Final answer:
The "crabeater" seal is an aquatic mammal that eats mainly krill. Polar bears would be most impacted by the melting sea ice in Alaska. The evolutionary biology of species like sharks, lancelets, and aquatic mammals such as Rodhocetus reveals distinct habitats, lifestyles, and adaptations from land ancestors.
Step-by-step explanation:
Lobodon carcinophagus, known as the "crabeater" seal, is an aquatic mammal that primarily consumes krill, despite its misleading common name. Therefore, the correct answer to the question is: a) Seal.
Regarding the impact of sea ice melting in Alaska, the most affected animal would be the polar bear as they rely heavily on sea ice for hunting seals. On the other hand, grizzly bears, black bears, and koalas (which are not native to Alaska) do not depend on sea ice for their survival and feeding habits.
In evolutionary biology, it's important to consider how species, such as sharks and lancelets or lizards and whales, branch off and diverge from common ancestors. Although they may share certain structures like skeletons, their habitats and lifestyles differ significantly due to evolutionary paths.
Understanding the evolutionary history of aquatic mammals like Rodhocetus can provide insights into how certain structures, such as ankle bones, have adapted from land-dwelling ancestors. This is supported by the fossil record, which links aquatic mammals closely to specific groups of land animals.