The Parent Whale and Child Whale are a pair of guest characters in Kirby: Right Back at Ya!
When a baby whale appeared in Dream Land's harbor, everyone was amazed and thought it was a whale parent searching for its missing child. King Dedede of course capitalized on this, making a boat to go whale watching. And of course it eventually turned out that the boat was a whaling ship in disguise, meaning that he really wanted to go whaling!
When the boat is swallowed by the whale, everyone finds that the whale's stomach is full of trash that people have been dumping in the bay. They help clean it out, but of course Dedede takes the chance to cause trouble by turning the whale into his own personal submarine. His plan is eventually ruined, however, when one of the missiles he fires from the submarine at Kirby and Kine hit instead what appeared to be an island, but turned out to be the back of an even bigger whale. That whale was the real parent whale who was looking for her baby - the whale from earlier was in fact her baby. The whales then attack and fling Dedede and Escargoon into the sky, and then happily swim off into the distance together, thanks to the help of Kirby and his friends in reuniting them.
The child whale is a huge black sperm whale calf with green eyes and is 2-D while its parent is much larger with a gray body and darker, narrower eyes, as well as eyelashes. She also wears an island on her back at first. Other than that, there's not really much else to say about their physical appearances.