Skip to main content

#3: Compound Eyes




Litinsects #3: Compound Eyes

I spy with my little eye. Eyes have evolved independently numerous times, which is why they vary so greatly in form and function depending on the organism (notice how I said organism and not specifically animal...? Well it depends on how eyes and sight are defined but animals are not the only life forms that can “see”). 

Insects 🐝 and their close relatives the crustaceans have COMPOUND EYES, which are these multi-faceted eyes that you’ve probably seen in flies... So how do they work?

  • Compound eyes are composed of units called OMMATIDIA, which are usually hexagonal in shape. A single ommatidium is like a mini eyeball: it contains photoreceptor cells, a lens, pigments, and an axon bundle that provides the animal’s brain with a small section of the picture that’s in front of it. The brain puts together the visual information from all ommatidia, forming just one image. So flies don’t actually see the world as a kaleidoscope like they sometimes show in movies
  • The number of ommatidia in an eye affects how detailed the image is. This number can range from a few (in silverfish) to around 30,000 (in dragonflies), depending on how important sight is to the insect’s lifestyle
  • Most compound eyes don’t see in very high resolution but are great at sensing RAPID MOVEMENT and come with a huge range of vision (almost no blind spots). That’s why flies always see you coming and are outta there before you can ever swat them
  • Insects usually can’t see the colors red and orange but many can see into the UV spectrum and even polarized light
Guess what? Insects actually have ANOTHER type of eye too! Be on the lookout 👀 for tomorrow’s post, where I’ll tell you all about it!
Labels:

Comments

Post a Comment

Popular posts from this blog

#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 ...
Post a Comment
Read more

#51: Mayflies

Litinsects #51: Mayflies Mayflies are aquatic freshwater insects and belong to one of the most primitive winged insect lineages! First off, what’s in a name? Mayflies’ common name comes from the fact that some species start “hatching” from the water in May. But their scientific name is much more interesting and accurate; this order is named EPHEMEROPTERA from the Greek “ephemera” for “lasting one day / temporary” and “pteron” for “wing”. A more fitting name would be dayfly, considering their adult lifespan... Most live less than 24 hours after emerging, the shortest adult lifespan of any insect! -Mayflies have triangular-shaped wings that are held upright over their bodies when at rest (sort of like a butterfly) and have three long tail-like filaments. These characteristics, both of which make them easily recognizable, are probably traits that were present in the most primitive flying insects -They are HEMIMETABOLOUS insects, meaning they go through incomplete metamorphosis, with multi...
Post a Comment
Read more

#39: Leaf cutter ants

© Gail Sumway  Litinsects #39: Leaf cutter ants You’ve likely seen them in nature documentaries; countless individuals on a trail with abstract leaf cut-outs on their backs... these are LEAF CUTTER ANTS. They can carry impressively heavy loads on their backs, up to 20 times their body weight. But have you ever wondered what they do with all these leaves that they carry back to their nests? You might assume that they eat them but they don’t! What they actually do is way cooler than that. Leaf cutter ants participate in a MUTUALISTIC SYMBIOSIS with fungi, a close relationship that benefits all parties. Ants cultivate underground fungus gardens in their nests and it’s actually the fungi that eat the leaves as they decompose. The fungus in turn serves as food for the ant colony! Because the fungus needs the ants to stay alive, it is a mutually beneficial relationship. Ants actively groom the gardens by removing parasites and even secrete anti-microbial substances to prevent growth ...
Post a Comment
Read more