The Selm were a race native to Hodunk, a planet within the Federation. The Selm were an intelligent ocean-dwelling cetacean race who bore a slight resemblance to Terran porpoises. Like them, they were playful and friendly. They possessed an advanced civilization despite not having created a single artifact. Their language was equally advanced and highly complex, relying on a wide range of sounds transmitted through water. By the late 23rd century, universal translators did not allow for conversation with the Selm beyond that of crude pidgin.