Wildlife Champion
In our series about people with a passion for a species, we ask Australia’s popular scientist ‘Dr Karl’ why he cares so much about fin whales.
Why popular scientist ‘Dr Karl’ is in awe of the fin whale
Why have you championed the fin whale?
I love fin whales because they can double their own weight when they feed. A small individual ‘lunging’ on a school of krill can go from 60,000kg up to 130,000kg – so you’ve got a 6o,000kg whale taking on 70,000kg of water in just six to 10 seconds. A fin whale can consume up to 2,000kg of krill a day – which is amazing! It seems counterintuitive that the second largest whale in the ocean (growing up to 27 metres long and weighing as much as 120,000kg) feeds on tiny crustaceans.
Have you ever seen this behaviour?
Not yet. I’d love to watch a fin whale charge a school of krill and then, just before the whale is about to make contact, see it turn on its side and open its mouth – practically at a right angle to its body – as its smooth, streamlined shape transforms. The fin whale filters a huge volume of water using its baleen plates, trapping prey inside. During this action, its huge mouth reminds me of the folds of an accordion.
Describe your most thrilling whale encounter…
I’ve been to Antarctica three times. On one occasion I jumped into the Ross Sea, a deep bay in the Southern Ocean, when the temperature was -1.8°C (it hadn’t frozen because it was very salty). I just had my swimming costume on – no fancy thermal stuff – and a rope tied around my waist. Under the water I could hear whales making deep calls. After about 30 seconds I was pulled back to the boat and had the worst headache I’ve ever had in my life!
When did you learn about fin whales?
I’m a journalist with degrees in medicine and surgery, physics, mathematics and engineering. Each year, I read my way through $10,000 worth of science literature. In 2007, I came across the paper ‘Big gulps require high drag for fin whale lunge feeding’ in the Marine Ecology Progress Series, and that got me thinking about fin whales. I couldn’t work the information into a full story until this year. In March 2018, ‘Energetic tradeoffs control the size distribution of aquatic mammals’ was published in the Proceedings of the National Academy of Sciences, and I was able to come up with chapter 44, ‘Why Are Whales So Big?’, in my book Vital Science.
Why are whales so big?
They have to keep their body temperature at a fixed level, a process known as thermoregulation. If they don’t, the enzymes stop working properly and they die. Geometry tells us that bigger is better for maintaining body heat. The bigger a mammal is, the less surface area it has relative to its volume. This is important, as surface area is where heat is lost. So, if a mammal wants to survive in water, it need lots of volume but not too much surface area, and this is achieved by evolving to be bigger. Jo Price
A fin whale can consume up to 2,000kg of krill a day – which is amazing!