Thursday, February 09, 2006
101 USES FOR A DEAD WHALE
Forget the Japanese and their "whale science". This man has it right. Craig Smith is a marine biologist at the University of Hawaii at Manoa.
Since 1992, he has been putting scrap metal on dead whales and sending them to the bottom of the ocean. He's done this with seven whales so far.
Smith and Amy Baco-Taylor of Woods Hole Oceanographic Inst. have estimated that 69,000 great whales die every year from disease and malnutrition and sink. The water pressure below about 1000 metres crushes the decomposition gases so they stay down. They also estimate that at any one time there are more than 850,000 whale falls on an average 12 kilometres apart.
Smith has been studying whale falls since 1998 including the ones he has sunk. A whale fall is a nutrient bonanza to over 40 species of deep sea life. In 1998, Smith sank a 35 tonne grey whale which was stripped to the bone in a year and a half. He estimates a large 160 tonne blue whale (pictured above) would take up to 11 years.
After the whale flesh is eaten, the whale bones which are 60 per cent fat become covered in fat-eating worms, snails, clams and limpets, some of which are only found on whale carcases. First described in 2004 are the bone-eating Zombie worms. They consist of roots that bore into the bones and extract fat with the help of symbiotic bacteria living within the worms.
This second stage of eating, which lasted four years in the 35 tonne grey, is followed by anaerobic bacteria gradually invading the interior of the bones and breaking down the remaining fat while leaching out sulphides. The sulphides sustain a community of clams, limpets, crustaceans, mussels and worms. As many as 185 species can be around the whale skeleton at this stage.
The whale skeleton discovered in 1987 is still being eaten after 60 years and Smith estimates that a large whale could keep going for a 100 years or more. He's hoping for a beached whale in New Zealand as he wants to sink a carcase in those waters to find out how many new species live off whale falls in this area.
In 1934, zoologist August Krogh speculated that dead whales sink to the bottom and are eaten by whatever lives down there but it's taken us this long to find out. It costs Craig Smith around $8,000 to sink each whale but we can't put a price on the data he collects about the abyss dwellers.