Hamish,
About 30 years ago I was going on a trip and I asked all of my kids what they wanted me to bring back for them. One of my teenage foster daughters asked for a tarantula. This young lady had gone through very traumatic events in her life. She dressed in leather with spikes and had one half of her head shaved and the other half dyed purple. If she "looked" tough people would leave her alone. 
I managed to catch a tarantula while in N.M. and bought a little cage to carry it in. I covered the cage with a cloth. On the first two legs of my return trip, I had no problem. I told security (before TSA) what it was and then showed them. 
But, in LA, I was "carried" out of the security area by two huge security guards. The airline told me NO FLIGHT with the spider. I got my dander up and ended being kicked off the flight. I finally found a sympathetic airline who suggested I put it in my backpack and let a different security crew know ahead of time. Made it home a day later with it 🕷.