Tooth and Claw

How does a seal capture and eat it’s prey in the water?

Several people and institutions came together to investigate this question and explore the evolution of prey processing behaviors in phocine (seals) and otariid (sea lions). This collaborative work included researchers from Monash University in Australia, University of St. Andrews in the UK, Museum of Victoria, Australia, Australian museum of research institute and the ASLC.

The ASLC collected and contributed numerous video clips and photos of multiple prey processing events from our captive harbor seals, (Kordelia and Snapper):

Video from: https://vimeo.com/260181944

One key component of this study was to compare x-rays from phocine and otariids to a reconstructed skeleton of an ancient seal. This allowed researchers to elucidate the fore-flipper’s role in processing dead prey items in species whose foraging strategy has evolved  between terrestrial and aquatic environments.  The ASLC provided radiograph images, numerous photos and videos of prey processing behavior in our resident harbor seals..

F1.medium
Figure 1. From Hocking et al. 2018–Rather than bearing typical flippers like those of otariids (a), phocine seals have paw-like forelimbs with distinct digits and robust claws (b). (a,b) External forelimb anatomy for otariids (male Australian sea lion Neophoca cinerea) and phocines (female harbour seal Phoca vitulina—PV11). (c,d) Skeletal anatomy of the forelimb in otariids (long-nosed fur seal Arctocephalus forsteri—mirrored) and phocines (juvenile harbour seal). The radiograph image in (d) was taken under the Alaska SeaLife Center’s NOAA/NMFS Stranding Agreement. (e) Harbour seal (PV11) showing webbing between spread digits during swimming. (f) Harbour seal (PV11) showing distinct and mobile digits with strong claws.

You can learn more about how this study helps us understand how seals adapted to life in the water by checking out these amazing articles in:

The Conversation

Science Magazine

or read the scientific paper–hot off the press and open access:

Hocking DP, Marx FG, Sattler R, Harris RN, Pollock TI, Sorrell KJ, Fitzgerald EMG, McCurry MR, Evans AR. 2018. Clawed forelimbs allow northern seals to eat like their ancient ancestors. The Royal Society Open Science, DOI: 10.1098/rsos.172393

Written by: Renae Sattler

Featured Image Credit: Renae Sattler, ASLC

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