Sphyraena barracuda
King of the Reef


    While barracuda frequently interact with many fish species as a predator, they engage in several other types of interactions that are less well known.

    The great barracuda spends much of its life just floating in the water, but during this time it is taking part in a mutualistic relationship with a little fish known as the cleaner wrasse (shown in the image at the right).The barracuda sits in the water with its mouth partly open and its gills flared to allow the wrasse to eat off dead skin andImage from Wikipedia parasites. This relationship could even be considered obligate mutualism because without the wrasse, the barracuda's gills would be clogged with dead skin and without the barracuda, the wrasse would have no source of food.

    Many people wonder if this fierce predator also takes bites out of humans. Although there have been several barracuda attacks on humans, for the most part these creatures do not strike unless provoked. In reality, habitat destruction by humans poses a greater threat to the barracuda than it does to us. The one main danger associated with the great barracuda is ciguatoxin, a toxin commonly found in barracuda flesh, which causes human ciguatera fish poisoning. The effects of poisoning are gastrointestinal, neurological, and cardiac symptoms; sometimes these neurological symptoms can be very strange, such as the reversal of hot and cold sensations. The suspected cause of ciguatoxins is a dinoflagellate species, Gambierdiscus toxicus, which releases toxins that are bioaccumulated so that the highest concentration of toxins is found in the highest trophic levels, namely, the great barracuda. Barracuda were once sought after for their meat, but consumers are now strongly cautioned not to eat barracuda because of the health problems that are associated with ciguatoxins. Barracuda have been used in research studies dealing with these toxins and have proved very helpful in tracking and understanding ciguatoxin. Increasing studies will allow us to better detect toxic areas and to improve the management and treatment of human ciguatera fish poisoning.

Image from NOAA Photo Library

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