Whale fall
Encyclopedia
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.
When a whale dies in shallow water, its carcass is typically devoured by scavengers over a relatively short period of time—within several months. However, in deeper water (depths of 2000 m (6,561.7 ft) or greater), fewer scavenger species exist, and the carcass can provide sustenance for a complex localized ecosystem
over periods of decades. Some of the organisms that have been observed at whale falls are giant isopod
s, squat lobster
s, bristleworms
, prawns, shrimp
, lobsters, hagfish
, Osedax
(bone-eating worms), crabs, sea cucumbers, octopus
es, clams
, and even deep-sea sleeper sharks. Whale falls are often inhabited by large colonies of tubeworms
. Over 30 previously unknown species
have been discovered at whale falls.
oceanographer
Craig Smith in 1987, discovered accidentally by the submersible
Alvin
using scanning sonar at 1240 m (4,068.2 ft) in Santa Catalina, California Basin. Whale falls have since been found by other scientists, and by military submarines. They can be found by using side-scan sonar
to examine the ocean floor for large aggregations of matter.
The first sign that whale carcasses could host specialized animal communities came in 1854 when a new mussel
species was extracted from a piece of floating whale blubber. Beginning in the 1960s, deep sea trawlers unintentionally recovered other new mollusc species including limpet
s (named Osteopelta
) attached to whale bones.
s from Alvin's discovery belonged to groups that harbor chemosynthetic bacteria
which can draw energy from inorganic chemicals. Their only known habitats were sunken wood and hydrothermal vents. The lucinid clams
' only other habitats were seeps and anoxic
seafloor sediments. Similarly, a snail inhabited only anoxic sediments.
Similar ecosystems exist when other large volumes of nutrient-rich material fall to the sea floor. Sunken beds of kelp
create kelp falls, and large tree
s can sink to create wood falls. In more recent years, shipwrecks have also provided bases for deepwater communities.
The initial, mobile scavenger stage features hagfish
and sleeper sharks that consume the soft tissue at a rate of 40–60 kg (88.2–132.3 lb) per day, over a period of up to two years.
The second stage, 'enrichment opportunist', also lasts up to two years. A few species of animals colonize the bones and surrounding sediments. They consume the tissue left by the scavengers.
In the final 'sulfophilic' stage, bacteria anaerobically break down the lipids embedded in the bones. Instead of oxygen
, they reduce dissolved sulfate and excrete hydrogen sulfide
, which is toxic to animals other than certain chemosynthetic bacteria. The mussels and clams are nourished by chemosymbiotic bacteria while the limpets and snails graze on bacterial mats. Whale bones are rich in lipid
s, which represent 4-6% of the whale's body weight. This stage can last 50 to possibly 100 years.
Latin
for bone-devourer) Osedax inhabits whale falls in southern California
, Monterey Bay
, Sweden
, and Japan
. Osedax appendages exchange gas with the water column, but retract if disturbed. Adult Osedax have no digestive tract. Instead they tunnel their green, fleshy 'roots' into the bones to feed their symbiotic bacteria.
to disperse/migrate from one to another.
and Oligocene
(34-23 MYA) in Washington and from the Pliocene
in Italy
include clams that also inhabited non-chemosynthetic environments. Chemosynthetic-only animals do not appear until the Miocene
(23 to 5 MYA) in California and Japan. This may be because the lipid content of early whale bones was too low.
The discovery of the limpet Osteopelta in an Eocene New Zealand turtle bone indicates that these animals predate whales, including possibly inhabiting Mesozoic
(251-65 MYA) reptiles. They may have survived in seeps, wood-falls and vents while waiting out the 20 million year gap between the reptiles' extinction and whales' emergence. Another possibility is that these fossils represent a prior, dead-end evolutionary path, and that today's animals evolved independently.
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...
carcass that has fallen to the ocean
Ocean
An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...
floor. Whale falls were first observed in the 1980s, with the advent of deep-sea robotic exploration.
When a whale dies in shallow water, its carcass is typically devoured by scavengers over a relatively short period of time—within several months. However, in deeper water (depths of 2000 m (6,561.7 ft) or greater), fewer scavenger species exist, and the carcass can provide sustenance for a complex localized ecosystem
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....
over periods of decades. Some of the organisms that have been observed at whale falls are giant isopod
Giant isopod
A giant isopod is any of approximately nine species of large isopods in the genus Bathynomus. They are thought to be abundant in cold, deep waters of the Atlantic...
s, squat lobster
Squat lobster
Squat lobsters are decapod crustaceans of the families Galatheidae, Chirostylidae and Kiwaidae, including the common genera Galathea and Munida. They are not lobsters at all, but are more closely related to porcelain crabs, hermit crabs and then, more distantly, true crabs...
s, bristleworms
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...
, prawns, shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
, lobsters, hagfish
Hagfish
Hagfish, the clade Myxini , are eel-shaped slime-producing marine animals . They are the only living animals that have a skull but not a vertebral column. Along with lampreys, hagfish are jawless and are living fossils whose next nearest relatives include all vertebrates...
, Osedax
Osedax
Osedax is a genus of deep-sea siboglinid polychaetes, commonly called boneworms, zombie worms, or bone-eating worms, or bone-eating snot flowers...
(bone-eating worms), crabs, sea cucumbers, octopus
Octopus
The octopus is a cephalopod mollusc of the order Octopoda. Octopuses have two eyes and four pairs of arms, and like other cephalopods they are bilaterally symmetric. An octopus has a hard beak, with its mouth at the center point of the arms...
es, clams
CLaMS
CLaMS is a modular chemistry transport model system developed at Forschungszentrum Jülich, Germany. CLaMS was first described by McKenna et al. and was expanded into three dimensions by Konopka et al....
, and even deep-sea sleeper sharks. Whale falls are often inhabited by large colonies of tubeworms
Tube worm
A tube worm is a worm-like sessile invertebrate that anchors its tail to an underwater surface and secretes around its body a mineral tube, into which it can withdraw its entire body.Tube worms are found among the following taxa:...
. Over 30 previously unknown species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
have been discovered at whale falls.
Discovery
A whale fall was first observed by marine biologists led by University of HawaiiUniversity of Hawaii
The University of Hawaii System, formally the University of Hawaii and popularly known as UH, is a public, co-educational college and university system that confers associate, bachelor, master, and doctoral degrees through three university campuses, seven community college campuses, an employment...
oceanographer
Oceanography
Oceanography , also called oceanology or marine science, is the branch of Earth science that studies the ocean...
Craig Smith in 1987, discovered accidentally by the submersible
Submersible
A submersible is a small vehicle designed to operate underwater. The term submersible is often used to differentiate from other underwater vehicles known as submarines, in that a submarine is a fully autonomous craft, capable of renewing its own power and breathing air, whereas a submersible is...
Alvin
DSV Alvin
Alvin is a manned deep-ocean research submersible owned by the United States Navy and operated by the Woods Hole Oceanographic Institution in Woods Hole, Massachusetts. The vehicle was built by General Mills' Electronics Group in the same factory used to manufacture breakfast cereal-producing...
using scanning sonar at 1240 m (4,068.2 ft) in Santa Catalina, California Basin. Whale falls have since been found by other scientists, and by military submarines. They can be found by using side-scan sonar
Side-scan sonar
Side-scan sonar is a category of sonar system that is used to efficiently create an image of large areas of the sea floor...
to examine the ocean floor for large aggregations of matter.
The first sign that whale carcasses could host specialized animal communities came in 1854 when a new mussel
Mussel
The common name mussel is used for members of several families of clams or bivalvia mollusca, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, which are often more or less rounded or oval.The...
species was extracted from a piece of floating whale blubber. Beginning in the 1960s, deep sea trawlers unintentionally recovered other new mollusc species including limpet
Limpet
Limpet is a common name for a number of different kinds of saltwater and freshwater snails ; it is applied to those snails that have a simple shell which is more or less conical in shape, and either is not spirally coiled, or appears not to be coiled in the adult snails.The name limpet is most...
s (named Osteopelta
Osteopelta
Osteopelta is a genus of sea snails, marine gastropod mollusks in the family Osteopeltidae.-Species:Species within the genus Osteopelta include:* Osteopelta ceticola Warén, 1989* Osteopelta mirabilis Marshall, 1987...
) attached to whale bones.
Discrete ecosystem
A consistent group of organisms inhabits whale falls in all oceans. The mussels and vesicomyid clamVesicomyidae
Vesicomyidae is a family of bivalves. Its genera, with some selected species, are:* Adulomya Kuroda, 1931 ** Adulomya elongata...
s from Alvin's discovery belonged to groups that harbor chemosynthetic bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
which can draw energy from inorganic chemicals. Their only known habitats were sunken wood and hydrothermal vents. The lucinid clams
Lucinidae
Lucinidae is a family of saltwater clams, marine bivalve molluscs.These bivalves are remarkable for their endosymbiosis with sulphide-oxidizing bacteria.-Characteristics:...
' only other habitats were seeps and anoxic
Hypoxia (environmental)
Hypoxia, or oxygen depletion, is a phenomenon that occurs in aquatic environments as dissolved oxygen becomes reduced in concentration to a point where it becomes detrimental to aquatic organisms living in the system...
seafloor sediments. Similarly, a snail inhabited only anoxic sediments.
Similar ecosystems exist when other large volumes of nutrient-rich material fall to the sea floor. Sunken beds of kelp
Kelp
Kelps are large seaweeds belonging to the brown algae in the order Laminariales. There are about 30 different genera....
create kelp falls, and large tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
s can sink to create wood falls. In more recent years, shipwrecks have also provided bases for deepwater communities.
Three stages
The Santa Catalina falls but not others, consistently exhibit three stages of decomposition.The initial, mobile scavenger stage features hagfish
Hagfish
Hagfish, the clade Myxini , are eel-shaped slime-producing marine animals . They are the only living animals that have a skull but not a vertebral column. Along with lampreys, hagfish are jawless and are living fossils whose next nearest relatives include all vertebrates...
and sleeper sharks that consume the soft tissue at a rate of 40–60 kg (88.2–132.3 lb) per day, over a period of up to two years.
The second stage, 'enrichment opportunist', also lasts up to two years. A few species of animals colonize the bones and surrounding sediments. They consume the tissue left by the scavengers.
In the final 'sulfophilic' stage, bacteria anaerobically break down the lipids embedded in the bones. Instead of oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
, they reduce dissolved sulfate and excrete hydrogen sulfide
Hydrogen sulfide
Hydrogen sulfide is the chemical compound with the formula . It is a colorless, very poisonous, flammable gas with the characteristic foul odor of expired eggs perceptible at concentrations as low as 0.00047 parts per million...
, which is toxic to animals other than certain chemosynthetic bacteria. The mussels and clams are nourished by chemosymbiotic bacteria while the limpets and snails graze on bacterial mats. Whale bones are rich in 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, which represent 4-6% of the whale's body weight. This stage can last 50 to possibly 100 years.
Osedax
The differences regarding the Santa Catalina falls may have to do with insufficient oxygen at the site. Another contributing factor may be the presence of 1-cm (0.4 in) zombie worm (OsedaxOsedax
Osedax is a genus of deep-sea siboglinid polychaetes, commonly called boneworms, zombie worms, or bone-eating worms, or bone-eating snot flowers...
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-devourer) Osedax inhabits whale falls in southern 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...
, 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....
, 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....
, and Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. Osedax appendages exchange gas with the water column, but retract if disturbed. Adult Osedax have no digestive tract. Instead they tunnel their green, fleshy 'roots' into the bones to feed their symbiotic bacteria.
Stepping stones
Smith and his colleagues suggested in 1989 that such species may use whale falls as stepping-stones to extend their range across multiple chemosynthetic communities. They estimate that 690,000 carcasses/skeletons of the 9 largest whale species are in one of the three stages at any one time. This estimate implies an average spacing of 12 kilometres (7.5 mi) and as little as 5 kilometres (3.1 mi) along migration routes. They hypothesize that this distance is short enough to allow larvaeLarvae
In Roman mythology, lemures were shades or spirits of the restless or malignant dead, and are probably cognate with an extended sense of larvae as disturbing or frightening...
to disperse/migrate from one to another.
The fossil record
Whale fall fossils from the late EoceneEocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
and Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
(34-23 MYA) in Washington and from the Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
in Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
include clams that also inhabited non-chemosynthetic environments. Chemosynthetic-only animals do not appear until the Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
(23 to 5 MYA) in California and Japan. This may be because the lipid content of early whale bones was too low.
The discovery of the limpet Osteopelta in an Eocene New Zealand turtle bone indicates that these animals predate whales, including possibly inhabiting Mesozoic
Mesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
(251-65 MYA) reptiles. They may have survived in seeps, wood-falls and vents while waiting out the 20 million year gap between the reptiles' extinction and whales' emergence. Another possibility is that these fossils represent a prior, dead-end evolutionary path, and that today's animals evolved independently.