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MEPS prepress abstract   -  DOI:

Multi-cusped postcanine teeth are associated with zooplankton feeding in phocid seals

Uno Ishihara*, Nobuyuki Miyazaki, David Yurkowski, Yuuki Y. Watanabe

*Corresponding author:

ABSTRACT: Tooth morphologies often reflect diet in animals. Among marine mammals, a well-known example is krill-feeding crabeater seals (Lobodon carcinophaga), in which complex, comb-like postcanine teeth function as a sieve by retaining krill inside their mouth while expelling water. However, information on teeth morphology and function is scarce for other seal species. A recent bio-logging study found that Baikal seals (Pusa sibirica) feed on tiny pelagic amphipods at remarkably high rates with highly multi-cusped postcanine teeth, highlighting the need for comparative analyses on teeth morphologies and diets in phocid seals. Here, we quantified postcanine teeth morphology for 13 seal species based on museum skull specimens, with a particular focus on Baikal seals and their related species (genus Pusa and Phoca). The species in Pusa, including Baikal seals, had more specialized multi-cusped postcanine teeth than Phoca species, reflecting higher zooplankton proportions in their diets. Postcanine teeth of Baikal seals exhibited the highest degree of specialization among Pusa, even when the effect of age-related wear is controlled for. This result agrees with the highest zooplankton preference in this species. Further, we found a strong positive correlation between the degree of specialization in postcanine teeth and zooplankton reliance across phocid seal species. Our findings indicate that the functional role of multi-cusped postcanine teeth as a sieve is not limited to crabeater seals but prevails in many phocid seals feeding on zooplankton.