Takifugu
Encyclopedia
Takifugu is a genus
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 pufferfish
Pufferfish
Tetraodontidae is a family of primarily marine and estuarine fish of the Tetraodontiformes order. The family includes many familiar species which are variously called pufferfish, balloonfish, blowfish, bubblefish, globefish, swellfish, toadfish, toadies, honey toads, sugar toads, and sea squab...

, often better known by the Japanese name . There are 25 species belonging to the genus Takifugu, which can be found worldwide from about 45° latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...

 north to 45° latitude south, mostly in salt water. Their diet consists mostly of algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...

, molluscs, invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...

s and sometimes crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s. The fish defend themselves by inflating their bodies to several times normal size and by poisoning their predators. These defenses allow the fish to actively explore their environment without much fear of being attacked.

The fish is highly toxic, but despite this — or perhaps because of it — it is considered a delicacy in 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...

. The fish contains lethal amounts of the poison tetrodotoxin
Tetrodotoxin
Tetrodotoxin, also known as "tetrodox" and frequently abbreviated as TTX, sometimes colloquially referred to as "zombie powder" by those who practice Vodou, is a potent neurotoxin with no known antidote. There have been successful tests of a possible antidote in mice, but further tests must be...

 in the internal organs, especially the liver and the ovaries, but also in the skin
Skin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...

 and the testes. Therefore, only specially licensed chefs can prepare and sell fugu to the public, and the consumption of the liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...

 and ovaries is forbidden. But because small amounts of the poison give a special desired sensation on the tongue, these parts are considered the most delicious by some gourmets. Every year a number of people die because they underestimate the amount of poison in the consumed fish parts.

The poison paralyzes the muscle
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...

s while the victim stays fully conscious, and eventually dies from asphyxiation. There is currently no antidote
Antidote
An antidote is a substance which can counteract a form of poisoning. The term ultimately derives from the Greek αντιδιδοναι antididonai, "given against"....

, and the standard medical approach is to try to support the respiratory
Respiratory system
The respiratory system is the anatomical system of an organism that introduces respiratory gases to the interior and performs gas exchange. In humans and other mammals, the anatomical features of the respiratory system include airways, lungs, and the respiratory muscles...

 and circulatory system
Circulatory system
The circulatory system is an organ system that passes nutrients , gases, hormones, blood cells, etc...

 until the effect of the poison wears off.

The fish is also featured prominently in Japanese art
Japanese art
Japanese art covers a wide range of art styles and media, including ancient pottery, sculpture in wood and bronze, ink painting on silk and paper and more recently manga, cartoon, along with a myriad of other types of works of art...

 and culture.

Distribution

The 25 species belonging to the genus Takifugu (formerly known as Fugu, with the exception of one remaining Fugu species). Takifugu can be found worldwide from about 45° latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...

 north to 45° latitude south, mostly in salt water near coral reef
Coral reef
Coral reefs are underwater structures made from calcium carbonate secreted by corals. Coral reefs are colonies of tiny living animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. The polyps...

s or the shore, but some species also live in fresh water
Fresh Water
Fresh Water is the debut album by Australian rock and blues singer Alison McCallum, released in 1972. Rare for an Australian artist at the time, it came in a gatefold sleeve...

 or brackish water
Brackish water
Brackish water is water that has more salinity than fresh water, but not as much as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root "brak," meaning "salty"...

. Their diet consists mostly of algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...

, mollusks, invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...

s and sometimes crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s. All fishes in the tetradon family have strong teeth that may grow too long if the fish cannot consume abrasive food. Fugu can bite if provoked. Not all species are studied in detail, but the most researched takifugu is Takifugu rubripes, due to the commercial consumption and breeding of the fish. Takifugu rubripes, for example, breeds from March to May and lays eggs attached to rocks at a depth of around 20m. Fugu can also change color over time, and they get a darker or lighter color. This helps them to camouflage. A very dark color may be a sign of stress or illness.

Takifugu rubripes serves as a model organism
Model organism
A model organism is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the organism model will provide insight into the workings of other organisms. Model organisms are in vivo models and are widely used to...

 in biological research.

Morphology and behaviour

The pear-shaped Takifugu, like all pufferfish, are not fast swimmers as they mainly use their pectoral fins
Fish anatomy
Fish anatomy is primarily governed by the physical characteristics of water, which is much denser than air, holds a relatively small amount of dissolved oxygen, and absorbs more light than air does.- Body :...

 for propulsion, but they are very manoeuvrable and able to hover, swim backwards, and change direction much more quickly than most other types of fish. As a result, they are rarely found in open water and prefer to stay relatively close to the sea bed where they can explore complex environments such as oyster beds, seagrass meadows, and rocky reefs. Nevertheless, these fish are very curious and active, and in some cases even aggressive against other fugu or other fish. In the event of danger, the fish inflates itself by filling its extremely elastic stomach
Stomach
The stomach is a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract in some animals, including vertebrates, echinoderms, insects , and molluscs. It is involved in the second phase of digestion, following mastication .The stomach is...

 with water (or air when outside of the water) until the fish is almost spherical
Sphere
A sphere is a perfectly round geometrical object in three-dimensional space, such as the shape of a round ball. Like a circle in two dimensions, a perfect sphere is completely symmetrical around its center, with all points on the surface lying the same distance r from the center point...

 (hence the name blowfish or pufferfish).

Previously, it was unknown how pufferfish inflation took place. Recently, however, Dr. Peter Wainwright completed his analysis on the series of muscle actions which allow a pufferfish to inflate. First, the pufferfish fills its mouth with water. Then, it seals its mouth using a special valve at the bottom of the mouth. This valve flaps upward and covers the entire mouth of the fish. Next, a branchiostegal ray (a modified gill arch) pushes the water down the esophagus
Esophagus
The esophagus is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing, food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach...

 into the stomach. The extremely elastic stomach then expands. Depending on the species the fugu can achieve an almost perfect spherical shape.

Toxicity

The fish's main defense, however, is the neurotoxin
Neurotoxin
A neurotoxin is a toxin that acts specifically on nerve cells , usually by interacting with membrane proteins such as ion channels. Some sources are more general, and define the effect of neurotoxins as occurring at nerve tissue...

 contained in its internal organs, mainly the ovaries
Ovary
The ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in anatomically female individuals are analogous to testes in anatomically male individuals, in that they are both gonads and endocrine glands.-Human anatomy:Ovaries...

 and the liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...

, to a lesser extent in the intestines and the skin
Skin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...

, and only minute amounts in the muscle
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...

s and blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

. This makes the fugu a lethal meal for most predators, including the occasional human.

The toxin is called tetrodotoxin
Tetrodotoxin
Tetrodotoxin, also known as "tetrodox" and frequently abbreviated as TTX, sometimes colloquially referred to as "zombie powder" by those who practice Vodou, is a potent neurotoxin with no known antidote. There have been successful tests of a possible antidote in mice, but further tests must be...

, or more precisely anhydrotetrodotoxin 4-epitetrodotoxin and is about 1200 times deadlier than cyanide
Cyanide
A cyanide is a chemical compound that contains the cyano group, -C≡N, which consists of a carbon atom triple-bonded to a nitrogen atom. Cyanides most commonly refer to salts of the anion CN−. Most cyanides are highly toxic....

. This poison can also be found in other animals such as the Blue-Ringed Octopus
Blue-ringed octopus
The blue-ringed octopuses are three octopus species that live in tide pools in the Pacific Ocean, from Japan to Australia . They are currently recognized as one of the world's most venomous marine animals...

, cone snail
Cone snail
Conidae is a taxonomic family of minute to quite large sea snails, marine gastropod molluscs in the superfamily Conoidea.The snails within this family are sophisticated predatory animals...

s, and even some newt
Newt
A newt is an aquatic amphibian of the family Salamandridae, although not all aquatic salamanders are considered newts. Newts are classified in the subfamily Pleurodelinae of the family Salamandridae, and are found in North America, Europe and Asia...

s. The pufferfish does not create the poison itself; rather it is generated by 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...

 e.g. Pseudomonas
Pseudomonas
Pseudomonas is a genus of gammaproteobacteria, belonging to the family Pseudomonadaceae containing 191 validly described species.Recently, 16S rRNA sequence analysis has redefined the taxonomy of many bacterial species. As a result, the genus Pseudomonas includes strains formerly classified in the...

within the fish. The fish obtains the bacteria by eating food containing these bacteria. Pufferfish that are born and grown in captivity do not produce tetrodotoxin until they receive some of the poison-producing bacteria, often by eating tissues from a toxin-producing fish. Also, some fish are more poisonous than others. Each fish has enough poison to kill around thirty adult humans.

Genome

Apparently due to some unknown selection pressure
Natural selection
Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....

, intron
Intron
An intron is any nucleotide sequence within a gene that is removed by RNA splicing to generate the final mature RNA product of a gene. The term intron refers to both the DNA sequence within a gene, and the corresponding sequence in RNA transcripts. Sequences that are joined together in the final...

ic and extragenic sequences
Noncoding DNA
In genetics, noncoding DNA describes components of an organism's DNA sequences that do not encode for protein sequences. In many eukaryotes, a large percentage of an organism's total genome size is noncoding DNA, although the amount of noncoding DNA, and the proportion of coding versus noncoding...

 have been drastically reduced within this family. As a result, they have the smallest-known genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....

s yet found amongst the vertebrate
Vertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...

 animals, while containing a genetic repertoire very similar to other fishes and thus comparable to vertebrates generally. Since these genomes are relatively compact it is relatively fast and inexpensive to compile their complete sequences
Sequencing
In genetics and biochemistry, sequencing means to determine the primary structure of an unbranched biopolymer...

, as has been done for two species (Takifugu rubripes
Takifugu rubripes
Takifugu rubripes is a pufferfish in the genus Takifugu. A feature of this species is that it has a very small genome, which is used as a ‘reference’ for identifying genes and other elements in human and other vertebrate genomes...

and Tetraodon nigroviridis
Tetraodon nigroviridis
Tetraodon nigroviridis is one of the pufferfish known as the green spotted puffer. It is found across South and Southeast Asia in coastal freshwater and brackish water habitats. Tetraodon nigroviridis reaches a maximum length of about 15 cm...

).

Takifugu species table

Species of the Genus Takifugu
Species Author Common name Distribution Max. size Comments
Takifugu alboplumbeus Richardson, 1845 Komon-damashi (Japan) West Pacific 23 cm Poisonous, Salt Water
Takifugu basilevskianus? Basilewsky Darkgreen Puffer, Sansaifugu (Japan) ? ? Poisonous
Takifugu bimaculatus Richardson, 1845 Futatsuboshi-fugu (Japan) Northwest Pacific 30 cm Poisonous
Takifugu chinensis* Abe, 1949 Eyespot Puffer, Karasu (Japan) Northwest Pacific 55 cm Poisonous
Takifugu coronoidus Ni & Li, 1992 暈環多紀魨 (China) Northwest Pacific ? Not poisonous?
Takifugu chrysops* Hilgendorf, 1879 Red-eyed Puffer, Akamefugu (Japan) Northwest Pacific 20 cm Poisonous
Takifugu exascurus Jordan & Snyder, 1901 Mushifugu (Japan) Northwest Pacific 15 cm Poisonous
Takifugu flavidus Li, Wang & Wang, 1975 Towny Puffer, Sansaifugu (Japan), Hwang-jom-pok (Korea), Jú húng dong fang tún (China) Northwest Pacific 35 cm Poisonous
Takifugu niphobles
Grass puffer
The Grass Puffer is a species of fish in the Tetraodontidae family. It is found in Hong Kong, Japan, Taiwan, and Vietnam. It is often caught off beaches. docks, and piers using various baits such as worms, shrimp, Sea Lice, or cut fish...

*
Jordan & Snyder, 1901 Grass Puffer, Starry puffer, Kusafugu (Japan), Cá Nóc sao (Viet Nam) Northwest Pacific 15 cm Poisonous
Takifugu oblongus Bloch, 1786) Oblong blow fish, Lattice blaasop (India), Bebo (India) Buntal (Malaysia), Pita-pita (Indonesia), Ruitjies-blaasop (South Africa) West Pacific 40 cm Poisonous
Takifugu obscurus* Abe, 1949 Obscure Puffer, Mefugu (Japan) Western Pacific 40 cm Poisonous
Takifugu ocellatus Linnaeus
Carolus Linnaeus
Carl Linnaeus , also known after his ennoblement as , was a Swedish botanist, physician, and zoologist, who laid the foundations for the modern scheme of binomial nomenclature. He is known as the father of modern taxonomy, and is also considered one of the fathers of modern ecology...

, 1758
Ocellated Puffer Asia ? Poisonous
Fugu orbimaculatus Kuang, Li & Liang, 1984 圓斑多紀魨 (China) Asia ? Not Poisonous?
Takifugu pardalis* Temminck
Coenraad Jacob Temminck
Coenraad Jacob Temminck was a Dutch aristocrat and zoologist.Temminck was the first director of the National Natural History Museum at Leiden from 1820 until his death. His Manuel d'ornithologie, ou Tableau systematique des oiseaux qui se trouvent en Europe was the standard work on European birds...

&Schlegel,1850
Panther puffer, Higanfugu (Japan), Chol-pok (Korea), Bào wén dong fang tún (China) Northwest Pacific 30 cm Poisonous
Takifugu poecilonotus* Temminck & Schlegel, 1850 Fine Patterned Puffer, Komonfugu (Japan), Huin-jom-pok (Korea), Ban dian dong fang tún (China) Northwest Pacific 20 cm Poisonous
Takifugu porphyreus* Temminck & Schlegel, 1850 Purple Puffer, Namera-fugu (Japan), Mafugu (Japan), Kom-pok (Korea), Zi sè dong fang tún) (China) Northwest Pacific 52 cm Poisonous
Takifugu pseudommus Chu, 1935 Nameradafugu (Japan), Nameradamashi (Japan) Northwest Pacific 35 cm Poisonous
Takifugu radiatus Abe, 1947 Nashifugu (Japan) Northwest Pacific 20 cm Poisonous
Takifugu reticularis Tien, Chen & Wang, 1975 Reticulate Puffer, Amime-fugu (Japan) Northwest Pacific 29 cm Poisonous
Takifugu rubripes
Takifugu rubripes
Takifugu rubripes is a pufferfish in the genus Takifugu. A feature of this species is that it has a very small genome, which is used as a ‘reference’ for identifying genes and other elements in human and other vertebrate genomes...

*
Temminck & Schlegel, 1850 Torafugu (Japan), Tiger Puffer, Hóng qí dong fang tún (China), Cha-ju-pok (Korea) Northwest Pacific 70 cm Poisonous, Used in Chinese Medicine, Genome sequenced completely
Takifugu snyderi* Abe, 1988 Shosai-fugu (Japan) Western Pacific 30 cm Poisonous
Takifugu stictonotus* Temminck & Schlegel, 1850 Spotback, Spottyback Puffer, Gomafugu (Japan) Northwest Pacific 35 cm Poisonous
Takifugu vermicularis Temminck&Schlegel, 1850 Pear Puffer, Shosaifugu (Japan),, Nashifugu (Japan), Kuk-mae-ri-bok (Korea), Chóng wén dong fang tún (China) Northwest Pacific 30 cm Poisonous
Takifugu xanthopterus* Temminck & Schlegel, 1850 Yellowfin puffer, Shimafugu (Japan), Kka-ch'i-pok (Korea), Tiáo wén dong fang tún (China) Northwest Pacific 50 cm Poisonous

* Fish that have edible body parts according to the Japanese Ministry of Health and Welfare

See also

  • Fugu
    Fugu
    is the Japanese word for pufferfish and the dish prepared from it, normally species of genus Takifugu, Lagocephalus, or Sphoeroides, or porcupinefish of the genus Diodon. Fugu can be lethally poisonous due to its tetrodotoxin; therefore, it must be carefully prepared to remove toxic parts and to...

  • Pufferfish
    Pufferfish
    Tetraodontidae is a family of primarily marine and estuarine fish of the Tetraodontiformes order. The family includes many familiar species which are variously called pufferfish, balloonfish, blowfish, bubblefish, globefish, swellfish, toadfish, toadies, honey toads, sugar toads, and sea squab...

  • Tetrodotoxin
    Tetrodotoxin
    Tetrodotoxin, also known as "tetrodox" and frequently abbreviated as TTX, sometimes colloquially referred to as "zombie powder" by those who practice Vodou, is a potent neurotoxin with no known antidote. There have been successful tests of a possible antidote in mice, but further tests must be...

  • Culture of Japan
    Culture of Japan
    The culture of Japan has evolved greatly over the millennia, from the country's prehistoric Jōmon period to its contemporary hybrid culture, which combines influences from Asia, Europe and North America...

  • Cuisine of Japan
  • Fugu Plan
    Fugu Plan
    The Jewish settlement in Imperial Japan involved the movement of Jews to and through Japan to its occupied areas of China shortly prior to and during World War II, coinciding with the Second Sino-Japanese War...

  • Seafood
    Seafood
    Seafood is any form of marine life regarded as food by humans. Seafoods include fish, molluscs , crustaceans , echinoderms . Edible sea plants, such as some seaweeds and microalgae, are also seafood, and are widely eaten around the world, especially in Asia...


External links

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