The Grey Seal
After a hundred years of absence from Danish waters, first of all, due to hunting, the Grey Seal has reintegrated over the past fifteen years and now occurs regularly in locations in the Baltic Sea, the Wadden Sea and the Kattegat. The Grey Seal now again breeds a few places along Danish desolated coasts.
Denmarks largest land-breeding predator.
The scientific name of the grey seal, Halichoerus grypus, is Latin for “hook-nosed”; males have large, arched snouts.
The Grey Seal is a large seal, with bulls in the eastern Atlantic populations reaching 2.5–3.3 m (8.2–10.8 ft) long and weighing 170–310 kg (370–680 lb); the cows are much smaller, typically 1.6–2.0 m (5.2–6.6 ft) long and 100–190 kg (220–420 lb) in weight. Individuals from the western Atlantic are often much larger, males reaching 400 kg (880 lb) and females weighing up to 250 kg (550 lb).
Danish scientists are familiar with examples that Grey seals have killed Harbour seals and eaten them. They are bigger and more aggressive. Some of them may even have specialized in Harbour seals and actually also on Harbour porpoises.
The origin of the mermaids
The view of a grey seal is that of a bobbing head as the seal rises out of the water for a look above the surface. At first glance seals adopting this behaviour look remarkably like people bobbing up and down in the water, a fact which undoubtedly contributed to legends of mermaids.
Source: dce.au.dk, jp.dk, NaturGuide.dk, irelandswildlife.com, Wikipedia.