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Bombardier beetles are remarkable creatures, truly deserving the attention they have received. They earned their common name from their ability to defend themselves against predators by firing a mixture of boiling-hot toxic chemicals from special glands in their posterior. In at least one species, the spray even takes the form of a pulse jet. [Dean et al., 1990] (Other species spray an unpulsed stream; most species haven't been investigated so closely.)

The mechanism of their spray works thus: Secretory cells produce hydroquinones and hydrogen peroxide (and perhaps other chemicals, depending on the species), which collect in a reservoir. The reservoir opens through a muscle-controlled valve onto a thick-walled reaction chamber. This chamber is lined with cells that secrete catalases and peroxidases. When the contents of the reservior are forced into the reaction chamber, the catalases and peroxidases rapidly break down the hydrogen peroxide and catalyze the oxidation of the hydroquinones into p-quinones. These reactions release free oxygen and generate enough heat to bring the mixture to the boiling point and vaporize about a fifth of it. Under pressure of the released gasses, the valve is forced closed, and the chemicals are expelled explosively through openings at the tip of the abdomen. [Aneshansley & Eisner, 1969; Aneshansley et al, 1983; Eisner et al, 1989]

Much creationist literature gives an inaccurate account of the process. Based on an admittedly sloppy translation of a 1961 article by Schildknecht and Holoubek, [Kofahl, 1981] Duane Gish claimed that hydrogen peroxide and hydroquinones would explode spontaneously if mixed without a chemical inhibitor, and that the beetle starts with a mix of all three and adds an anti-inhibitor when he wants the explosion. [Weber, 1981] In fact, the two do not explode when mixed, as others have demonstrated. [Dawkins, 1987, p. 86-87] (Schildknecht did propose a physical inhibitor which kept the mixture from degrading in undisected beetles; in fact, the degradation he saw was probably simply a result of exposure to the air.) Gish still used the mistaken scenario after being corrected by Kofahl in 1978. [Weber, 1981] The same mistake is also repeated in books by Hitching in 1981, Huse in 1983 and 1993, and twice in a creationist magazine in 1990 [Anon, 1990a, b].

In a creationist children's book, Rue does a better job describing the chemistry but gets the physical mechanism wrong instead, saying the liquid shoots through the firing chamber and doesn't explode until outside the beetle. "If it exploded inside, it would blow any Bombardier Beetle to smithereens." [Rue, 1984, p. 23] In fact, it is because the explosion occurs inside the firing chamber that its force can be directed against a threat.

One must wonder how much weight an argument of design carries if the people making it don't know what the design looks like.

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