Nightcrawlers have a built in anxiety syndrome called,Four Corner Syndrome.Scientist in Sweden discovered nightcrawlers are descendants of the Pactoriousnatturoucas,( night venturers ),they were known to travel to the 4 corners of the earth.Their restlessness led them to search for non boundary lands,often driving them deeper underground,or higher into the mountains.
When the Pactoriousnatturoucas went into the earth,where the temps became to warm for reproduction,they began to die in mass numbers.Those that survived made their way back toward the earths surface,and through millions of years of breeding,the instinct of survival climbing has become forever imbedded into their offspring.
Swedish scientist also discovered the Four Corner Syndrome can be reversed by placing younger/ breeding age crawlers in a cornerless container,after two generations the new crawlers will be neurologically imprinted to circular travel,thus eliminating the once instinct driven desire to climb........Hope this helps