Most people are familiar with this term, it refers to a layer of fat that is unique to marine mammals that enables them to survive in cold water! Find out more in our latest Wildlife Officer blog.
White-beaked dolphins are known as a sub-polar species, meaning they like to hang about in areas where it’s pretty chilly for most of the year. They are large, chunky dolphins that are adapted to living in cold temperate waters, reaching three meters long and weighing 350kg (55stone/ 771lbs). Apart from a resident pod that live in Lyme bay, Dorset, they are usually seen in the North Sea, the North Atlantic, and the cold continental shelf waters of Scotland, which is exactly where I saw them, having a gentle swim a few miles off the Isle of Lewis coastline.
I was pretty chuffed that my first cetacean encounter of the season was with a species that was new to me. That is probably why I didn’t have a clue what I was seeing at first and I had to record them in my survey as ‘Unidentified dolphins’. It wasn’t until later when I studied my blurry distant photograph that I realised they were white-beaked dolphins, and my heart did a few summersaults at first because I mistook them for killer whales.
You can see how a white-beaked dolphin could be mistaken for a killer whale, they are robust black and white dolphins with a large dorsal fin, and it can be hard to get a sense of scale when you are a fair distance from them.
It was a beautifully warm sunny calm day on my crossing from Ullapool to Stornoway. In all the guide books, white-beaked dolphins are described as fast swimming energetic dolphins, but on this day they were taking a slow leisurely swim. ‘They must be enjoying the warm weather’ I thought to myself, but then I remembered that despite the sunshine, they were swimming in water that was less than eight degrees at this time of year. How on earth are they able to, not just survive, but thrive in those constantly cold temperatures?! Especially when they are warm-blooded mammals. The main answer is blubber.
What is blubber?
Most people are familiar with the term blubber, it refers to a layer of fat that is unique to marine mammals that enables them to survive in cold water. Sounds simple enough, but blubber is actually amazing and it’s so much more than just fat. It insulates the animals, helps with their buoyancy, stores energy, and changes to suit the surrounding environment.
Some marine mammals have more blubber than others, especially Antarctic and Arctic species such as the bowhead whale, their blubber can be almost half a meter thick! In cold water, the blood vessels in the blubber shrink to reduce the flow of blood to the outside of the body. This reduces the energy needed to heat the body, conserving heat and energy for the cetacean (whale, dolphin or porpoise) and enabling them to function and appear perfectly relaxed in a temperature we humans just couldn’t handle. The blood vessels in the blubber can expand if the sea gets warmer, allowing blood flow to the outside of the mammals bodies to release heat. However certain species, being cold-water specialists, can only do this to a certain point. As seas warm due to climate change and global warming, many northern species are pushed further north to avoid warm waters that they physically aren’t equipped to deal with. Cetaceans can also experience bad sunburn if they become stranded as their skin isn’t adapted for long contact with sun rays.
Blubber is less dense than the water around it, meaning the animals will naturally float and have to put more effort into diving deeper than when swimming up to the surface. Handy when you are an air-breathing mammal who has to take a breath every so often. Many species of cetacean will rest and sleep at or near the surface, and being buoyant makes that much easier for them.
The energy stored in blubber includes both proteins (mostly collagen) and fats (mostly lipids). The ability of blubber to use these stored nutrients means marine mammals are not forced to search for food for long periods of time. Nursing mothers, for instance, build up thick stores of blubber before giving birth. In addition to feeding offspring, mothers cannot regularly search for food themselves, instead, they rely on the energy stored in their blubber. This means some species can travel huge distances on their migration without eating and some won’t eat at all during the breeding season. It is also thought that whales and dolphin’s physical ability to store energy for a long time has also enabled them to become so socially and emotionally advanced, having time to socialise, learn, and explore rather than constantly looking for food like small mammals who burn through energy quickly.
And another thing!
Another really interesting thing about blubber is that not only does it store energy, it also can store chemicals that have built up in the cetacean’s body over time, through what they eat and also the environment around them. Taking a sample of blubber from cetacean stranding events can give an indication of the health of that animal and even suggest how it came to be stranded by looking at the chemicals (some natural, some not) in their blubber.
The sea around the Hebrides never reaches above 20 degrees and so it’s suggested that swimmers should wear wetsuits to help them handle the cold. In a way, wearing a wet suit gives you some idea of what it’s like to have a layer of blubber, it’s certainly not as complex as blubber, but it takes the brunt of the freezing temperatures and leaves you feeling (slightly) protected.
Here’s me channelling my inner white-beaked dolphin in the sea on the Isle of Skye last week, before I heard about the wetsuit rule. This was genuinely unpleasant and my dip lasted about five minutes, illustrating how we land mammals just aren’t built for a life in the northern seas.
In my second month as the Hebrides Wildlife Officer, I have been on three ferry crossings with CalMac Ferries. My other two trips were to the Isle of Harris and North Uist, and to the Small Isles, where there were some atmospheric grey skies and choppy water, and not a high chance of seeing any marine mammals. I did see some cracking seabirds though, more incredible species with fascinating adaptions for an ocean life which will definitely need a whole blog of their own. Next month I will be able to tell you about my crossings to Tiree, Coll, Barra, and the Isle of Bute.
A grey and atmospheric Isle of Rum, taken from the MV Lochnevis.
Part of me wishes I had a layer of blubber, then I could float in the sea for hours looking at plants and creatures without getting cold, and think how much more I could do if I didn’t have to stop and eat every few hours. Who would have thought a fleeting encounter with two chilled out white-beaked dolphins would give me a newfound interest in blubber! And a new appreciation for our chunky cold water species. That’s the best thing about seeing these animals in the flesh and experiencing a moment with wildlife. The way they live and survive makes you think about your own life and the niche you are adapted for. It encourages you to take an active interest in their lives, discovering cool facts about them and yet more reasons why we should take pride in them and protect them. Ultimately when you see them you feel a connection to them. There’s a brief moment where they jump, breach, log, swim, or simply float from their world into yours, and it’s exhilarating.
I am so excited that from next week I will be able to actively engage with passengers (with masks and from a distance) and help them to have moments like this that leave you feeling a connection to nature, asking questions, and seeking to learn more about the incredible ocean wildlife that we have here in the UK.