Baird's Beaked Whales © Graeme Cresswell

The beaked whales are one of the most specialised and least understood of all the mammal groups. The world they inhabit is at the edge of our understanding, even in the 21st century it remains almost universally beyond our reach. To try and picture the world of a beaked whale imagine yourself sat in a hot air balloon a kilometre or two high. This is where you get the air to breathe. Below you the air is wrong - try to breath and you would suffocate and die, but the food you need survive is down there, 900 meters below. The only option is to take a deep breath and descend, tie a rope around you waist so you can come back up, then jump over the side and drop.

By the time you get to the bottom its dark; even if it is bright as a sunny summer’s day at the balloon above, it’s dark as a cloudy winter’s night down here, and its freezing cold. Now that you’re here there’s no time to waste, its time find food. But there’s a problem - in this darkness vision is useless and with food spread out touch wont help much either. So, you use sound. Projecting a beam of sound ahead of you like a torch you set off into the darkness, waiting for an echo, an object in the dark. Still holding your breath?

Cuviers Beaked Whale © Graeme Cresswell
This isn’t an empty landscape; you’re in a deep valley or hovering off the edge of a cliff. This is where food is most abundant, concentrated by currents and physical barriers, but the food won’t come to you, you have to go find it. So you search, casting your torch beam around. When you illuminate that object you then have to decide what it is, dinner or danger? If it’s the former, you still have to catch it. You don’t eat food that stands still, but rather fish and squid which can fly through these dark depths with all the speed, skill and control of swifts and swallows, and if your target gets out of your torch beam of sound you’ve lost it. When you find something edible you have to chase it down. Sometimes you miss but other times you catch your prey, but not using your hands (you don’t have any) or your teeth (even if you have them they are no use in feeding) but by sucking. You’ve come all this way to suck your dinner, which means you only eat food that’s small enough to succumb to the power of your throat muscles, and one meal is not enough you need to feed again and again each dive. Still holding your breath?

For an hour or more you carry on this cat and mouse chase through the permanent darkness, but eventually you do need air again, so you start to climb back up your rope. Remember the breathable air is 900 meters above you - just to breath again you need to climb a mountain. When you reach the safety of the balloon you can breathe, refuel your lungs, maybe socialise for a bit, but when you’re hungry there is only one place to get food and you have to drop again into the depths.

That’s something like the world of a beaked whale, that’s what it means to be a member of one of the most specialised families of mammals in the world. Of course the balloon isn’t a balloon, it’s just the surface of the sea and the hunting ground far below is underwater, the ocean floor - so far down that the human body would be crushed instantly by a pressure - 102 kg pressing down on every cm2 of your body. Next time you are in a supermarket pick up a kilogram of sugar (roughly two pounds) and think about that!

Strap-toothed Beaked Whale
© Simon Mustoe

To cope with this lifestyle the beaked whales have evolved a whole suite of specialisms. Some they share with other deep diving species - lungs that crush almost completely on diving, blood designed to carry enhanced amounts of oxygen around the body, a circulation system that isolates organs that aren’t needed at depth so that oxygen can be rationed and behaviours to mitigate for the debilitating effects of the bends. We know of some other weird and wonderful adaptations such as a specialised throat structure to allow strong sucking, teeth that are good for fighting over mates but nothing else, and pockets to tuck flippers into to swim more efficiently, others we can only guess at. Why have the densest bones of any mammal? Why have 13 stomachs?

Whatever the purpose of these adaptations, they work. With 21 species described to date the beaked whales are one of the most species rich cetacean groups, found from the equator to the edge of the pack ice. Some species are social, some loners, some resident, some migrants, some distantly related species appear so similar we can only safely separate them by their DNA, some closely related species are so different they can be told apart at a glance, some species carry the scars of fighting with them as a badge, some are unknown to science but for a couple of beach washed skulls. All however, are inhabitants of the deep waters of the open ocean, a world at the edge of our understanding but not immune from our impacts.

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