Myth Busting Monday: Goldfish Memory

myth busting Monday - goldfish wearing a mortar board

Happy Myth Busting Monday! Ichthyophiles, it’s your day – today we dispel a tenacious myth about one of your favourite creatures…

Myth: Goldfish have a three-second memory

Truth: Goldfish, and most other fish officially studied, have been shown to have memories extending far past the three-second barrier. Fish intelligence, cognition and sentience has been studied extensively over the years, often using the classical conditioning techniques popularised by the scientist Ivan Pavlov and his many well-trained dogs. In one type of study, fish that were fed at one end of their tank in the morning, and the other end in the evening, started to gather at the correct ends in anticipation of feeding time. This showed that they could make associations between locations, times and rewards.

If you have your own fish, this type of study is very easy to replicate (and please let us know about it if you do!). In fact, in 2008 a 15-year-old student named Rory Stokes decided to debunk the goldfish memory myth for himself. He put a red Lego block into his fish tank each day and sprinkled the food around it. After just three weeks, Rory found that the fish would start to gather around the red Lego block before he had put the food in. He also found that the fish still associated the Lego with being fed even after a week of Lego-free meals.

It’s almost certainly a good thing that fish can remember things for more than three seconds. A memory this short would be of little to no use to a living creature that had to find itself food, avoid predators, and otherwise survive from day to day.

So where did the myth come from? It’s possible that it was invented by purveyors of pet fish, to make everyone feel better about keeping fish in small uninteresting environments. It’s also possible that pet fish’s repetitive behaviours were interpreted as the fish ‘forgetting’ what it had already done, although repetitive behaviour in a captive animal usually indicates that the animal is somehow distressed. So if you do have pet fish, keep their minds active by making sure that their tank is interesting and stimulating – it’s best to consult fish-keeping experts for the best ways to do this!

P.S. If you’re someone who regularly employs the ‘memory like a goldfish’ simile to describe someone’s (or your own) poor memory, might we suggest switching to ‘memory like a sieve’? Sieves have indeed been scientifically proven to let many things through them.

P.P.S. An ichthyophile is one who loves fish. #todayilearned

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Myth Busting Monday: Breathing Trees

It’s Myth Busting Monday time! This is one that has many variations, all with a seed of truth… 

Myth: Plants breathe CO2 during the day, and oxygen during the night

Truth: OK, so this is almost right. Plants do indeed ‘breathe’ or take up carbon dioxide (CO2) when the sun is shining, because they use it to make sugars in a process called photosynthesis (‘oh, I’ve heard of that!’).

Photosynthesis converts sunlight and CO2 into sugars found in plants, and produces oxygen as a by-product. Photosynthesis is ultimately the oxygen and food source of every living being on the planet…but of course, it can only happen while the sun is shining.

Speaking of every living being on the planet, there’s another process that goes on in all their cells – it’s called cellular respiration, and it converts oxygen and sugars into energy that can be used by their cells. Carbon dioxide is a by-product of this process.

Plants are awesome because they do both these processes. During the day while they’re photosynthesising, they don’t need to take up oxygen from the atmosphere because they’re producing so much of it already. But they do need to take up oxygen at night time to complete the cellular respiration process. Luckily for us, they produce about 10 times the amount of oxygen they use themselves.

So trees are pretty great. This magnificent specimen is a Kauri pine, located outside the Cobb & Co Museum in Toowoomba. It was sadly too large to hug properly, but we gave it a nice bark-rub.

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Myth Busting Monday: Cars and Lightning

A giant Van der Graaff generator at the Boston Museum of Science creates lightning bolts, zapping a cage containing the show's presenter

It’s Myth Busting Monday again! Let’s zap this one once and for all…

Myth: Your car’s tyres will insulate and protect you in the event of a lightning strike.

Truth: Choosing to stay inside your car during a thunderstorm is usually the safest option – this much is true. But the protection the car offers has little to do with the tyres. In fact, it’s the car’s metal body that protects you!

“Huh? But metal conducts electricity…?”

Yep! The car’s protection comes from the fact that it is a hollow ‘cage’ made from an excellent conductor of electricity. Lightning is basically a stream of charged particles looking for the shortest path between a storm cloud and the ground. If its path happens to go via you, this is bad news. It’s generally not advisable to be outside in a thunderstorm, and especially not near something tall like a tree that is likely to attract the lightning (and send it via you).

But if lightning hits the top of a car, it will continue to travel through the metal body of the car AND the tyres (and safely around you) to the ground. This phenomenon was harnessed by Michael Faraday, who discovered that a continuous shield of conductive material would stop an electromagnetic field (including lightning and radio waves). He developed the Faraday cage in 1836 to protect electronic equipment from damage and interference.

Incredibly, a person inside a Faraday cage can even touch the metal on the inside of the cage while lightning is striking, and remain unharmed (NB. DO NOT TRY THIS PLS). This is demonstrated in one of the best science shows we’ve ever seen, at the Museum of Science in Boston, MA, back in 2012. The presenter stands inside the cage, nonchalantly running their hands around the metal bars, while the world’s largest Van der Graaff generator zaps the top of the cage with approx. 15 gazillion volts. 10/10 would recommend.

For more on this topic, check out Richard Hammond putting this theory to the electrifying test on Top Gear:

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