Antennation

Insect antennae are sophisticated organs that can perform many functions for insects:

• Olfaction (smell)
• Gustation (taste)
• Mechanoreception (feeling)
• Hygroreception (humidity detection)
• Thermoreception (temperature)

Basically, antennae can do everything but see. They play powerfully in orientation of the insect in space; detecting wind speed and direction, the smell of pheromones in the air leading them to a mate, or the subtle vibration of prey below the bark of a tree. What is interesting to me is that antennae have so many different forms. Termites have simple moniliform antennae like tiny strings of tiny beads. Silkmoth and mosquito males have elaborate bipectinate plumose antennae. My small hive beetles have adorable club-shaped antennae which make them look like Mickey Mouse when they hold their antennae up. The antennae of house flies are two fat dangly bulbs with a single feather mounted at the top of each. The antennae of scarab beetles terminate in a fan-like array of delicate fingers called lamellae that can be spread open or closed tightly like a fist and tucked away into cavities under the insect's head. Dragonflies have nothing but two short bristles for antennae. Dizzying variety is the rule when it comes to antennal form. So why so many types? Does each of them correspond to some special life-style like insect leg types?


Question of the day:

Why are there so many types of insect antennae?

Answer:

Dunno.

No, seriously- we don't know why there are so many types of insect antennae. Generally, where olfaction is important, we find more elaborate or specialized antennae, such as those of male moths. Dragonflies, on the other hand, hunt primarily by sight, and thus may be forgiven for having simple and uninteresting antennae. Evolution seems to have favored divergence in most cases and convergence in a few like the elbowed antennae of weevils and ants. Beyond that, antennae are as diverse as the insects themselves. Family resemblance in the antennae is quite useful for classifying insects, but why scarab beetles have fancy lamellate fingers and small hive beetles small club-shaped antennae is rather a mystery.

Some questions in biology will always be easier to answer with "It's for decoration" or "Because that's how God made him." And perhaps in a sense, this is true- that God has seen fit to elevate diversity over uniformity, and style sometimes seems to trump function. But as we scientists study and search for a function for strange traits and find that they do, indeed, have a function, are we disappointed? On the contrary, when fascinating form and amazing function come together we get a new sort of joy- beyond the joy of beauty and the joy of a well-made machine. It is the joy of something that is, on all accounts, very good - just as the creator said it was.