Getting to know Antarctic seals
Seals, scientifically known as pinnipeds, are an incredibly varied and interesting groups of mammals. They are closely related to dogs, bears and otters and many things about them do remind me of my dogs back home.
I have had some opportunities to investigate the genetic diversity of pinnipeds, although currently in Colombia we don’t have any extant pinniped species. In the 1950´s, the Caribbean monk seal (Monachus tropicalis) was last reported close to San Andres and Providencia Islands in the Caribbean off Colombia. Since then, this species was declared extinct.
Seeing so many different seal species on this trip has been fascinating. I must confess that in this trip I fell in love with leopard seals (Hydrurga leptonyx). We have had the opportunity to work on genetics of these seals recently in collaboration with our colleagues from the Argentinian Antarctic Institute. Surprisingly, samples labelled as Weddell seals were in reality samples from this particular species. In this study, we found very high mitochondrial genetic diversity in leopard seals, and almost each individual sample had a unique mitochondrial DNA sequence or haplotype. This result can be related with the fact that these seals are solitary and pagophylic, meaning that they prefer living in the floating ice, travelling hundreds of kilometers in relatively short times. Leopard seals are imposing, big animals with a reptilian look and a big mouth, that can be extremely curious. We had a few checking us out and coming very close to the zodiac. Hopefully one day we may be able to sample them in a safe way, without risking a big bite.
In the laboratory we have also analyzed samples from southern elephant seals (Mirounga leonina). This is the biggest seal species in Antarctic and the Subantarctic Islands, with males reaching lengths of 6.5 m and more than 3000 Kg. The males have a characteristic long nose and they have big harems of females. We have found smaller groups in South Georgia with females and young males that are starting to grow their nose. Most of them are currently molting, meaning there are changing their skin and hair, getting ready to go back to the sea before the next breeding season during the spring and summer.
We also saw playful crabeater seals (Lobodon carcinophaga), chocolate in color and with a pointy nose. They are common to the South of Antarctic Peninsula, we saw them in Port Charcot, and close to the Antarctic Polar Circle. They are also pagophylic, preferring the floating ice to have their naps. We also saw Weddell seals (Leptonychotes weddelli) with their rotund body and a bit of a “catlike” face. Our last day in Antarctica, at Deception island, we saw one that was been picked on by Antarctic fur seals.
Antarctic fur seals (Arctocephalus gazella) deserve their own separate paragraph! We saw lots of pups and females in South Georgia during our first trip, which is currently their main breeding ground with more than 95% of the population inhabiting this island. The pups reminded me of little puppy dogs running up and down the beach, with one female trying to keep them a bit under control! Some of them can be a bit vicious, trying to attack and bite your legs if coming too close. But, most of them go back on their attack intention if they hear a strong STOP!
Where were the dads of all these pups?
During the second trip we found them in Wilhelmina Bay (Antarctic Peninsula), and in Deception island (South Shetlands).