Walrus an unusual visitor

THE Irish Sea has some unusual visitors this summer.

Normally, only porpoises are seen from the shore with bottle-nosed and common dolphins a bit further out. Minke whales, although common off the west, rarely visit the east coast. This year, however, the Irish Whale and Dolphin Group (IWDG) recorded minkes close to Dublin. On June 17, a fin whale was seen 14km off Howth Head, the only record for the Irish Sea since 2005. Then, on June 23, the IWDG received a call from a member of the public, John Byrne, about a creature he saw swimming at Magherabeg Beach, County Wicklow. The animal, too big to be a seal, was ‘reddish-brown with a lot of facial hair’. Only one sea mammal is prone to blushing, so Padraig Whooley of the IWDG concluded that the creature ‘may well be a walrus’.

This species is relatively new to Ireland; an animal on the Shannon in 1897 provided the first record. There were no further sightings until the 1980s, but there have been over 20 since then. Two carcasses were washed ashore, removing any lingering doubts that these Arctic-dwellers occasionally visit us. In April 1999, a walrus came ashore at Clew Bay and, in October 2004, surfers watched a ‘tan-coloured cow-sized animal’ exit the sea there.

’Walrus’ is one of the few Dutch words to find its way into English; ‘walvis’ means ‘whale’ and ‘ros’ means ‘horse’. This, the world’s weirdest sea-mammal, is such an oddity that zoologists have difficulty classifying it. Its closest living relatives are the seals and sea-lions. These were thought to have a common marine ancestor, but now it’s believed they evolved independently from otter-like creatures.

The walrus adds to the evolutionary conundrum; it has features peculiar to both. Like seals, it lacks ear flaps but it can move its hind flippers forward the way sea-lions do when they shuffle about on land. Walrus’ maternal behaviour is also different. Baby seals are weaned in less then six weeks, but a walrus baby suckles for a year and a half. Nor are twin tusks, the animal’s most striking feature, found in other sea mammals.

A large bull might weigh up to two tonnes, six times the weight of a grey seal and more than twice that of the largest European land animal, the elk. Bulk gives protection from the cold and walruses live in some of the coldest seas on Earth. Being heavy is not a burden when the creature is in the water and effectively weightless, but hauling itself out onto land or ice requires great effort.

We humans turn red when we’re ‘hot under the collar’, but a blushing walrus isn’t embarrassed or angry; it’s actually cooling down. The animal wears a wetsuit, a layer of blubber, 15cm thick, highly effective when diving but much too heavy when on land. But this is no ordinary suit; the blubber has channels running through it. These can open, bringing hot blood out to the skin, helping to reduce body temperature. Once back in the water, the blood vessels close and the animal turns from red almost to white.

Air travellers wear inflatable rubber pillows around their necks to help them sleep during long-haul flights. Walruses have a similar contraption, balloons on the sides of the head are filled with air from the lungs, forming a lifejacket. The wearer can sleep while afloat.

The function of the formidable tusks, is less clear. Like those of elephants, they are oversized upper canine teeth. Pointing downwards and curved towards the animal’s body, they seem awkwardly placed as defensive weapons. Nor are they used to rake the sea-bottom in the search of clams, the walrus’s favourite food, as was once thought. Walruses have a much more elegant approach to food gathering. They squirt jets of water to dislodge silt and expose the molluscs. It’s dark down there, but the sensitive whiskers of the walrus’ snout soon locate the prey.

The tusks, it seems, are more like the ice-picks mountaineers use. They can be driven into ice faces or hooked over a ledge, helping the walrus to climb out of the water. The males with the biggest tusks get the lion’s share of the females.

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