"Memory of an elephant" is an English proverb that means really good memory. I was a bit curious about it so I looked it up on the Internet.

Turns out, it has scientifically been proven that elephants have really good memory. (Source) But, after reading about elephants, I started reading about spiders (I don't know why)

It's been an urban myth, I guess, that a spider's legs are immune to adhesion i.e. a spider's legs can walk on sticky surfaces (webs) But, after just a minute of reading, I understood that it's not the case. A spider isn't immune to adhesion. Spiders just have the option of making sticky web and normal web.

That means, the spider remembers which part of the web is non-sticky and treads only on that part.

Even in your house, if you see a cobweb, what do you do? You remove it and kill the spider if it's nearby. But if he's not, he will weave another web and he'll have to remember which parts of it are sticky.

And that's just a common spider. Bigger spiders that live in forests weaves HUGE networks of webs and they still know which part is safe to walk on.

According to the article on elephants, one elephant remembered another one for 23 years even though they were together only for a few weeks. It's safe to say that an elephant's memory span can go up to 30 years. And according to the same article, an elephant's lifespan is 50 - 60 years. Also, elephants can keep track of around 30 companions at once.

Now, a common garden spider lives for 1 - 2 years and will remember about his webs for all his life. Bigger spiders like tarantulas live for 25 years or so, and they will remember about their webs for all their life as well.

I really hate it that the proverb is "memory of an elephant", when it could've been a number of other animals. I just happened to read about spiders and find out that they have an excellent memory as well.