Last week I gave you this mandible from the collections of the brilliant Trinity College Zoological Museum to try your hand at identifying:

It’s quite a distinctive jaw, so I wasn’t too surprised that many of you recognised it, but I was hoping the relatively small size might have caused a little confusion – after all, it’s from a juvenile.

The robust bone and undifferentiated teeth scream “marine mammal” and the scarcity of those large teeth and that long and well-fused mandibular symphysis (the bit at the front where the two halves of the mandible meet) mean that we’re dealing with something that has an unusual approach to eating.

As Wouter van Gestel, Richard Lawrence, Rémi and palfreyman1414 spotted, it’s the mandible of that infamous oyster (and clam) devourer, the Walrus Odobenus rosmarus (Linnaeus, 1758). I’ve talked about these huge pinnipeds on the blog before (many moons ago now) but since then we’ve learned more about how they feed.

One of the most interesting elements of their feeding, apart from the use of suction to remove the soft parts of molluscs from their shells, is the use of their front flippers to create a vortex in the water that keeps the sediment that gets disturbed by their snuffling hunt through the mud from impairing their ability to see. Useful if you want to avoid predators like Orcas.

You can get an idea of what this looks like in this video: