Revisiting the behavioural framework of feeding in predatory aquatic mammals

S. S. Kienle, C. J. Law, D. P. Costa, A. Berta, R. S. Mehta. Revisiting the behavioural framework of feeding in marine mammals. Proceedings of the Royal Society B 284: 20171035. (pdf)

ABSTRACT

Carnivorous mammals have converged on a handful of aquatic feeding strategies: biting, filter feeding and suction feeding (Taylor, 1987;Werth, 2000a;Hocking et al., 2017;Kienle et al., 2017). A biting feeding strategy is characterized by prey being seized by the jaws and/or teeth and is divided into three subcategories: crushing, grip and tear feeding, and pierce feeding. ...

... Pinnipeds (seals, sea lions and walruses) are one of the only marine mammal lineages to use all three aforementioned feeding strategies (King, 1983;Taylor, 1987;Werth, 2000a;Hocking et al., 2017;Kienle et al., 2017). The evolution of pinnipeds from terrestrial carnivores suggests that the ancestral feeding strategy is biting (Werth, 2000a), which is supported by the skull and dental morphologies of early pinnipedimorphs (extant pinnipeds and their fossil relatives; Adam and Berta, 2002;Churchill and Clementz, 2015). ...

... Some individual harbor, ringed and spotted seals made repeated ventral depression of the lower jaw and small dorso-ventral movements in the gular region after the prey was inside the mouth prior to swallowing. Similar behaviors have been described as chewing in subantarctic fur seals (Arctocephalus tropicalis), Australian fur seals (Arctocephalus pusillus doriferus) and Australian sea lions (Neophoca cinerea; Hocking et al., 2014Hocking et al., , 2015Hocking et al., , 2016, where chewing is defined as modifying prey using repetitive motions of the jaw/teeth to pierce, cut or crush items that are inside the mouth ( Hiiemae and Crompton, 1985;Reilly et al., 2001;Schwenk, 2000;Hocking et al., 2017;Kienle et al., 2017). In pinnipeds, chewing is separate from mastication because the teeth are not in occlusion (Adam and Berta, 2002;Berta et al., 2006;Hocking et al., 2015)