Analogy: Jaws versus Flipper
Although their differences are certainly substantial (e.g., sharks are cold-blooded
and dolphins are warm-blooded), sharks and dolphins have some undeniable similarities:
side fins, a dorsal fin, and a torpedo-shaped body. These similarities are analogies
traits the two lineages evolved independently as adaptations for moving swiftly
in the water. Sharks were gliding through the oceans long before dolphins descended from
land-dwelling mammals. Dolphins evolved flippers, a dorsal fin, and a torpedo-shaped body
as natural selection shaped them for the life of an ocean predator.