It has taken almost two years to plan, including building a special temperature-controlled crate for him, and co-ordinating complex paperwork across two countries.
Rhossi normally lives in the sea, but has to travel out of the water – first by helicopter from Anglesey to London, then by cargo flight to Houston, Texas, USA.
It means the journey needs to be completed as quickly as possible, and staff have to be constantly on hand to make sure he does not dry out or dehydrate.
Davidson said: “We have to make sure that the shell is really well lubricated, so we spread Vaseline all over to stop it drying out and flaking off.
“The same for the skin – it’s really delicate – and especially the eyes, which both have to be lubricated before he goes into the crate and again just before takeoff, or he will start to peel like someone getting sunburned.
“But I have had to go to the checkout in a chemist’s with about eight tubes of KY Jelly and three tubs of Vaseline and explain what’s happening when I get strange looks.”