St-Lawrence Golf • Magdalen Island
© Mario Cyr
Adult males are 2.6 metres (8 ft 6 in) long on average, and weigh 300–410 kg (660–900 lb). Sexual dimorphism is obvious from birth and females are much smaller: 2.03 metres (6 ft 8 in) long and weighing 145–300 kg (320–660 lb). The colour is silvery; the body is scattered with dark, irregular marks. The bulge develops when the seal is four years old. The male can blow up this bulge, so that it is the size of its head.