Saturday, August 1, 2009

The Dangerous Puffer Fish

Recently, I'd talk about underwater Mexico which has many puffer fishes. So, the puffers are so cute and beautiful, some people like to feed them in aquarium because they can scalable their body when scaring, it look funny in the fish tank. The Puffer fish are the second most poisonous vertebrate in the world, the first being a Golden Poison Frog. The skin and certain internal organs of many tetraodontidae are highly toxic to humans. There unique and distinctive natural defenses are a compensation for their particular form of locomotion. Puffers 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.

Puffer Fish

As a defense mechanism, puffers 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 puffers may suddenly find itself facing what seems to be a much larger fish and pause, giving the puffers an opportunity to retreat to safety. When lifted out of water there is a risk that puffers inflate with air. This may result in problems deflating again afterwards.

When this happens with aquarium specimens the recommended course of action for fishkeepers is to hold the puffer underwater by the tail, head upwards, and shake the fish gently until the air escapes out of the mouth. Some puffers also produce a powerful neurotoxin called tetrodotoxin 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.

The puffer's poison is made by bacteria of the genus vibrio and may actually enter the fish by consuming prey that does possess the poison already. Most puffers are drab, many have bright colors and distinctive markings and make no attempt to hide from predators. This is likely an example of aposematism. 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. Puffers 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. Since these genomes are relatively compact it is relatively fast and inexpensive to compile their complete sequences.

Fugu
Photo: sushifaq.com

Puffer's toxin evolved as a response to aquatic predators such as larger fish, rather than for use against humans. Note also, not all puffers are poisonous; Takifugu oblongus, for example, is one of the fugu puffers that is not poisonous. However, it should be noted that puffer's neurotoxin is not necessarily as toxic to other animals as it is to humans, and puffers are eaten routinely by some species of fish, such as lizardfish and tiger sharks. Puffer poisoning usually results from consumption of incorrectly prepared puffer soup, chiri or occasionally from raw puffer meat, sashimi fugu. While chiri is much more likely to cause death, sashimi fugu often causes intoxication, light-headedness, and numbness of the lips, and is often eaten for this reason.

Puffer's poisoning will cause deadening of the tongue and lips, dizziness and vomiting. These are followed by numbness and prickling over the body, rapid heart rate, decreased blood pressure and muscle paralysis. Death results from suffocation as diaphragm muscles are paralyzed. Patients who live longer than 24 hours are expected to survive, although the poison can cause comas lasting several days. Many people report being fully conscious during the entirety of the coma and can often remember everything that was said while they were supposedly unconscious. So, if you diving to found them, just keep away from them.

Source: wikipedia.org

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