<P> Finally "sulfophilic bacteria" anaerobically break down the lipids embedded in the bones . Instead of oxygen, they reduce dissolved sulfate SO and excrete hydrogen sulfide . Due to the toxicity of H S, only resistant chemosynthetic bacteria survive . The bacterial mats provide nourishment for mussels, clams, limpets and sea snails . As whale bones are rich in lipids, representing 4--6% of its body weight, the final digestion stage can last between 50 and possibly 100 years . </P> <P> A process called methanogenesis can also occur around whale falls . Archaea that produce methane can be abundant in anoxic sediment, but is typically not found in co-occurrence with the sulfur reducing bacteria found at whale falls . Whale falls do however support both sulfur reducing bacteria and methane producing archaea, leading to the conclusion that the area is not electron donor limited, and / or there is minimal or no competition for suitable substrate . Concentration gradients of both sulfide and methane can be found around whale falls, with the highest concentration coming within one meter of the carcass, which is several orders of magnitude higher than the surrounding sediment concentrations . Methanogenesis appears to only occur in sediments as opposed to sulfur reduction, which occurs both in sediments and on the bones of the carcass . The addition of sulfur reduction in both sediments and high lipid whale bones is a key factor for why whale falls are able to sustain deep - sea communities for extended periods of time . </P> <P> The differences in stage patterns between whale falls is likely to be related to carcass size . Large, intact whale falls appear to pass through the three decomposition stages, while the stages on smaller or partial carcasses may be truncated . Researchers believe the presence of 1 cm (0.39 in) Osedax (Latin: bone - devourer) may be a contributing factor in the successional differences . Also known as zombie worms--so called because they have no eyes or mouth--they were first discovered in the deep Submarine Monterey Canyon off central California in 2002 . Other examples have since been discovered off Sweden, Japan, and Antarctica . Osedax larvae have no digestive tract; instead they float through the oceans until they encounter a carcass . The worms then grow appendages resembling tiny trees that absorb oxygen . A root - like structure grows into the bone; these contain symbiotic bacteria which make an acid that breaks down proteins within the bone . The process supplies nutrients for the worms . When these worms sexually mature, eggs are released to start the cycle over . </P> <P> In 1989, scientists hypothesized that some species (such as Osedax) might use whale falls as stepping - stones to extend their range across multiple chemosynthetic communities . They estimate that 690,000 carcasses / skeletons of the nine largest whale species are in one of the three stages at any one time . This estimate implies an average spacing of 12 km (7.5 mi) and as little as 5 km (3.1 mi) along migration routes . They hypothesize that this distance is short enough to allow larvae to disperse / migrate from one to another . </P>

How long does it take for a whale to sink