phoresis

Phoresis, or phoresy, is rooted in the Greek words phoras (bearing) and phor (thief). It is used to describe a non-permanent, commensalistic interaction in which one organism (a phoront or phoretic) attaches itself to another (the host) solely for the purpose of travel.

Phoresis – Wikipedia
https://en.wikipedia.org/wiki/Phoresis