When surfacing to breathe calmly, what is the typical motion observed for a harbour porpoise?

Answer

It performs a gentle roll from beak to fluke, arching its back slightly

Harbour porpoises are known for a very gentle surfacing action, rolling through the water with minimal splashing, which results in only a small, slender profile, including the small dorsal fin, breaking the surface.

When surfacing to breathe calmly, what is the typical motion observed for a harbour porpoise?
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