Last week I was writing an essay about belief in cryptozoology, the pseudoscience (or speculative science, depending on whom you ask) dealing with hidden or suspected animals called cryptids. One such cryptid is the “globster,” an unidentifiable organic mass that washes up on beaches. Believers have long held the globster as evidence of sea monsters. Scientists insist these blobs are the remains of large marine life like whales, sharks, or squid. In the process of researching this topic, it got me wondering. After whales expire, do their bodies float or sink? Is the vast ocean filled with floating whale carcasses? Google’s search suggestions tell me I am not the only one wondering. As it turns out, they float for a little while and then sink to the ocean floor in what is called a “whale fall.” When a whale carcass sinks to the bottom of the ocean, it provides a habitat for other deep-sea life for 60–100 years. There are some organisms that are found nowhere else in the world other than on whale falls. The first natural whale fall discovered and studied was that of a 20-meter-long blue or fin whale found in the Santa Catalina Basin on November 10, 1987 by oceanographer Dr. Craig R. Smith and his team (SOEST, University of Hawai‘i at Mānoa). Smith describes the three main stages of whale fall progression. When the whale reaches the bottom of the ocean, scavengers can smell the remains, and within minutes, will be feasting on the whale’s soft tissue. This is the beginning of the “mobile scavenger stage.” Hundreds of hagfish burrow into the carcass, and stone crabs, sharks, shrimp, and other invertebrates feed as well. Depending on the size of the whale, this can take a few months to a few years. Next comes the “enrichment opportunist stage,” which can also take months to years. During this period, when bones are exposed and tissue has enriched the sea floor, other crustaceans and worms – millions of worms – move in. The whale fall during this stage looks like it sits on a lawn of white grass, according to Smith. Finally the “sulfophilic (sulfur-loving) stage” begins and can last for decades. During this stage, anaerobic bacteria feed off the lipids in whale bones and release sulfide, which nourishes more bacteria, which in turn feeds mussels, isopods, and more worms. You can listen to Dr. Smith talk about whale falls in the Oct. 4, 2011 episode of Radiolab called Loops. The segment, which starts at 00:27:40, also inspired this gorgeous short film. [vimeo 29987934] Smith and his colleagues have studied naturally occurring whale falls, but much of their research comes from artificially sunk carcasses. Sometimes when a beached whale cannot be saved, researchers will tow it back out to sea and sink it to study the process by which the remains become part of the ecosystem. Finding natural whale falls is exceedingly rare. Until recently, only five had ever been found. But marine biologists just announced the first discovery of a natural whale fall in the Southern Ocean. The skeleton, estimated to be several decades old, was found in the South Sandwich Arc and determined to be from an Antarctic minke whale. The research team responsible for the discovery includes members from the Natural History Museum of London, National Oceanography Centre, University of Southampton, British Antarctic Survey, and Oxford University. “At the moment, the only way to find a whale fall is to navigate right over one with an underwater vehicle,” explains Dr. Jon Copley in a statement released by Southampton. “We were just finishing a dive with the UK's remotely operated vehicle, Isis, when we glimpsed a row of pale-coloured blocks in the distance, which turned out to be whale vertebrae on the seabed,” he continues. The team found nine species previously undescribed (or hidden, as a cryptozoologist might assert). Among them were sea snails, crustaceans, and worms, like the “bone-eating zombie worm.” Study of this find also provided further insight into the ecological role of whale falls. “One of the great remaining mysteries of deep ocean biology is how these tiny invertebrates can spread between the isolated habitats these whale carcasses provide on the seafloor,” says team member Dr. Adrian Glover (Natural History Museum). “Our discovery fills important gaps in this knowledge.” Their research is published online in the journal Deep Sea Research Part II: Topical Studies in Oceanography.
Apr 8, 2013