The evolution of whales is an interesting series of events. When you look at a whale, you initially would think that it had evolved in the water, living as an aquatic animal its entire life. This is not the case. Whales are a rare example of an animal that began as a terrestrial organism, and over time, transitioned back to the water.
Before you begin your research of the evidence of whale evolution, you should know some background information about whales.
Whales are from the order Cetacea, which includes all modern whales, dolphins, and porpoises. Cetaceans are mammals, which means they possess the following characteristics:
As you can see, these characteristics distinctly seperate whales from their other aquatic counterparts, fish. Because of these characteristics, along with a large amount of evidence, scientists have come to discover that whales descended from land mammals about 50 million years ago.
Whales are from the order Cetacea, which includes all modern whales, dolphins, and porpoises. Cetaceans are mammals, which means they possess the following characteristics:
- Vertebrae (spine and spinal cord)
- Ability to thermoregulate (warm-blooded)
- Live birth
- Produce milk to feed their young
- Hair on their bodies
- Breathing through lungs
As you can see, these characteristics distinctly seperate whales from their other aquatic counterparts, fish. Because of these characteristics, along with a large amount of evidence, scientists have come to discover that whales descended from land mammals about 50 million years ago.
So, what is a whale most closesly related to?
Cetaceans are not closely related to fish, or sharks, or most other aquatic animals. The animal that modern-day cetaceans are most related to are: hippos! This does not mean that whales are direct descedents of hippos. Rather, the hippo and whale are the closest living animals that have a common ancestor. Somewhere about 54 million years ago, an animal was the ancestor of both hippos and whales. Since then, their species broke off and evolved seperately. Today, hippos and whales are the closest living ancestors.
At this point, please move on to comparative anatomy to discover how scientists use the body parts of a whale to determine its ancestry, and how it is related to the modern day hippo.
