Osedax
Encyclopedia
Osedax is a genus
of deep-sea siboglinid polychaete
s, commonly called boneworms, zombie worms, or bone-eating worms, or bone-eating snot flowers. Osedax is Latin
for "bone-eating", the name alluding to how the worms bore into the bones of whale
carcasses to reach enclosed lipid
s, on which they rely for sustenance.
Scientists from the Monterey Bay Aquarium Research Institute
using the submarine ROV Tiburon first discovered the genus in Monterey Bay
, California
, in February 2002. The worms were found living on the bones of a decaying gray whale
in the Monterey Canyon
, at a depth of 2893 m (9,491.5 ft)
species of bacteria to digest whale fat and oils and release nutrients that they can absorb. Osedax have colorful feathery plumes that act as gill
s, and unusual root-like structures that absorb nutrients. Between 50 and 100 microscopic dwarf males live inside a single female, and never develop past the larval stage.
ing both in the wild and in laboratory aquaria (Rouse et al. 2009). Osedax rubiplumus can spawn hundreds of oocyte
s at a time. The worms' endosymbiont
, the bacteria Oceanospirillales
, was not observed in the spawned oocytes, which suggests they are acquired after the worms settle on bones. In the adult, the bacteria are localised in the root-like structures that grow into the whale bone. This worm appears to be highly fecund and reproduces continuously. This may help explain why Osedax is such a diverse genus, despite the rarity of whale fall
s in the ocean.
Male Osedax are microscopic dwarfs that live as "harems" inside the lumen of the gelatinous tube that surrounds each female. An individual female can house hundreds of these males in her tube.
in 2004.
In late 2005, an experiment by Swedish marine biologists resulted in the discovery of a species of the worm in the North Sea
off the west coast of Sweden
. In the experiment, a minke whale
carcass that had been washed ashore had been sunk to a depth of 120 m (393.7 ft) and monitored for several months. Biologists were surprised to find that unlike the previous discoveries, the new species, colloquially known as "bone eating snot flower" after its scientific name (Osedax mucofloris; a more accurate translation would be "slimeflower bone-eater"), lived in very shallow waters compared to the previous discoveries.
In November 2009, researchers reported finding as many as 15 species of boneworms living in Monterey Bay on the California coast.
paradox: despite the rarity and ephemeral nature of whale fall
s, Osedax has a broad biogeographic range and is surprisingly diverse. One hypothesis advanced to explain this paradox is that Osedax are able to colonize a variety of vertebrate remains besides whalebones. This hypothesis is supported by an experiment involving cow bones suspended above the sea floor. A variety of Osedax species successfully colonized these bones. Osedax have also been observed colonizing terrestrial mammal bones mixed in with galley waste from a surface vessel. Other scientists have countered this hypothesis by pointing out how the cow bone experiment does not match any natural habitat and also the low probability of terrestrial mammal bones arriving at the ocean floor in significant quantities. They also point out other cases of food falls in which the remains disappeared too swiftly for Osedax colonization and the lack of any observed colonization in similar cases. The true role of Osedax in the degradation of marine vertebrate remains is important to marine vertebrate taphonomy
. Burrows closely similar to those made by Osedax species have been found in the bones of ancient marine birds
, suggesting that the genus may once have had a wider range of foods.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of deep-sea siboglinid polychaete
Polychaete
The Polychaeta or polychaetes are a class of annelid worms, generally marine. Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made of chitin. Indeed, polychaetes are sometimes referred to as bristle worms. More than 10,000...
s, commonly called boneworms, zombie worms, or bone-eating worms, or bone-eating snot flowers. Osedax is Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
for "bone-eating", the name alluding to how the worms bore into the bones of whale
Whale
Whale is the common name for various marine mammals of the order Cetacea. The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which belong to suborder Odontoceti . This suborder also includes the sperm whale, killer whale, pilot whale, and beluga...
carcasses to reach enclosed lipid
Lipid
Lipids constitute a broad group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, triglycerides, phospholipids, and others...
s, on which they rely for sustenance.
Scientists from the Monterey Bay Aquarium Research Institute
Monterey Bay Aquarium Research Institute
The Monterey Bay Aquarium Research Institute is a not-for-profit oceanographic research center in Moss Landing, California affiliated with the Monterey Bay Aquarium. It was founded in 1987 by David Packard of Hewlett-Packard fame...
using the submarine ROV Tiburon first discovered the genus in Monterey Bay
Monterey Bay
Monterey Bay is a bay of the Pacific Ocean, along the central coast of California. The bay is south of San Francisco and San Jose, between the cities of Santa Cruz and Monterey....
, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, in February 2002. The worms were found living on the bones of a decaying gray whale
Gray Whale
The gray whale, Eschrichtius robustus, is a baleen whale that migrates between feeding and breeding grounds yearly. It reaches a length of about , a weight of , and lives 50–70 years. The common name of the whale comes from the gray patches and white mottling on its dark skin. Gray whales were...
in the Monterey Canyon
Monterey Canyon
Monterey Canyon, or Monterey Submarine Canyon, is a submarine canyon in Monterey Bay, California. It is the subject of ongoing study by the scientists at the Monterey Bay Aquarium Research Institute, the Moss Landing Marine Laboratories, and other oceanographic institutions.Monterey Canyon begins...
, at a depth of 2893 m (9,491.5 ft)
Anatomy and physiology
Lacking stomach and mouth, Osedax rely on symbioticSymbiosis
Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...
species of bacteria to digest whale fat and oils and release nutrients that they can absorb. Osedax have colorful feathery plumes that act as gill
Gill
A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...
s, and unusual root-like structures that absorb nutrients. Between 50 and 100 microscopic dwarf males live inside a single female, and never develop past the larval stage.
Reproduction
Female Osedax worms have been observed spawnSpawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...
ing both in the wild and in laboratory aquaria (Rouse et al. 2009). Osedax rubiplumus can spawn hundreds of oocyte
Oocyte
An oocyte, ovocyte, or rarely ocyte, is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. An oocyte is produced in the ovary during female gametogenesis. The female germ cells produce a primordial germ cell which undergoes a mitotic...
s at a time. The worms' endosymbiont
Endosymbiont
An endosymbiont is any organism that lives within the body or cells of another organism, i.e. forming an endosymbiosis...
, the bacteria Oceanospirillales
Oceanospirillales
The Oceanospirillales are an order of Proteobacteria, with two families .One strain of Oceanospirillales is an endosymbiont of the Osedax worms. They are not present in Osedax oocytes so they are acquired later on....
, was not observed in the spawned oocytes, which suggests they are acquired after the worms settle on bones. In the adult, the bacteria are localised in the root-like structures that grow into the whale bone. This worm appears to be highly fecund and reproduces continuously. This may help explain why Osedax is such a diverse genus, despite the rarity of whale fall
Whale fall
Whale fall is the term used for a whale carcass that has fallen to the ocean floor. Whale falls were first observed in the 1980s, with the advent of deep-sea robotic exploration....
s in the ocean.
Male Osedax are microscopic dwarfs that live as "harems" inside the lumen of the gelatinous tube that surrounds each female. An individual female can house hundreds of these males in her tube.
History
Following its discovery in 2002, the genus was announced in ScienceScience (journal)
Science is the academic journal of the American Association for the Advancement of Science and is one of the world's top scientific journals....
in 2004.
In late 2005, an experiment by Swedish marine biologists resulted in the discovery of a species of the worm in the North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...
off the west coast of Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
. In the experiment, a minke whale
Minke Whale
Minke whale , or lesser rorqual, is a name given to two species of marine mammal belonging to a clade within the suborder of baleen whales. The minke whale was given its official designation by Lacepède in 1804, who described a dwarf form of Balænoptera acuto-rostrata...
carcass that had been washed ashore had been sunk to a depth of 120 m (393.7 ft) and monitored for several months. Biologists were surprised to find that unlike the previous discoveries, the new species, colloquially known as "bone eating snot flower" after its scientific name (Osedax mucofloris; a more accurate translation would be "slimeflower bone-eater"), lived in very shallow waters compared to the previous discoveries.
In November 2009, researchers reported finding as many as 15 species of boneworms living in Monterey Bay on the California coast.
Niche
The role of Osedax in the degradation of marine vertebrate remains is controversial. Some scientists think that Osedax is a specialist on whalebones while others think that it is more of a generalist. This controversy is due to a biogeographicBiogeography
Biogeography is the study of the distribution of species , organisms, and ecosystems in space and through geological time. Organisms and biological communities vary in a highly regular fashion along geographic gradients of latitude, elevation, isolation and habitat area...
paradox: despite the rarity and ephemeral nature of whale fall
Whale fall
Whale fall is the term used for a whale carcass that has fallen to the ocean floor. Whale falls were first observed in the 1980s, with the advent of deep-sea robotic exploration....
s, Osedax has a broad biogeographic range and is surprisingly diverse. One hypothesis advanced to explain this paradox is that Osedax are able to colonize a variety of vertebrate remains besides whalebones. This hypothesis is supported by an experiment involving cow bones suspended above the sea floor. A variety of Osedax species successfully colonized these bones. Osedax have also been observed colonizing terrestrial mammal bones mixed in with galley waste from a surface vessel. Other scientists have countered this hypothesis by pointing out how the cow bone experiment does not match any natural habitat and also the low probability of terrestrial mammal bones arriving at the ocean floor in significant quantities. They also point out other cases of food falls in which the remains disappeared too swiftly for Osedax colonization and the lack of any observed colonization in similar cases. The true role of Osedax in the degradation of marine vertebrate remains is important to marine vertebrate taphonomy
Taphonomy
Taphonomy is the study of decaying organisms over time and how they become fossilized . The term taphonomy was introduced to paleontology in 1940 by Russian scientist Ivan Efremov to describe the study of the transition of remains, parts, or products of organisms, from the biosphere, to the...
. Burrows closely similar to those made by Osedax species have been found in the bones of ancient marine birds
Plotopteridae
Plotopteridae is the name of an extinct family of flightless seabirds from the order Pelecaniformes. Related to the gannets and boobies, they exhibited remarkable convergent evolution with the penguins, particularly with the now extinct giant penguins...
, suggesting that the genus may once have had a wider range of foods.
Species
- Osedax frankpressi
- Osedax japonicus
- Osedax mucoflorisOsedax mucoflorisOsedax mucofloris is a species of bathypelagic Polychaetes that is reported to sustain itself on the bones of dead whales. Translated from the mixed Greek and Latin used in scientific names, "Osedax mucofloris" literally means "bone-eating snot-flower"....
- Osedax roseus
- Osedax rubiplumus
Further reading
- Jones, W.J., Johnson, S.B., Rouse, G.W. & Vrijenhoek, R.C. 2008 Marine worms (genus Osedax) colonize cow bones. Proceedings of the Royal Society B: Biological Sciences 275: 387-391.
External links
- Press release describing discovery of Osedax
- BBC website - link to story about discovery of Osedax worms in the North Sea
- A Motley Collection of Boneworms - Monterey Bay Aquarium Research Institute