What Are the Parts of the Bombardier Beetle?

Body Structure

• Beetles are insects, meaning they have three body regions: the head, thorax and abdomen. The head is at the front and features the mouth and feelers. The thorax goes from the back of the head to the hind legs of the beetles. The wings are also attached to the thorax. Beetles don't use their front wings, called elytra, for flying. Many beetles use these front wings as a shell, but others do not. The hind wings are used for flying. Most species of bombardier beetles use their elytron as a partial shell, covering only the back of the thorax and the abdomen. This makes them resemble ear wigs. The legs are also attached to the thorax and include the coxa, trochanter, femur, tibia and tarsus, from front to back. The abdomen is the back of the beetle, containing the anus.

Specialized Parts

• The bombardier beetle has a special section in its abdomen called the reaction chamber. It also has two separate storage chamber for hydroquinone and hydrogen peroxide. These specialized defensive body parts are located in the abdomen at the back of the beetle. They are connected by tubes, with the containment chamber being attached directly to the anal cavity of the beetle. The chemicals in the storage chambers are kept separate and safely unmixed until the bombardier beetle feels threatened by a predator or any situation.

Defensive Reaction

• When threatened, the bombardier beetle injects these two chemicals into the reaction chamber. The chamber contains catalse and peroxidase. Catalase breaks the hydrogen peroxide down. This creates water and oxygen. The perioxidase turns the hydroquinone into a different chemical called benzoquinone. These chemicals are not combustible inside of the combustion chamber. They only become combustible when the beetle expels the gas out of its anus. The chemicals then react with air causing a small explosion and a puff of smoke. This creates a startling sound and a rancid smell that helps to scare away most predators.

The Debate

• Creationists use the bombardier beetles as an argument against evolution. According to Talk Origins, a random evolution could not have created a defensive system so potentially threatening without destroying an animal unprepared to control it. The chemicals inside could potentially cause the beetle to explode if not expelled in instinctually controlled bursts. They also argue that the beetles' defensive mechanism is too accurate. According to the Ecological Society of America, African bombardier beetles have been tested to spray in a 270-degree radius. However, Talk Origins reports that evolutionists argue that they have found beetles around the world that contain at least one section of the defensive mechanism, such as a container for hydrogen peroxide. These beetles do not have the entire defensive mechanism.