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The Enthralling Nature of Marine Mammal Evolution

by Holly Chavez Blog

The most noticeable physical changes include the streamlining of every marine mammal’s body. Each mammal used to have more noticeable ears, and their bodies also once contained hind limbs. Now whales and other marine mammals have small holes that they hear out of, and they have developed a cylindrical body type to improve their swimming ability and reduce heat loss.
Antarctic Peninsula

The Enthralling Nature of Marine Mammal Evolution

There are many fascinating marine mammals found near Antarctica and in the Arctic Ocean, but most of them have different traits now than their ancestors did thousands of years ago. Going on an expedition in these regions is exciting without possessing a basic understanding of how the most prevalent marine mammals have evolved, but it becomes much more interesting when you are able to compare and contrast these creatures versus the ones that roamed the earth several centuries ago.


In fact, the enthralling nature of marine mammal evolution is something you’ll want to learn about and experience first-hand.

How Does Evolution Help These Marine Mammals?

Evolution is a process that has enabled marine mammals around the world to adapt to their surroundings and have a higher quality of life. For example, emperor penguins do not have all five standard taste buds due to their constant exposure to cold weather, but this is actually beneficial because it allows them to swallow fish whole on a regular basis without getting tired of continuously eating the same thing. Ultimately, each species on the planet evolves as needed for survival or it eventually becomes extinct, and there are many examples of marine mammals that have evolved in the Arctic and Antarctica regions.

Basic Evolutionary Patterns of Marine Mammals

Mammals such as whales that are found in the ocean can trace their family line back to ancestors that lived on land. In order to fit into their new environment, a long list of basic alterations has occurred over time. These changes are physical and behavioral, and they can be observed in each mammal species that expedition participants will encounter in areas such as the Arctic Ocean, Greenland and Antarctica.


The most noticeable physical changes include the streamlining of every marine mammal’s body. Each mammal used to have more noticeable ears, and their bodies also once contained hind limbs. Now whales and other marine mammals have small holes that they hear out of, and they have developed a cylindrical body type to improve their swimming ability and reduce heat loss.  


Swimming is considered to be the most vital behavioral change exhibited by marine mammals, and this required physical changes that allow each creature to receive enough oxygen. Sea otters take advantage of bradycardia to sustain their breathing through dives that can last as long as five minutes, and fin whales have the extraordinary ability to completely fill their lungs in only two seconds.

Sea Otters: An Intriguing Evolutionary Development

Some marine mammals are able to do things that are typically associated with humans, and these traits showcase an advanced level of evolution. Sea otters are often observed using makeshift tools, and this puts them in a rare class of mammals that have evolved in such a useful way. From a survival standpoint, it makes perfect sense for sea otters to have developed this ability because they use tools such as kelp strands in order to secure themselves into their surroundings before they go to sleep. This prevents them from drifting off, and it also makes it more difficult for their prey to quickly drag them away.  

Marine Mammals are Big and Getting Bigger

Bigger is definitely better in the case of many marine animals, according to a Stanford study that lit up the Internet like a Christmas tree last month. The Los Angeles Times reported that the Stanford scientists involved in the study extensively researched many types of marine animals that lived more than 550 million years ago to see how their body sizes evolved over time. Their findings? Although some of these creatures tended to get larger and others did not, the average body size of the majority of these creatures steadily increased 150-fold throughout history, and the evolutionary trend in marine mammals leaned toward larger-sized bodies.


The ones that did get larger became more diverse as time passed, too. They also tended to put on more weight, which led them to be more successful in their environments. These changes brought with them great speed, and you can marvel at how fast these bulky whales and other large marine mammals navigate through the ocean waves despite their size during expeditions. More importantly, seeing the majesty of these behemoths from the bow of a boat is a spiritual experience that can’t be duplicated on the television at home, no matter how big your widescreen TV is or how good the resolution is.

Who Were the Ancestors of Today’s Marine Mammals?

Research indicates that the very first mammals evolved approximately 200 million years ago, and they had to spend much of their life in hiding from dinosaurs. According to fossils that have been discovered, the earliest ancestors of what we now call whales first appeared about 10 million years after dinosaurs died out. In the 1800s, the bones of the land-dwelling ancestor were easily found in many areas of the U.S., and it became apparent from the teeth fossils that this creature was not a reptile. This creature became known as the Basilosaurus, and there was much debate about whether it was a dinosaur or the earliest link to whales. Fortunately, answers finally began to arrive in the 1980s, and we now know that there were many transitionary creatures between the Basilosaurus and the modern whale, including Pakicetus inachus and Indohyus.


Although scientists are still uncovering the exact origins of most marine mammals, you can gain a basic understanding of the evolutionary chain by considering how whales evolved from land-dwelling creatures 190 million years ago to the graceful and musical ocean dwellers that explorers of the Arctic and Antarctic love to see during modern expeditions.

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