What I am curious about is why Terry named Him Io.
As I said -
Io is one of the Jovian Moons and said to be one of the most volcanically active places in the known solar system. Huge volcanoes have been witnessed on its surface and it's reckoned that it is so active it effectively turns itself inside-out.
But
Io was also a nymph, who was turned into a cow after being seduced by Zeus.
I have a feeling Terry is hiding a joke in there somewhere - but I can't imagine what.