Why do barnacles ride whales?

Barnacles don't "ride" whales in the sense of choosing to do so. They are filter-feeding crustaceans that attach themselves to surfaces for their entire adult lives. Whales are simply large, mobile surfaces that they can attach to.

Here's a breakdown of why barnacles end up on whales:

* Larval stage: Barnacle larvae are free-swimming and must find a suitable surface to attach to.

* Attachment: When they find a suitable surface, they secrete a sticky substance that firmly glues them in place.

* Whales as hosts: Whales provide a stable, large surface, often with currents that bring food to the barnacles.

* Benefits: Barnacles benefit from the constant movement of the whales, which allows them to access food and avoid being settled in one location.

So, it's not a case of barnacles "choosing" to ride whales, but rather a consequence of their unique life cycle and the opportunities provided by whale bodies.