The complex ecosystems of whale falls support unique and intriguing life forms, writes Arghya Gupta
Last week the body of a humpback whale washed up on Sydney’s Newport Beach. Why it did so remains to be seen, but experts suggest that it was sickly or malnourished with a thinner layer of blubber than expected. The humpback was too weak and the strong swells of the ocean brought it in to the northern beaches of Sydney. After a couple of days when it wasn’t taken back with the tide, a chainsaw team was called in to cut it up, arguably wasting the perfect opportunity for an episode of popular anatomy show ‘Inside Nature’s Giants’ to be made. Our friend ended up as part of the Lucas Heights landfill site, but in any other case, you may just well be asking: what happens to whales when they die?
A lot of the time they end up on the plates of Japanese and Norwegian diners, at other times they get scavenged upon by fish and other sea creatures before the bone erodes away over a couple of years. Other times, when the water is deep enough for oxygen levels to be so sparse that aerobic interactions are at a bare minimum, whales with large enough surface areas sink to the bottom of the ocean and stay there. These carcasses are called ‘whale falls’.
Whale falls are a relatively new concept. Until recently, whale deaths in deep waters were presumed to follow much the same procedure of their shallower gravemates. It was only in 1987 that a deep sea submersible called Alvin, scouring the sea bed off the Californian coast, spotted something they presumed to be a dinosaur skeleton. On closer inspection, it was found to be the remains of a blue whale, with all its bones intact, as well as harbouring a forest of marine flora and fauna. Things which have been found to exist only at whale falls, and nowhere else, including a species of worm, the Osedax, which have no mouths or stomachs, but just an ability to burrow into the whale bones and feed off the bone marrow oils and fats.
In deep water, bacteria feed off the muscle cells and bone cells. In extremely deep water, the oxygen needed for the bacteria to function is not sufficient, and as a result, the damage and disintegration of bone seen in normal depth carcasses is skipped, and the carcass floats down to the sea bed, undamaged. There it gives rise to more than thirty of the aforementioned species which live solely on the chemicals in whale bones, and can possibly last for more than 100 years. Shipwrecks have also shown ecosystems of this sort, but they have been a recent phenomenon compared to the fossil record of whale falls suggesting they have existed for thousands of years.
But herein lays the problem of whale fall sightings. With the advent of whaling since the 1800s, the proportion of whales dying naturally in deep water have been significantly reduced.With most whale species now classified as endangered, the likelihood of humans coming across more whale falls is lower, especially given deep sea exploration is only slowly improving as an activity and research method. With fewer whale falls, there are likely to be fewer bizarre species inhabiting this planet. Indeed, they may have enzymes to prevent the progression of cancer, but more so, their reduction will mean some of the fascinating aspects of nature will be lost as more whales end up at Lucas Heights. If they die naturally however, there may be some cool Virgin concept allowing us to see firsthand perhaps some of the craziest things known to science.