Which specific feature, visible when surfacing in calm water, might confirm an observer is watching a dolphin instead of a harbour porpoise?
Answer
A tall, sickle-shaped dorsal fin
If the observed animal surfaces with a very tall, sickle-shaped (falcate) dorsal fin and a prominent beak, it is confidently identified as a dolphin, as the harbour porpoise lacks both of these features.
Related Questions
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