Baby Sea Ponies
Well, hot on the tails of the Adult Sea Ponies were, logically, their baby counterparts. There were four sets in all, suggesting them to be more popular a venture than the grown ups. Instead of weighted tails, these little characters each came with a float or rubber ring in the style of a water creature to help them balance in the water. Again intended for bath play, each had the hole behind an ear that the adults also had, to help with balance. (Presumably Hasbro did not think about the problems of ponies getting full of water - internal mould is not uncommon with these guys!)
The original six baby sea ponies came in one of two poses and with one of three different styles of float. Each did feature in the UK comics, though their appearances were few and far between and often involved special magic to allow them to come ashore - or earthbound ponies to swim in the sea. They probably went on sale in the UK in the autumn of 1985, but were definitely well out on shelves by the Spring of 1986.
Their personalities even spread to promotional/sales catalogues: Argos introduced Backstroke as a "keen swimmer" and Sea Star as loving sandcastles!
Baby Sea Ponies
(Argos Catalogue, Spring/Summer 1986)
Like the Adult Sea Ponies, Baby Sea Ponies were friendly with Miranda the mermaid and also King Neptune who was, I think, Miranda's father, and who always gave an eye to the baby sea ponies when they so needed it.
Picture is taken from the UK insert. It seemed easier than using photographs for this section...;)