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Whether it’s Pixar’s Dory with short-term memory loss, or the saying “he has the brain
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of a goldfish” - we’re constantly told that fish are simple and have poor memories.
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But are they more complex than we think?
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This is the Rotating Snake Illusion - as you move your eyes, the snakes appear to be moving
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in circles, but the image is actually stationary. It turns out that fish see this illusion in
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a similar way to you and I. Even though fish diverged from land vertebrates 450 million
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years ago, both have developed similar vision to hunt, escape predators, and avoid collisions.
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Researchers have hypothesized that we see the same motion illusions as a result of ‘convergent
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evolution’, where organisms not closely related independently evolve similar traits
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as a result of having to adapt to similar environments.
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Which of these red circles is larger? Your eyes are likely telling you the one on the
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right, and a fish would think so too. But it turns out they are the same size. In a
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study on redtail split fins, the fish were trained to discriminate between disks of different
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sizes and to prefer larger disks. And when presented with a similar illusion they chose
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the deceptively larger one.
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What about attention span? One particular report found that the human attention span
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is down from 12 seconds in the year 2000, to 8 seconds today. Our use of the internet
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and devices is theorized to play a role but, either way, goldfish have a 9 second attention
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span, trumping that of a human.
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When it comes to forgetfulness, a study using African Cichlids gave fish a food reward in
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a particular zone of an aquarium for 3 days in a row. Then, the fish were given a 12 day
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‘rest’ period before being reintroduced into the aquarium. Using motion-tracking software,
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the cichlids showed a distinct preference to the area of the aquarium where they had
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previously received a reward. Studies have even shown goldfish can remember things for
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at least 3 months; distinguishing between shapes, colours, sounds, and even navigating
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mazes. On top of this, goldfish can recognize their owners. Ultimately, fish have been shown
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to have quite good memories - after all they need to remember prey types, avoid predators
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and even avoid our hooks after being caught in the past.
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But when it comes to pain we’re actually quite different than fish. When you injure
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yourself, receptors in your body called ‘nociceptors’ send signals to the neocortex where the sensation
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of pain is processed. But many fish lack nociceptors and all fish lack a neocortex, so pain isn’t
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experienced in the same way.
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When Finding Nemo was first released, hundreds of fish were flushed to set them ‘free’,
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while in reality these fish often die from trauma or exposure to fresh water. Additionally,
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researchers worry that Finding Dory’s release could increase the decline in ornamental fish
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populations as more people will want the Royal Blue Tang as a pet.
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So we decided to make a video on 8 other Amazing Aquatic Animals on AsapTHOUGHT, where we visited
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an aquarium to check them out in person. Our lakes and oceans are full of some wild and
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beautiful creatures, so be sure to check it out with the link below!
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And Subscribe for more weekly science videos!