• Question: why do shrimps not have pupils?

    Asked by evilhamsters12 to Claire, Joanna, Kapila, Renata, Suzanne on 26 Jun 2013.
    • Photo: Claire El Mouden

      Claire El Mouden answered on 26 Jun 2013:

      Hiya,

      Natural selection has ‘rediscovered’ things like eyes and wings on several occasions during the history of life. In each case, the way it’s made it possible for animals to see is a little bit different. So humans and all other vertebrate share the same basic eye design as their common ancestor had simple eyes, but invertebrates (like shrimp) evolved eyes separately.

      That is why you get a diversity of eye designs – for example many insects have compound eyes (masses of tiny lenses), spiders have 8 eyes, extinct trilobites from the Phacops family had eyes made of solid crystal!!!

      Shrimp and lobsters have an eye design that is based on reflecting light into a central point (i.e. bouncing off a shiny surface). Vertebrate eyes, by contrast, refract light (bending it into focus by making it pass through something transparent). Apparently by studying lobster and shrimp eyes, and understanding how they concentrated beams of light, astronomers were able to invent a better telescope design!

    • Photo: Suzanne Harvey

      Suzanne Harvey answered on 27 Jun 2013:

      I had to look this one up, but when I was looking I came across an article saying that mantis shrimps have the most complex eyes in the animal world, more complex than our own! They have ‘pseudo-pupils’ that are similar to ours, and apparently they can judge the depth of an object in water with just one eye, while we need two to judge how far away something is.

      Thanks for the question, I’ve learnt something new today 🙂

    • Photo: Renata Medeiros

      Renata Medeiros answered on 28 Jun 2013:

      Alternative answer -because they don’t have shrimp schools! LOL

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