Pufferfish

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iPuffer fish

White-spotted puffer, Arothron hispidus

Scientific classification

Kingdom:	Animalia
Phylum:	Chordata
Subphylum:	Vertebrata
Class:	Actinopterygii
Order:	Tetraodontiformes
Family:	Tetraodontidae

Genera

Amblyrhynchotes
Arothron
Auriglobus
Canthigaster
Carinotetraodon
Chelonodon
Colomesus
Contusus
Ephippion
Feroxodon
Fugu
Gastrophysus
Javichthys
Lagocephalus
Liosaccus
Marilyna
Monotretus
Omegaphora
Pelagocephalus
Polyspina
Reicheltia
Sphoeroides
Takifugu
Tetractenos
Tetraodon
Torquigener
Tylerius
Xenopterus
For species see Genera articles.

The puffer fish, also called blowfish, swellfish, globefish, balloonfish, bubblefish are fish making up the family Tetraodontidae, within the order Tetraodontiformes. They are named for their ability to inflate themselves to several times their normal size by swallowing water or air when threatened; the same adaptation is found in the closely related porcupinefish, which have large conspicuous spines (unlike the small, almost sandpaper-like spines of puffer fish). The scientific name, Tetraodon, refers to the fact that they have four large teeth, fused into an upper and lower plate, which are used for crushing the shells of crustaceans and mollusks, their natural prey. They also enjoy the occasional bloodworm. Female pufferfish lay huge numbers of eggs, up to 200,000 per fish. The tiny, orange eggs stick to each other and settle to the bottom in huge masses. They hatch in about five days. When first born the larvae are brightly colored and begin feeding three days after they hatch. Young puffers are capable of inflating at seven days old when they are less than a half-inch long.

The eyes and internal organs of most puffer fish are highly toxic, but nevertheless the meat is considered a delicacy in Japan and Korea. The name "fugu" is used both for the fish that are eaten and for their meat (for more details see Fugu). The Korean term for this fish is "boh-guh" fish.

There are 185 known species of the family Tetraodontidae, of which 38 can be found in Japan. They can be found worldwide from about 45° latitude north to 45° latitude south, mostly in salt water near coral reefs or the shore, but some species also live in fresh water and brackish water.

Tetrodotoxin is a powerful neurotoxin that can cause death in nearly 60% of the humans that ingest it. A human only has to ingest a few milligrams for a fatal reaction to the toxin to occur. Once consumed the toxin blocks the sodium channels in the nervous tissues, ultimately paralyzing the muscle tissue. Curiously, the toxin seems not to be synthesized by the fish itself, but by bacteria associated with the fish. The fish has a mutation in its own sodium channels which makes it resistant to the effect of the toxin.

1 Natural defenses
- 1.1 Puffer fish toxin
- 1.2 Puffer fish poisoning
2 Location
3 Other facts
4 Trivia
5 References
6 External links

[edit] Natural defenses

The puffer fish's unique and distinctive natural defenses are necessary due to their particular form of locomotion. Puffer fish use a combination of pectoral, dorsal, anal, and caudal fins for propulsion that make them highly maneuverable but very slow, and therefore comparatively easy targets for predators. As a defense mechanism, puffer fish have the ability to inflate rapidly, filling their extremely elastic stomachs with water (or air when outside the water) until they are almost spherical in shape. Thus, a hungry predator stalking the puffer fish may suddenly find itself facing what seems to be a much larger fish and pause, giving the puffer fish an opportunity to retreat to safety.

Some puffer fish also produce a powerful neurotoxin in their internal organs, making them an unpleasant, possibly lethal, meal for any predatory fish that eats one. This neurotoxin is found primarily in the ovaries and liver, although smaller amounts exist in the intestines and skin, as well as trace amounts in muscle tissue and in its blood. Many puffer fish have bright colors and distinctive markings and make no attempt to hide from predators. This is likely an example of aposematism, where the puffer fish advertises to potential predators that it is not safe to eat. Obviously being poisonous does not help the puffer fish once it has been eaten, so the evolutionary mechanism at work benefits the species, with predators learning that puffer fish are at least distasteful and probably sickening, and so avoided next time that predator encounters that species of puffer fish.

It should be noted that puffer fish toxin is not necessarily as toxic to other animals as it is to humans, and some species of fish routinely eat puffer fish, such as lizardfish [1] and tiger sharks [2]. Puffer fish toxin evolved as a response to aquatic predators such as larger fish, rather than for use against humans. Note also, not all puffer fish are poisonous; Takifugu oblongus, for example, is one of the fugu puffer fish that is not poisonous.

Image:Puffy Feb 2006 small.JPG

[edit] Puffer fish toxin

Puffer fish toxin is called tetrodotoxin, or more precisely anhydrotetrodotoxin 4-epitetrodotoxin. It is also found within other animals such as the Blue-Ringed Octopus, Cone Snail, and in certain varieties of newt. Tetrodotoxin is produced within the puffer fish by bacteria, which are acquired through food. This means that puffer fish raised in captivity do not contain tetrodotoxin, and therefore are not poisonous until they come into contact with the bacteria. The puffer fish itself has immunity to the poison due to a mutation in the protein sequence of the sodium channel pump on the cell membranes.

Tetrodotoxin is an exceptionally lethal poison. Tetrodotoxin is approximately 1200 times deadlier than cyanide. In animal studies with mice, 8 mg tetrodotoxin per kilogram of body weight killed 50% of the mice (see also LD50). It is estimated that a single puffer fish has enough poison to kill 30 adult humans.

[edit] Puffer fish poisoning

Puffer fish poisoning usually occurs as a result of accidental consumption of fish or meat tainted with puffer fish. Treatment consists of supportive care and intestinal decontamination with gastric lavage and activated charcoal. Case reports suggest that anticholinesterases such as edrophonium may be effective.

Saxitoxin, the cause of PSP (paralytic shellfish poisoning, red tide), can also be found in puffer fish. Cases of neurologic symptoms, including numbness and tingling of the lips and mouth, have been reported to arise rapidly after the consumption of puffer fish caught in the area of Titusville, Florida. These symptoms are generally resolved within hours to days, although one affected individual required intubation for 72 hours. As a result of such cases, Florida banned the harvesting of puffer fish from certain bodies of water.

A drug called Tectin that is derived from tetrodotoxin is being developed as a potent pain reliever. Administered in very small quantities it can bring relief to those suffering from intense chronic pain, such as that experienced by some cancer patients. Other uses, such as helping opiate addicts through withdrawal, are also being studied.

[edit] Location

Coming from all over the world, it can sometimes be difficult to find the blowfish’s origin. It is found in the Pacific and Atlantic Oceans; certain species can also be found in freshwater streams and rivers.

[edit] Other facts

Image:Black-spotted.puffer.arp.jpg

Due to some unknown selection pressure, intronic and extragenic sequences have been drastically reduced within this family. As a result, they have the smallest-known genomes yet found amongst the vertebrate animals, while containing a genetic repertoire very similar to other fish and thus comparable to vertebrates generally. Since these genomes are relatively compact it's relatively fast and inexpensive to compile their complete sequences, as has been done for two species (Takifugu rubripes and Tetraodon nigroviridis).

Puffer fish are also one of few kinds of fish that can blink or close their eyes.

Puffer fish are able to move their eyes independently, and many species can change the color or intensity of their patterns in response to environmental changes. In these respects they are somewhat similar to the terrestrial Chameleon.

[edit] Trivia

Puffy the puffer fish has been designated as the mascot of the OpenBSD project.
Bloat, voiced by Brad Garrett, is a puffer fish in Finding Nemo.
Sykes, voiced by Martin Scorsese, is a puffer fish in Shark Tale.
Dolphins have been observed using puffer fish as a sort of toy in the wild. They tease the puffer fish with their teeth, causing the small fish to become alarmed and then inflate. After a while the fish calms down and deflates, thus starting the cycle over again. It is speculated that dolphins may also enjoy the mild numbing effect from small amounts of the puffer fish toxin.
The covers of the books "Understanding Japanese Information Processing" and "Understanding CJKV Information processing" by Ken Lunde, published by O'Reilly, feature an engraving of a puffer fish.
When lifted out of water, puffer fish can inflate with air, but they may have problems deflating again afterwards. When this happens with aquarium specimens, fishkeepers hold the puffer underwater by the tail, head upwards, and shake the fish gently until the air escapes out of the mouth.

[edit] References

Arreola, V.I., and M.W. Westneat. 1996. Mechanics of propulsion by multiple fins: kinematics of aquatic locomotion in the burrfish (Chilomycterus schoepfi). Proceedings of the Royal Society of London B 263: 1689–1696.
Ebert, Klaus (2001): The Puffers of Fresh and Brackish Water, Aqualog, ISBN 3-031-70260-X
Gordon, M.S., Plaut, I., and D. Kim. 1996. How puffers (Teleostei: Tetraodontidae) swim. Journal of Fish Biology 49: 319–328.
Plaut, I. and T. Chen. 2003. How small puffers (Teleostei: Tetraodontidae) swim. Ichthyological Research 50: 149–153.