The path of whale evolution has involved the reduction or loss of several traits that are still prominent in most other mammals. TRUE (1) or FALSE (2). In terrestrial mammals, the sense of smell (olfaction) involves receptor proteins encoded by a number of genes. Whales don't have a sense of smell underwater, but their genomes still contain copies (pseudogenes) of some of these olfactory genes in their genomes. Because they are still present in whales' genomes, these genes must serve some other function in whales. Whales have some vestigial features like muscles that are attached to external ears in other mammals, even though whales have lost their external ears. Humans also lost some traits (e.g., body fur) and also have some vestigial traits, such as a mechanism to cause fur to stand on end even though we are mostly hairless (i.e., arrector pili muscles that produce goosebumps). Some features like hindlimb buds and whiskers are observed in whale embryos but these do not go on to form structures that are visible in adult whales. This suggests that the ancestors of whales had these traits, even though they've been lost in adult whales. If extinct whale species like Basilosaurus used their tiny hindlimbs in mating, then these were not vestigial limbs. Whales lost their hindlimbs and evolved a tail for swimming (called a fluke). Whales swim by undulating their fluke in an up and down motion, but they could have just as easily evolved a side-to-side swimming motion like the one seen in fishes
The path of whale evolution has involved the reduction or loss of several traits that are still prominent in most other mammals. TRUE (1) or FALSE (2).
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In terrestrial mammals, the sense of smell (olfaction) involves receptor proteins encoded by a number of genes. Whales don't have a sense of smell underwater, but their genomes still contain copies (pseudogenes) of some of these olfactory genes in their genomes. Because they are still present in whales' genomes, these genes must serve some other function in whales. |
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Whales have some vestigial features like muscles that are attached to external ears in other mammals, even though whales have lost their external ears. Humans also lost some traits (e.g., body fur) and also have some vestigial traits, such as a mechanism to cause fur to stand on end even though we are mostly hairless (i.e., arrector pili muscles that produce goosebumps). |
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Some features like hindlimb buds and whiskers are observed in whale embryos but these do not go on to form structures that are visible in adult whales. This suggests that the ancestors of whales had these traits, even though they've been lost in adult whales. |
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If extinct whale species like Basilosaurus used their tiny hindlimbs in mating, then these were not vestigial limbs. |
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Whales lost their hindlimbs and evolved a tail for swimming (called a fluke). Whales swim by undulating their fluke in an up and down motion, but they could have just as easily evolved a side-to-side swimming motion like the one seen in fishes. |
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