When is a seal not a true seal? When it’s an eared seal! So what’s the difference?
True seals (phocids) are unable to use their rear flippers for propulsion and thus generally move slowly and clumsily. They loll around on land yet swim with grace. The true seals I saw around the Antarctic Peninsula included the Weddell Seal, the Leopard Seal and the Southern Elephant Seal.
The Weddell Seal is marked with splotches and has a small round head. Females can grow up to 3.3 metres, with the male slightly smaller. Adept divers, Weddells can descend to 500 metres for 15 minutes or more in pursuit of fish and molluscs. As the most southerly breeding seal, Weddells survive winter by gnawing sea ice to keep airways open. In this way, the males attract the females by guarding their breathing holes. But this comes at the cost of wearing down their canines and incisors – once these teeth become so worn as to be useless, the old males die.
The female of the Leopard Seal (cow) is larger than the male (bull) and can grow up to 3.8 metres long. With their tiny eyes, sharp teeth and muscular body, they can be very intimidating, yet they are known more for being inquisitive rather than aggressive. Their main diet is fish, with a 20% supplement of penguin which has given them a bad reputation.
The Southern Elephant Seal is the largest of the seals, with old bulls growing up to 6.5 metres and weighing up to 3.7 tonnes. They move on land like giant caterpillars, but lie in rows like tinned sardines when going through their 3-week moult. The bulls have a long proboscis that grows with age which is inflated as a resonating chamber when roaring at a rival.
Eared seals (otariids), such as the Antarctic Fur Seal and Sea Lion, have very obvious ear flaps. They have long front flippers that can support their weight which enables them to move relatively quickly on land.
The Antarctic Fur Seal is much smaller than the true seals, with the males growing up to 2 metres long. They typically rest propped up on their fore flippers, with their breast, head and neck vertical. Fur seals swim by ‘porpoising’ like a penguin (or a porpoise!). Fur seals have a thick coat, rather than blubber, to keep them warm. Their fur consists of a soft undercoat with thick guard hairs.
Antarctic Fur Seal populations were greatly depleted from hunting during the late 1700s to the early 1900s, with hundreds of thousands being killed for their pelts to make hats and coats. In 1825, the British government introduced regulations to make the sealing industry more sustainable, and by the 1950s commercial fur sealing in the south had nearly ended. From rebounding to a population of 100,000 in 1976, the Antarctic Fur Seal population is now estimated to be between 2 and 5 million.
Southern Elephant Seals were also once the target of sealers. Their blubber was rendered to oil to be used in paint, soap and candles, until 1964 when the industry was no longer viable. In 1975, the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES) came into force, ensuring that wild animals and plants are no longer threatened by the commercial pressures of international trade. In 1978, seals received another layer of protection under the Convention for the Conservation of Antarctic Seals (CCAS), which sits within the Antarctic Treaty System. Under CCAS, no seals can be killed or captured for any purpose without government-issued permits.
However, seals face an uncertain future due to warming oceans, ocean acidification, increased plastic pollution and other threats, most of them caused by humans. One way to support Antarctic seals is to establish a network of marine protected areas (MPAs) across the Southern Ocean. MPAs are like national parks in the sea, where human activities are more strictly regulated than elsewhere.
You can find out more about Antarctic marine protected areas by visiting the Commission for the Conservation of Antarctic Marine Living Resources, The Pew Charitable Trusts and the Antarctic and Southern Ocean Coalition.