Whales have small, shrunken hip bones that do not connect to an actual leg or appendage sticking out of the body. What is the purpose of these hip bones? • A. None of these. • B. They no longer have a purpose but indicate whales evolved from 4 legged animals. • C. They are used to help the whale keep its balance
The Correct Answer and Explanation is :
The correct answer is:
B. They no longer have a purpose but indicate whales evolved from 4-legged animals.
Explanation:
Whales are mammals that evolved from land-dwelling ancestors with four legs. The small, shrunken hip bones present in modern whales, also called vestigial structures, are remnants of their evolutionary history. These bones are not connected to any functional appendages, such as legs, and they no longer play a role in locomotion or weight-bearing. However, they serve as evidence of the whales’ evolutionary transition from terrestrial to fully aquatic life.
Millions of years ago, the ancestors of modern whales were terrestrial mammals that used four limbs for walking. Over time, as these animals adapted to aquatic environments, their bodies underwent significant changes. Their hind limbs gradually disappeared because they were no longer useful in swimming, a process driven by natural selection. The hip bones became reduced in size and were repurposed in some ways for other functions, such as supporting reproductive organs. For example, in male whales, these bones help anchor muscles that control the movement of the penis.
Despite their reduced role in modern whales, these bones provide crucial insights into their ancestry. Paleontologists and evolutionary biologists have studied the fossil record to trace the transformation from terrestrial mammals, such as Pakicetus and Ambulocetus, to modern cetaceans like whales and dolphins. This evolutionary transition is considered one of the most compelling examples of how species adapt to new environments over millions of years.
In summary, while the hip bones in whales no longer serve their original function of supporting hind limbs, they are an important evolutionary relic. Their presence confirms that whales evolved from land-dwelling, four-legged mammals, highlighting the power of evolutionary processes in shaping the anatomy of living organisms.