Basic Information
An insect is any one of a large class of arthopod animals found in most environments on earth. The many different species of insects have in common a division of the body into three parts1 - head, thorax and abdomen - six legs connecting to the thorax, compound eyes and one pair of antennae. Being arthopods they also possess an exoskeleton.
Internal arrangements are generally quite rudimentary - the body is filled with a (usually yellowish) fluid matrix called haemolymph (since it fulfills the functions of both blood and lymph in higher animals), a primitive central nervous system, a simple gut and a heart like organ which circulates the haemolymph. Breathing is through vents in the body known as spiracles which let on to simple ducts in contact with the haemolymph.
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Some Types of Insect
Insects in the News
- News: Ant mega-colony takes over world
- News: Zombie Fire Ants
- News: Zombie caterpillars controlled by voodoo wasps
- News: Zombie Cockroaches Revived By Brain Shot
Sources
Game and Story Use
- The simple respiratory system via spiracles relies on diffusion to introduce oxygen to the haemolymph. Diffusion like this only works across very small scales, which is why most insects are pretty small. In a more highly oxygenated atmosphere, such as we had on earth in the primordial past, larger insects were viable. So if you have really large insects or insect-like critters in your setting, you may want to explain that in some way. It depends a lot on where your setting lands on the mohs scale of sci-fi hardness and the exact nature of the big bugs you're introducing.
- Something created by magic may already handwave the problem aside.
- An alien invasion probably has insect-like critters with more advanced alien biology including organs is more like a lung than a spiracle.
- That could be part of the balance of power on a galactic scale, with the insect-people only being interested in planets with a particular atmospheric condition that works for them, and humans taking the planets with air more like our own. Either side can don a spacesuit to visit the other, but the value of the real estate is at least partly a function of the safety precautions needed by a given species to live on a given world.
- So the problem really only comes up if your game is mostly realistic, but needs a big insect in a hurry without much time for evolution to do its trick. You can't just douse an anthill with radiation and get giant insects the next day, at least not outside of a context where you're purposefully trying to emulate the bad science of 1950s sci-fi B-movies, because science does not work that way.
- That said some sort of "growth ray" that mostly just produces dead insects, or short-lived very panicked insects, could have some morbidly unique story potential.
- Insects are creepy-crawly, so they are a good match for horror genre. Dead bodies covered in insects or their larva. Giant swarm clouds of locusts devouring everything in their path. Small awful critters with a dangerous venom. Parasitic wasps who try to implant their eggs under your skin. Nasty stuff.