Australian Giant Cuttlefish
Encyclopedia
Sepia apama, also known as the Australian Giant Cuttlefish, is the world's largest cuttlefish
species, growing to 50 cm in mantle
length and over 10.5 kg
(23 lb
) in weight. Using cells known as chromatophore
s, the cuttlefish can put on spectacular displays, changing colour in an instant.
S. apama is native to the southern coast of Australia
, from Brisbane
in Queensland
to Shark Bay
in Western Australia
. It occurs on rocky reefs, seagrass
beds, and sand and mud seafloor to a depth of 100 m.
population is the world's only known mass cuttlefish spawning aggregation and the Sepia apama congregate around Point Lowly near Whyalla between May and August. With densities of one cuttlefish per square metre, the sheer number of Sepia apama makes this breeding aggregation unique in the world. As the cuttlefish are oblivious to divers while spawning, they are now a major attraction for divers from around the world.
The Sepia apama upper Spencer Gulf population displays two alternative life cycles in both sexes (growth pattern polymorphism
). The first involves rapid growth with maturity reached in seven to eight months with small adults returning to spawn in the first year. The second involves slow growth with maturity reached in two years with large adults returning to spawn in the second year.
Prior to the mid-1990s, the population was fished for snapper
bait. Between 1995 and 1997 commercial fishing of the spawning grounds harvested around 450 tonnes leading to 50% of the grounds being closed to commercial fishing in 1998. In 2005 the closure was expanded to the entire spawning grounds.
In 2011 the cuttlefish failed to return to breed. Beginning in May, the cuttlefish leave deep water and migrate along coastal reefs to reach their spawning grounds. Local fishermen claim that a small "finger of land" near Point Lowly extends outside the exclusion zone and that commercial fishers have been targeting the area, intercepting the Sepia apama before they can reach the spawning grounds. Being semelparous breeders, ecologist Bronwyn Gillanders believes the cuttlefish to be in danger, stating that it is hard to determine whether this a natural phenomenon or something else and that the cause requires more research.
. The plant appears to have had no effect on cuttlefish spawning despite being located in the middle of the grounds. Santos now provides funding for cuttlefish research.
BHP Billiton
has plans to build a desalination
plant at Point Lowly to supply fresh water to Roxby Downs. The plant, located within 200 metres (656.2 ft) of the breeding grounds, will dump around 120 millilitre of brine
(46–60 ppt) into the area each day. As cuttlefish embryos die off as salinity levels rise (optimal range 28–38 ppt, 100% mortality at 50 ppt), there has been considerable public opposition to the proposed plant because of the expected environmental impact.
Due to its proximity to the ore deposits of the Middleback Ranges, several mining companies have indicated they want to build petrochemical and diesel refining facilities at Point Lowly. A second jetty for the loading of iron ore, and possibly copper and uranium
, is also planned. The Cuttlefish Coast Coalition has been formed to fight these proposed developments.
As a result of the above threats to the population, in 2010 an application was made to list Sepia apama in the list of threatened species. On February 2, 2011, the Threatened Species Scientific Committee ruled the species was not eligible for listing as the affected population was not taxonomically distinct from the rest of Sepia apama for the purposes of the Act.
Genetic studies have shown that there is little if any interbreeding between Sepia apama populations. While there is some genetic divergence, the various populations are not considered taxonomically distinct and are commonly referred to by their location, e.g. Sepia apama upper Spencer Gulf population.
Sepia apama is a neritic
demersal species. Using neurally controlled
cells known as chromatophore
organs (red to yellow), iridophores (iridescent: spans the entire visible spectrum from blue to near-IR
) and leucophores (white), the cuttlefish can put on spectacular displays, changing colour and patterns in a fraction of a second. Located in three layers under the skin, leucophores make up the bottom layer, with chromatophores the outermost. By selective blocking, the three layers work together to produce polarised patterns. Unlike those in most animals, cuttlefish iridophores are physiologically active; they can change their reflectivity and the degree of polarization can also be controlled. Cuttlefish are colourblind
, however the photoreceptors of cuttlefish eyes are arranged in a way which gives them the ability to see the linear polarization of light. While the Mantis shrimp
is the only known creature to have true polarization vision, it is believed that cephalopod
s may also. Because the optic lobes of cuttlefish are larger than any other region of the brain and their skin produces polarized reflective patterns, it has been postulated that they may communicate through this visual system. By raising elaborate papillae
on their skin, S. apama can change the shape and the texture of their skin to imitate rock, sand or seaweed.
A recent energetics study found that Sepia apama are primarily diurnal and have a small home range (90–550 meters) over short recording periods while travelling large distances to breed. They are able to channel most of their energy directly into growth because they spend 95% of the day resting, suggesting bioenergetics more like that of an octopus
than a squid
. Very little time is spent foraging (3.7% during the day and 2.1% during the night), most of their time is spent resting and hiding in crevices from predators. The exception to this behavioral routine is the mass spawning aggregation, where cuttlefish are far more active during the days or weeks that they spend there.
s, which have been observed (in South Australia's Spencer Gulf
) to have developed a technique for removing the ink and cuttlebone
from a cuttlefish before eating it.
Cuttlefish
Cuttlefish are marine animals of the order Sepiida. They belong to the class Cephalopoda . Despite their name, cuttlefish are not fish but molluscs....
species, growing to 50 cm in mantle
Mantle (mollusc)
The mantle is a significant part of the anatomy of molluscs: it is the dorsal body wall which covers the visceral mass and usually protrudes in the form of flaps well beyond the visceral mass itself.In many, but by no means all, species of molluscs, the epidermis of the mantle secretes...
length and over 10.5 kg
Kilogram
The kilogram or kilogramme , also known as the kilo, is the base unit of mass in the International System of Units and is defined as being equal to the mass of the International Prototype Kilogram , which is almost exactly equal to the mass of one liter of water...
(23 lb
Pound (mass)
The pound or pound-mass is a unit of mass used in the Imperial, United States customary and other systems of measurement...
) in weight. Using cells known as chromatophore
Chromatophore
Chromatophores are pigment-containing and light-reflecting cells found in amphibians, fish, reptiles, crustaceans, and cephalopods. They are largely responsible for generating skin and eye colour in cold-blooded animals and are generated in the neural crest during embryonic development...
s, the cuttlefish can put on spectacular displays, changing colour in an instant.
S. apama is native to the southern coast of Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, from Brisbane
Brisbane
Brisbane is the capital and most populous city in the Australian state of Queensland and the third most populous city in Australia. Brisbane's metropolitan area has a population of over 2 million, and the South East Queensland urban conurbation, centred around Brisbane, encompasses a population of...
in Queensland
Queensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
to Shark Bay
Shark Bay
Shark Bay is a World Heritage listed bay in Western Australia. The term may also refer to:* the locality of Shark Bay, now known as Denham* Shark Bay Marine Park* Shark Bay , a shark exhibit at Sea World, Gold Coast, Australia* Shire of Shark Bay...
in Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
. It occurs on rocky reefs, seagrass
Seagrass
Seagrasses are flowering plants from one of four plant families , all in the order Alismatales , which grow in marine, fully saline environments.-Ecology:...
beds, and sand and mud seafloor to a depth of 100 m.
Life cycle and reproduction
Sepia apama live from two to three years. Breeding takes place with the onset of the southern winter. Males, which outnumber females 11 to 1, abandon their normal cryptic colouring and set out to dazzle the females by adopting rapidly changing bright colours and striking patterns. Devious males mimic female colouring and form in order to gain access to females protected by dominant males which are extremely territorial. Females are polyandrous, and collaborative research indicates the tendency for females to reproduce using male genetic material deposited in spermatangia more favorably than in sperm receptacles directly. Females then attach their eggs to the underside of rocks where they will hatch within three to five months. Sepia apama are semelparous and death follows shortly after a single mating and laying of eggs that will spawn the next generation.Upper Spencer Gulf population
Discovered by divers in the late 1990s, the upper Spencer GulfSpencer Gulf
The Spencer Gulf is the westernmost of two large inlets on the southern coast of Australia, in the state of South Australia, facing the Great Australian Bight. The Gulf is 322 km long and 129 km wide at its mouth. The western shore of the Gulf is the Eyre Peninsula, while the eastern side is the...
population is the world's only known mass cuttlefish spawning aggregation and the Sepia apama congregate around Point Lowly near Whyalla between May and August. With densities of one cuttlefish per square metre, the sheer number of Sepia apama makes this breeding aggregation unique in the world. As the cuttlefish are oblivious to divers while spawning, they are now a major attraction for divers from around the world.
The Sepia apama upper Spencer Gulf population displays two alternative life cycles in both sexes (growth pattern polymorphism
Polymorphism (biology)
Polymorphism in biology occurs when two or more clearly different phenotypes exist in the same population of a species — in other words, the occurrence of more than one form or morph...
). The first involves rapid growth with maturity reached in seven to eight months with small adults returning to spawn in the first year. The second involves slow growth with maturity reached in two years with large adults returning to spawn in the second year.
Prior to the mid-1990s, the population was fished for snapper
Lutjanidae
Snappers are a family of perciform fish, mainly marine but with some members inhabiting estuaries, feeding in freshwater. Some are important food fish. One of the best known is the red snapper....
bait. Between 1995 and 1997 commercial fishing of the spawning grounds harvested around 450 tonnes leading to 50% of the grounds being closed to commercial fishing in 1998. In 2005 the closure was expanded to the entire spawning grounds.
In 2011 the cuttlefish failed to return to breed. Beginning in May, the cuttlefish leave deep water and migrate along coastal reefs to reach their spawning grounds. Local fishermen claim that a small "finger of land" near Point Lowly extends outside the exclusion zone and that commercial fishers have been targeting the area, intercepting the Sepia apama before they can reach the spawning grounds. Being semelparous breeders, ecologist Bronwyn Gillanders believes the cuttlefish to be in danger, stating that it is hard to determine whether this a natural phenomenon or something else and that the cause requires more research.
Effect of local industrialisation
In 1984, before the spawning grounds were discovered, Santos built a hydrocarbon processing plant at Port BonythonPort Bonython
Port Bonython is a deepwater port at the head of Spencer Gulf, 20 km eastnortheast of Whyalla. It is capable of taking Capesize ships. It was established in 1982 and named after John Bonython, the founding chairman of Santos Ltd.-Overview:...
. The plant appears to have had no effect on cuttlefish spawning despite being located in the middle of the grounds. Santos now provides funding for cuttlefish research.
BHP Billiton
BHP Billiton
BHP Billiton is a global mining, oil and gas company headquartered in Melbourne, Australia and with a major management office in London, United Kingdom...
has plans to build a desalination
Desalination
Desalination, desalinization, or desalinisation refers to any of several processes that remove some amount of salt and other minerals from saline water...
plant at Point Lowly to supply fresh water to Roxby Downs. The plant, located within 200 metres (656.2 ft) of the breeding grounds, will dump around 120 millilitre of brine
Brine
Brine is water, saturated or nearly saturated with salt .Brine is used to preserve vegetables, fruit, fish, and meat, in a process known as brining . Brine is also commonly used to age Halloumi and Feta cheeses, or for pickling foodstuffs, as a means of preserving them...
(46–60 ppt) into the area each day. As cuttlefish embryos die off as salinity levels rise (optimal range 28–38 ppt, 100% mortality at 50 ppt), there has been considerable public opposition to the proposed plant because of the expected environmental impact.
Due to its proximity to the ore deposits of the Middleback Ranges, several mining companies have indicated they want to build petrochemical and diesel refining facilities at Point Lowly. A second jetty for the loading of iron ore, and possibly copper and uranium
Yellowcake
Yellowcake is a kind of uranium concentrate powder obtained from leach solutions, in an intermediate step in the processing of uranium ores. Yellowcake concentrates are prepared by various extraction and refining methods, depending on the types of ores...
, is also planned. The Cuttlefish Coast Coalition has been formed to fight these proposed developments.
As a result of the above threats to the population, in 2010 an application was made to list Sepia apama in the list of threatened species. On February 2, 2011, the Threatened Species Scientific Committee ruled the species was not eligible for listing as the affected population was not taxonomically distinct from the rest of Sepia apama for the purposes of the Act.
Physiology and biochemistry
Sepia apama is a neritic
Neritic zone
The neritic zone, also called coastal waters, the coastal ocean or the sublittoral zone, is the part of the ocean extending from the low tide mark to the edge of the continental shelf, with a relatively shallow depth extending to about 200 meters...
demersal species. Using neurally controlled
Nervous system
The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body. In most animals the nervous system consists of two parts, central and peripheral. The central nervous...
cells known as chromatophore
Chromatophore
Chromatophores are pigment-containing and light-reflecting cells found in amphibians, fish, reptiles, crustaceans, and cephalopods. They are largely responsible for generating skin and eye colour in cold-blooded animals and are generated in the neural crest during embryonic development...
organs (red to yellow), iridophores (iridescent: spans the entire visible spectrum from blue to near-IR
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
) and leucophores (white), the cuttlefish can put on spectacular displays, changing colour and patterns in a fraction of a second. Located in three layers under the skin, leucophores make up the bottom layer, with chromatophores the outermost. By selective blocking, the three layers work together to produce polarised patterns. Unlike those in most animals, cuttlefish iridophores are physiologically active; they can change their reflectivity and the degree of polarization can also be controlled. Cuttlefish are colourblind
Color blindness
Color blindness or color vision deficiency is the inability or decreased ability to see color, or perceive color differences, under lighting conditions when color vision is not normally impaired...
, however the photoreceptors of cuttlefish eyes are arranged in a way which gives them the ability to see the linear polarization of light. While the Mantis shrimp
Mantis shrimp
Mantis shrimp or stomatopods are marine crustaceans, the members of the order Stomatopoda. They are neither shrimp nor mantids, but receive their name purely from the physical resemblance to both the terrestrial praying mantis and the shrimp. They may reach in length, although exceptional cases of...
is the only known creature to have true polarization vision, it is believed that cephalopod
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda . These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot...
s may also. Because the optic lobes of cuttlefish are larger than any other region of the brain and their skin produces polarized reflective patterns, it has been postulated that they may communicate through this visual system. By raising elaborate papillae
Papule
A papule is a circumscribed, solid elevation of skin with no visible fluid, varying in size from a pinhead to 1 cm.With regard to the quote "...varying in size from a pinhead to 1cm," depending on which text is referenced, some authors state the cutoff between a papule and a plaque as 0.5cm,...
on their skin, S. apama can change the shape and the texture of their skin to imitate rock, sand or seaweed.
A recent energetics study found that Sepia apama are primarily diurnal and have a small home range (90–550 meters) over short recording periods while travelling large distances to breed. They are able to channel most of their energy directly into growth because they spend 95% of the day resting, suggesting bioenergetics more like that of an 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...
than a squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...
. Very little time is spent foraging (3.7% during the day and 2.1% during the night), most of their time is spent resting and hiding in crevices from predators. The exception to this behavioral routine is the mass spawning aggregation, where cuttlefish are far more active during the days or weeks that they spend there.
Role in ecosystem
The Australian Giant Cuttlefish is eaten by Indo-Pacific bottlenose dolphinIndo-Pacific Bottlenose Dolphin
The Indo-Pacific bottlenose dolphin is a species of bottlenose dolphin. The Indo-Pacific bottlenose dolphin grows to long, and weigh up to . It lives in the waters around India, northern Australia, South China, the Red Sea, and the eastern coast of Africa. Its back is dark grey and its belly...
s, which have been observed (in South Australia's Spencer Gulf
Spencer Gulf
The Spencer Gulf is the westernmost of two large inlets on the southern coast of Australia, in the state of South Australia, facing the Great Australian Bight. The Gulf is 322 km long and 129 km wide at its mouth. The western shore of the Gulf is the Eyre Peninsula, while the eastern side is the...
) to have developed a technique for removing the ink and cuttlebone
Cuttlebone
Cuttlebone, also known as cuttlefish bone, is a hard, brittle internal structure found in all members of the family Sepiidae, commonly known as cuttlefish....
from a cuttlefish before eating it.
External links
- Video of Sepia apama at YouTubeYouTubeYouTube is a video-sharing website, created by three former PayPal employees in February 2005, on which users can upload, view and share videos....