The duration of the spell says permanent see text
I am not sure hiw I would rule this as a GM but my question is. Does the spell end when you tranform the animal back into its normal form or could you change it back and forth indefinitely as long as the spell isn't dispelled.
Or is is one Transformation per cast.
I can see in a game where players are suitably high level and a 2nd level slot is negligible just allowing one cast to last forever but I don't know if that is the RAI.
I am normally the GM and could make my own call but I am playing the same druid in 2 games with a Shark Companion and being able to bring it around while on land and poping it out when we encounter water will be useful.
they are permanently carried until the spell is dispelled and they are an animal again.
(i.e. one transformation per cast)
(better solution is to get armor with the Hosteling property.