#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

Comments

#13: Insect Legs

Litinsects #13: Insect Legs Insect legs can be as diverse as the animals themselves. Some are long and slender like a crane fly’s, some are short and hefty like a mole cricket’s. But what all insects share is the number and layout of those legs. Hexapods have 6 LEGS, a pair each of fore, mid, and hind legs that are made up of the same basic units. Starting closest to the body, they are: (1) the coxa, which attaches the leg to the thorax (2) the trochanter (3) the femur, which is oft en the thickest segment (4) the tibia, often covered in tiny hairs (5) the tarsus, which contains 5 “pseudo-segments” (6) the pretarsal claws, of which most insects have 2 on each leg The basic units of the leg always occur in this order but may be reduced or highly modified in some species to fit certain tasks such as running, digging, swimming, grasping, or jumping. This photo sums it up perfectly: from < https://wiki.bugwood.org/File:Insect...

#4: Simple Eyes

Litinsects #4: Simple Eyes Yesterday I talked about compound eyes, the multi-faceted structures that most insects use to see the world 👀 But insects actually have another visual system as well, composed of simple eyes or OCELLI. Unlike compound eyes, ocelli are composed of only one structure which makes them comparatively “simple” although they are still very important. These are light-detecting organs consisting of a single lens with sensory cells. They can detect movement but don’t form complex images. “Ocellus” comes from the Latin word oculus, meaning eye. So these structures are literally “little eyes” Ocelli are located on the insect’s head, usually between or adjacent to the compound eyes. They are usually dome-shaped, somewhat shiny structures In most flying insects (such as flies, dragonflies, bees, etc.) there tend to be three ocelli in a triangle arrangement (see photo). Some terrestrial insects (like cockroaches) have only two ocelli ...

#22: Caterpillars

Litinsects #22: Caterpillars Since you are freshly familiar with metamorphosis from my last posts, I will today be talking about caterpillars 🐛 and some structures that change drastically in appearance from before to after metamorphosis: legs. Caterpillars are the worm-shaped larval stage of butterflies and moths. They have huge appetites; they mainly feed to grow and gain energy for their transformation into adulthood. In order to do this they need to get around, for which they use le gs because only adult stages have wings. But insects only 3 pairs of legs, right? So where do all these extra legs come from all down the sides of their bodies? Caterpillars have 3 pairs of TRUE LEGS, attached to their thorax, which are jointed and have little claws on the end. These legs are still present after metamorphosis, though they will have changed substantially Additionally, they usually have 2 to 5 pairs of PROLEGS, which are protrusions fr...

Litinsects

Search This Blog