Earthworms form herds and make “group decisions”, scientists have discovered.
The earthworms use touch to communicate and influence each other’s behaviour, according to research published in the journal Ethology.
By doing so the worms collectively decide to travel in the same direction as part of a single herd.
The striking behaviour, found in the earthworm Eisenia fetida, is the first time that any type of worm, or annelid, has been shown to form active herds. …
In two-thirds of these trials, the worms followed each other.
“I have observed contact between two earthworms. Sometimes they just cross their bodies and sometimes they maximise contact. Out of soil, earthworms can form balls,” says Ms Zirbes.
A modelling study then showed that, by using touch alone, up to 40 earthworms could follow each other in a similar way, explaining how herds of the animals preferred to move together into one chamber in the initial experiments.
“To our knowledge this is the first example of collective orientation in animals based on contact between followers,” the researchers wrote in the journal.
“It is also the first one of collective movements of annelids.” …