Why does the Pobble lose his …

In the beginning, the poet  introduces us to  a young Pobble who is very proud of  his  toes His aunt Jobiska warns him that, pobbles often lose their toes by the time they mature. She tells him that his toes have a chance of salvation if he keeps his nose warm. The Pobble  henceforth wears a red flannel scarf on his huge nose. He decided to go for a swim one day, his scarf is stolen by a dolphin before he swims to the opposite shore. When he gets out of the water, he discovers his toes have vanished. As the Pobble mourns his lost toes, he is flabbergasted and contemplates on which creature of the deep may have taken them: A crawfish? A shrimp? A mermaid

It's a story about ; properly taking care of one's things, learning to let go of things that are really not all that important, being obsessed with material things,  accepting one's body image, about growing up and becoming an adult,  the inevitable things that may happen, fear of loss.