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Ocean Watch Susan Scott |
Caution wise near
all parts of a pufferfish"Can you site one example of tetrodotoxin poisoning caused by the bite of a puffer, any puffer?" a recent unsigned e-mail asked.
"If not, you should explain that the poison is in the bile attached to the liver and the flesh is harmless unless ... exposed to the bile."
This note referred to my recent column about using the sharp teeth of a dead pufferfish to cut a beached net. I didn't do it because I feared the fish's potent poison, tetrodotoxin. Apparently that irritated my reader.
It shouldn't have. He's wrong in thinking that pufferfish poison is confined to one place in the fish. In "Foodborne Pathogenic Microorganisms and Natural Toxins Handbook" (2003), the FDA reports that the gonads, liver, intestines, skin and flesh of pufferfish can contain levels of tetrodotoxin sufficient to produce rapid and violent death.
Or not. Some pufferfish contain no poison at all.
The reason for this variance is that pufferfish (and other animals) get their toxin from marine bacteria that manufacture it inside the fish. Several kinds of microbes make this deadly poison.
All occur naturally in warm sea water and estuaries throughout the world.
Among these are some bad-boy bugs: Vibrio species, some of which cause cholera and other lethal infections, and Pseudomonas, usually the source of the infection (among others) known as swimmer's ear.
Some pufferfish accumulate these natural, poison-producing bacteria while grazing on algae, invertebrates and decaying plants and animals. The fishes' four big teeth, which form a kind of beak, are ideal for scraping, crushing and cutting such food.
Tetraodontiformes, puffers' scientific name, refers to these remarkable teeth, tetra meaning four, odontos meaning tooth. Tetrodotoxin got its name from the fish.
The relationship between poison-producing bacteria and puffers is classic symbiosis. The fish, immune to the toxin, give the bacteria a mobile home in which to live, eat and reproduce.
In return, the bacteria churn out toxins that protect the fish. Predators generally leave the conspicuous, slow-swimming pufferfishes alone.
Count me in with those predators. I'll not test the toxicity of a pufferfish by cutting myself on its lip-covered teeth or skin-covered spines. And eating pufferfish is foolish.
Some people disagree with that, but this macho stand can prove fatal. Seven people have died in Hawaii from eating stripebelly pufferfish, also known as keke or o'opu hue.
In 2002, 10 people became ill after eating pufferfish caught in the Titusville, Fla., area. These cases were notable because previously, puffers from this area were safe to eat. Apparently, these fish fell in with the wrong crowd of bacteria.
All of the Florida victims lived, but only because some had emergency help breathing.
In 1996, three chefs got sick from eating pre-packaged, ready-to-eat pufferfish imported from Japan by a co-worker. All three went to the emergency room by ambulance and survived.
Pufferfish poisoning in Japan affects 30 to 100 people per year, most from home-prepared meals. Some of these victims die.
Medieval Europeans believed that excess bile, a fluid excreted by the liver into the digestive tract, made people irritable. That's silly. Avoiding pufferfish, however, is not.
See the Columnists section for some past articles.
Marine science writer Susan Scott can be reached at http://www.susanscott.net.