This question may sound stupid, but I once read that some bacterias can be 0.5mm long, making them visible to the human eye. Proportionally, this bacteria would be huge next to an insect like a fruit fly, hence my question.
This question may sound stupid, but I once read that some bacterias can be 0.5mm long, making them visible to the human eye. Proportionally, this bacteria would be huge next to an insect like a fruit fly, hence my question.
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If they had similar eyes to us, then yes. However, most insects have compound eyes. These consist out of thousands of tiny tubes which capture tiny fragments of its surrounding and makes them able to react more quickly and have a full view of its surrounding.
Their image resolution, however, is quite poor and this is the trade off for being able to see their complete surrounding more quickly than we do and can also observe UV and polarized light. So, in principle no they don’t due to their lower reliance on visual sensory input.
insects generally have rather poor spatial vision. jumping spiders, though, can have excellent spatial vision, some of them have acuity comparable to cat vision (seeing details as small as ~0.1 degrees of visual angle – for comparison, normal human spatial vision, at its best, can resolve details as small as ~0.03 degrees).
supposing a jumping spider is looking at something a centimeter in front of its face (kind of like a human looking at something a couple of meters away), it would be able to resolve details as small as ~17 microns, which is pretty small. this is close to the size of typical bacteria, red blood cells – both of which would be at the very limit of the spider’s acuity – and lots of other things that we need a microscope to see. (edit to be a little clearer on this point: to a spider with good vision, bacteria or cells could be visible in the same way that grains of sand are visible to you – as tiny particles without much or any detail)
https://en.wikipedia.org/wiki/Micrometre
As a very general oversimplified rule of thumb, seeing smaller details requires larger eyes to make the lens more powerful. Your own body being smaller, or closer to the scale of the thing you’re looking at, doesn’t really help you focus light to resolve an image.
In theory smaller cells in the retina could increase the resolution by allowing the light from some feature of an object to fall across more cells. But smaller animals tend to have fewer cells rather than smaller ones.