A Taste for the Toxic
Swelling up like a balloon is a pretty dramatic
defense mechanism, but many species of pufferfish
pack an even deadlier weapon - poison.
This poison is called tetrodotoxin, a word coined
after the puffer fish's scientific name. It's a potent
neurotoxin that can kill even humans when ingested.
Though this toxin was first identified in puffers, the
fish don't actually make it themselves - in a way, they
borrow it.
Tetrodotoxin is originally produced by marine bacteria.
It travels up the food chain when microorganisms,
such as plankton, consume the bacteria. These
creatures are, in turn, eaten by larger animals, and
some of these - such as snails, marine worms and
starfish - are favorite foods of pufferfish.
How can puffers handle ingesting this deadly
neurotoxin? Scientists have found that puffers are
resistant to tetrodotoxin because the sodium channels
of their muscle tissue are genetically different from
those of other fish. Puffers even have a special toxinuptake
mechanism in their liver that transfers toxin into
their bloodstream. After accumulating toxin through
their food, puffers can secrete the toxin through their
skin and into the mouth of an unlucky predator.
Despite their toxin-hoarding ways, puffers are
considered a desirable dinner item in some parts
of the world. Some poisonous puffers can be eaten
when prepared carefully, but there's another way
around the problem: rendering the fish non-toxic by
eliminating tetrodotoxin from their diets. Japanese
fish farmers use this strategy by raising pufferfish in
cages or land-based aquaculture systems. That's a
lot less risk on the dinner plate!