures. while others believe that it will someday return to the rivers that it once belonged to. The river otter has recovered in numbers since New Years, 2021, and the species seems to be here to stay for the forseeable future.