#5: How do grasshoppers hear?

Litinsects #5: How do grasshoppers hear?

Can grasshoppers hear? Yes! As a matter of fact, any animal that uses acoustic signals to communicate must have organs to pick up these signals, otherwise what’s the point? Animals may use sound to detect predators, localize prey, and/or find mates, which is the case in grasshoppers as well. But their ears 👂 are very different than the ones sticking out from the side of your own head right now...

🦗 Grasshoppers and some other kinds of insects hear using a TYMPANUM (or tympanal organ) which is basically a structure like the human eardrum.
Real quick, the basics: Sound is made by waves that cause the surrounding molecules (usually air but it could also be another medium) to vibrate. Hearing is the perception of sound through the detection of these vibrations. Thus, in order to hear, some sort of auditory organ must detect vibrations in the surrounding medium and change them to nerve impulses that can be sent to the brain for processing 🎧

Now for some fun facts about tympanal hearing:

Tympanal ears consist of a thin but tough EXTERNAL MEMBRANE that picks up vibrations in the air (similar to a drum head 🥁), an air-filled sac beneath it, and a sensory organ to send this info to the brain

Tympanal organs are thought to have appeared independently in several different groups of insects. Their structure and position vary and can be used to determine the classification of a species

In grasshoppers the tympanum is rather conspicuous and easy to identify (though it is protected from view a bit by the wings) but in other insect groups it may be smaller or hidden from view entirely

Insect “ears” can be found at a bunch of different locations on the body depending on species, such as on the legs, on the abdomen, even on the wings... but almost never on the head!

Hearing organs in insects are usually specialized to pick up certain frequency ranges that are most vital to the individuals. For example, species that use mating calls will have ears that are specialized to hear the frequency of a potential mate’s call. Some insect hearing is specialized to pick up the calls of OTHER species, either prey they are searching for or predators they are

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