Misstep this quick vault
Trade wade for flight; breath for salt
Soft doom, triple bloom
Given the biomass-dense, highly food-competitive environment of the ocean, it's not surprising that little food falls to the deepest places of the ocean floor. If it dies too deep for the pelicans to dive for it, and the tuna don't snap it up, and the sharks are busy chasing chum, there are hundreds of other hungry, squiggling species somewhere below, eagerly awaiting the scraps. By the time you reach the bottom, most everything that can be eaten has been eaten.
But two types of edible matter tend to make it down to the depths. The first is called marine snow, and is an accumulation of detrius so small that it has passed the notice of everything above. You can think of it as dandruff of the sea, and yes, animals have evolved specifically to eat this stuff.
The other is whalefall (also written whale-fall and whale fall.) Undernourished whales are so massive and less bouyant than their healthier counterparts, that when they die in the open waters and begin their epochal plummet, nothing has the time to really pick it clean before it's out of reach. So when the corpse finally comes to rest in the deep seas, it brings with it the equivalent of thousands of years of marine snow.
Understandably, entire ecosystems consisting of hundreds of animals have sprung up around these convenience stores of the deep seas.
Mobile Scavenger Stage
In the first stage mobile
scavengers come and chomp up whatever they can, reducing the corpse to scraps and bone in a matter of months. These species are not whalefall specialists.
Enrichment Opportunist Stage
Within a year the bones and nearby dandruff is infested with
worms,
mollusks,
crustaceans, and other
invertebrates with an amazing density--higher than any single other location in the deep sea--all relying on the food-web that results from direct digestion of the remaining organic matter.
Sulphophillic Stage
Within a year or two most of the digestible matter is gone.
Sulphur-reducing bacteria are still hard at work in the bones, though, and they give rise to the sulphur-loving wave of feeders, a wildly diverse group of life independent of the photosynthesis-web. This wave includes
bacteria, animalia that eat the bacteria, and strange creatures like
Osedax, who symbiotically harbor such bacteria within themselves as a means of digestion.
This is the longest wave, with communities of animals lasting, in one noted case, up to 50 years on a single carcass. The constituents of these food-webs overlap those of hydrothermal vents and cold seeps by only 10 and 20 percent respectively. The rest of the species found here are unique to whalefalls.
Redeath
When at last all edible matter has been consumed, the colonies depending on it die off. Part of their reproductive challange is to have cast off enough offspring to act as "nets" to catch the next whalefall. Estimates point (surprisingly, to the sound of the source articles) at an average of one whalefall every 5 to 16 kilometers off of the
Pacific Coast of
North America.
Other known whalefalls are known to occur in the trenches along the eastern and western borders of the Ring of Fire surrounding the Pacific tectonic plate (specifically the San Andreas fault, the East Pacific Rise, Bouganville Trench, Tonga Trench, Mariana Trench, and Kuril Trench), along the edge where the African and Carribean tectonic plates meet, Hawaii, and at the point way off of Madagascar where the Australian, African, and Antarctic plates meet. These mounds of foodstuffs have led at least one scientist to describe them as stepping-stones for faunal dispersal between distant hydrothermal vents and cold seeps.
Sources:
http://www.mbari.org/news/news_releases/2004/whalefall.html
http://www.mbari.org/news/news_releases/2002/dec20_whalefall.html
http://www.soest.hawaii.edu/oceanography/courses_html/OCN201/Smith/whalesS2004.pdf