A hermit crab who has outgrown his old shell moves into a new one, which he decorates and enhances with the various sea creatures he meets in his travels.

A girl helps a crab with plastic wound around its claw while she is cleaning up a beach, and ends up inspiring others to take care of the beach as well.

"Best friends Peanut Butter and Jellyfish are constantly being taunted by their neighbor, Crabby, until they help him out of a jam"--

"Carina Felina is an arrogant cat with an appetite so huge that she eats everything and everyone who crosses her path as she ambles through Havana--until a small crab outsmarts her and saves the day."--

Little Crab, who lives in a rock pool on the seashore with Very Big Crab, is excited about going into the water until realizing that the waves are big and the sea is bigger, but Very Big Crab is there to offer reassurance.

When Crabby gets sick, Plankton is determined to play doctor and take care of his friend, even if Crabby does not want the help--until Crabby realizes that he can get Plankton to do all of his household chores.

Edgar the shark is getting the house ready for a visit from Santa Shark, and although he's skeptical, his friend Lotta the crab pitches in to help--but Edgar's worried about the lack of snow under the sea. Meanwhile, he's busy sending out Christmas "cods" and hanging a "reef" on his door.

Absorbed in his search for food, a shy hermit crab, disguised in a fancy new shell, inadvertently rescues a flounder caught beneath a trap and wins the admiration of the other marine animals.