Dublin Zoo acquired an elephant seal in 1965. Its sojourn here, however, was not an entirely happy one. According to Catherine de Courcy, in her book , the new arrival seemed not to take to his new home. He went on strike for six weeks initially. Then he changed tack, opting for an opposite strategy; eating the Zoo out of house and home. He gorged himself on 30 kilograms of fish each day. Thankfully, An Bord Iascaigh Mhara came to the rescue, picking up the food tab for the expensive guest. In gratitude, the keepers named the seal ‘BIM’.
But Bim’s disenchantment continued. He wanted out, so he climbed over the one-metre high iron railing of his enclosure — a considerable feat for an awkward lumbering giant. He went walkabout until his keepers managed to coax him onto a tarpaulin and carry him back to his pool. Security was improved but, the following year, the Zoo was treated to Great Escape 2. This time, the renegade took refuge in the giraffe house. A mobile crane and a dump-truck were needed to recapture him. Bim died of heart failure in 1969.
Despite their name, elephant seals aren’t related to elephants. However, like the largest land mammal, they are the giants of the ‘pinniped’, the ‘fin-footed’, tribe. A ‘bull’ elephant seal can weight up to 4 tonnes and reach a length of 4 metres. Their huge size helps protect seals from hypothermia in the cold waters where they live. The prominent ‘nose’ may resemble an elephant’s multi-purpose Swiss-army-knife of a trunk, but its chief function is to amplify its owner’s roars during the annual rut.
Like their Irish cousins, elephant seals have short limbs and lack external ears. These adaptations reduce ‘drag’ when swimming, but there’s price to be paid for streamlining; seals must crawl on their bellies when on land. Moving even 10 metres is a challenge but, once back at sea, they can swim 100 kilometres in a day.
The fossil record is meagre, but a paper published in 2016 suggested that the elephant seal evolved in the southern hemisphere and eventually split into two populations isolated from each other. One became the Northern elephant seal, the other the Southern. Bim was a southerner.
The species’ rather tragic history mirrors Bim’s story but with a happier ending. Elephant seals were slaughtered mercilessly for their oil, both species being persecuted to the brink of extinction. The decline of the northern tribe has been particularly catastrophic.
New paper on the genetic and fitness consequences of an extreme bottleneck on northern elephant sealshttps://t.co/acuBRaf7z6
— Joe hoffman (@J_I_Hoffman) October 1, 2024
In a paper just published, Joseph Hoffman and colleagues, at Bielefeld University in Germany, say that “the population was likely reduced to fewer than 25 animals” at the start of the 20th century. Inbreeding still threatens its survival, but all is not lost. With the tender loving care of dedicated conservationists, numbers have risen to 225,000.
BIM’s relatives in the Southern Hemisphere also suffered greatly but “they did not experience such a drastic decline”, managing to retain some protective genetic traits which have been lost by their northern cousins.
