In the next “Marine Mammal Highlights” section, we discuss our favorite pinnipeds – i.e. seals or sealions. The first pinniped we’ll discuss is the leopard seal, and Dr. Cindy Elliser explains below why she thinks it is the coolest one! (Psst don’t forget, you can watch all our “Marine Mammal Highlights” conversations on YouTube or listen to it on the “PacMam Podcast“!
Is this a seal, or a lizard in a seal’s fur? This may seem like a silly question – until you see a picture of this seal’s face! This animal, although it has spots like a leopard (hence the name leopard seal), has a more defining feature in my mind – how much their head looks like a reptile! It really looks like a giant (at 10-11.5 ft and up to 1000 lbs they are second largest seal) lizard or snake, covered in fur, with a very ferocious grin…what do you think?
And ferocious they are – they are the only seal that feeds regularly on warm-blooded prey (other seals eat fish, crustaceans and the like). With their canine teeth they prey on fish and squid, but also on penguins and even other seals! Now if that wasn’t strange enough, they also have tri-lobulated teeth that allow them to filter krill (small shrimp-like crustaceans that are more famously fed on by large baleen whales). This seal has one of the most wide ranging diets – rarely will you find a hunter like this that can also filter feed.
Perhaps these feeding strategies evolved because they live in remote and harsh environments – in the Antarctic and sub-Antarctic waters. You need to be able to get food wherever you can in places like that. They don’t dive as deep and long as other seals, because they don’t have to. They have figured out if they lie in wait by the ice shelf, they can grab penguins as they dive into the water to go on a foraging trip – imagine being a penguin and jumping into that fierce mouth! Or, you are a penguin ready to jump in and barreling out of the water, swimming at up to 25 mph, launches a leopard seal onto the ice to grab you – that is a terrifying sight! Once caught the seal will actually skin the penguin by shaking the bird until the skin tears away – I guess they don’t want to fill up on feathers. Leopard seals are quite intelligent too – they have been documented playing a cat and mouse game with penguins by cutting off their routes back to shore. Researchers don’t know why they do this. Perhaps for fun, or perhaps that is experience as they learn to hunt. Either way, not fun for the penguins. Now what eats them? Not much. Killer whales are the only ones documented that have eaten them, though it is thought that sharks likely do as well. They haven’t been hunted for their fur by humans like other seals have, again because it isn’t so easy to get where they are – not worth the danger of the trip to try and get there. During the austral fall and winter they will move north seasonally, coming to South Africa and South Australian coasts around Tasmania, New Zealand, Lord Howe Island, Cook Islands and Tierra del Fuego.
Now New Zealand is unique – there is a resident population that resides there year round that has recently been documented through photo-identification by our colleague Dr. Krista Hupman at www.leopardseals.org. To learn more about these seals that have decided New Zealand is a better place to hang out than the Antarctic, they collect scat (poop). You can tell a lot about the diet and health of a species through their poop. The researchers recruit volunteers to collect and send in scat. In 2017 a volunteer picked up some scat and sent it in. It was frozen until it could be analyzed and in 2019 they took it out and found a USB stick (in the poop, not with the poop, it definitely had been eaten)! They cleaned it off and it still worked! It had vacation photos on it – which they posted to social media and quickly found the owner. Now this USB stick was dropped, eaten by a leopard seal, pooped out, frozen for 2 years, and STILL WORKED! Perhaps that company should have the leopard seal on their advertisements, that is one hardy USB. You can read an article about this here!
We don’t know a great deal about this species due to its location, so we are limited in the details of their lives. But we do know that they mate in the water, unlike other Antarctic seals, but pup and nurse on the ice. Males have distinctive stylized calls. They sing, similar to how humpback whales do it, hanging upside down and rocking side to side in the water. This is thought to be breeding behavior. Like other seals and sea lions after mating they delay implantation of the fertilized egg, in their case for 2 months. Their gestation lasts 11 months and they give birth in November and nurse their young for one month.
Now, we have talked about what fierce predators they are, and they may look scary, but that isn’t all there is to them. They aren’t super aggressive, at least to people. There has only been one documented human death by a leopard seal, and that was a researcher that was snorkeling in Antarctic waters and got pulled under by the seal. One individual seal even tried to give food to a person! Paul Nicklen, a famous wildlife photographer, was in the water taking pictures and a female leopard seal kept bringing him live and dead penguins. Paul thought that the seal viewed him as a useless predator and was attempting to help him learn to hunt. Almost like, oh you poor thing, let me help you, you won’t survive up here if I don’t!
So there you have it, the leopard seal that looks like a reptile in seal’s fur. There are many cool facts about these guys, it is hard to say that one is more interesting than the other. But one thing remains – we don’t know enough, and more research is needed! Thank goodness we have our friends and colleagues down in New Zealand working hard to try and understand this enigmatic, fierce, but beautiful species.