NATURAL WORLD FACTS
The Stages of Whale-Fall Ecosystems.
For the most part, the nutrients found in the depths are supplied by a steady steam of organic debris falling down from shallower waters. It's not much, but it tends to be enough to sustain the sparse and barren depths. But every now and then, something much larger sinks to the seabed. It draws life from miles around to gather for a feast to last for decades. It is known as a whale-fall.
Whale-fall ecosystems support an abundance of life in waves of successive communities. The carrion of the whale is first stripped of all its flesh by larger scavengers, like Greenland sharks. Once all the flesh is gone, and any debris in the sediment has been hoovered up by opportunists like ghost sharks, bacteria break down the bone lipids to produce energy that supports an ecosystem of life around the carcass.
It is thought that whale-falls may have been the crucial stepping stone that allowed deep-sea species to colonise the sea floor.
Occasionally, a whale carcass will sink to the seabed, and can support a complex biological community for up to 50 years.
Most nutrients in the deep sea are supplied by a steady stream of organic debris, known as marine snow.
Mobile scavenger stage
Lasts 4 months - 2 years
When the carcass comes to rest on the sea floor, the first organisms to arrive at the scene are 'mobile scavengers' - these are the larger ocean wanderers, including hagfishes and gigantic sleeper sharks. Whale-falls attract such an abundance of life because their nutrient content is equivalent to 2,000 years worth of marine snow, providing a rich supply of nutrients concentrated in one small area.
The flesh and soft tissue can support this community of scavengers for up to 2 years. After that time, all that's left are bones, and chunks of organic material buried in the sediment.
Hagfish
Myxini glutinosa
The hagfish makes use of four pairs of thin sensory tentacles around their mouths in order to seek out the whale carcass. Once there, they use two rows of sharp tooth-like structures to burrow down into the carcass. They are also able to tear off chunks and deliberately tie their long tails into knots. This increases the force of their bites by creating torque.
ENRICHMENT-OPPORTUNIST STAGE
Lasts around 2 years
In this 2nd phase of the whale-fall community, mollusks, worms and crustaceans feed on any blubber that remains. As whale-falls are so rare, nothing goes to waste, so the opportunists will spend 2 years burrowing into the surrounding sediment in search of leftovers.
