To solve this problem, we need to identify which animal among the given options does not undergo metamorphosis. Let's analyze each option:$\newline \bullet$Moth:$\newline$ - Moths undergo complete metamorphosis, which includes stages such as egg, larva (caterpillar), pupa, and adult.$\newline \bullet$Tunicate:$\newline$ - Tunicates, also known as sea squirts, undergo metamorphosis. They have a free-swimming larval stage that transforms into a sessile adult.$\newline \bullet$Earthworm:$\newline$ - Earthworms do not undergo metamorphosis. They develop directly from eggs into juvenile worms and then into adults without distinct larval stages.$\newline \bullet$Starfish:$\newline$ - Starfish undergo metamorphosis. They have a larval stage that undergoes significant transformation to become an adult starfish.$\newline$Based on the analysis, the animal that does not undergo metamorphosis is the Earthworm.$\newline$Therefore, the correct option is Option 3: Earthworm.