 Deterioration of whale carcasses happens though a series of three stages . Initially , moving organisms such as sharks and hagfish , scavenge the soft tissues at a rapid rate over a period of months , and as long as two years . This is followed by the colonization of bones and surrounding sediments ( which contain organic matter ) by enrichment opportunists , such as crustaceans and polychaetes , throughout a period of years . Finally , <unk> bacteria reduce the bones releasing hydrogen sulphide enabling the growth of chemoautotrophic organisms , which in turn , support other organisms such as mussels , clams , limpets , and sea snails . This stage may last for decades and supports a rich assemblage of species , averaging 185 species per site . 
