Ceti eel

The Ceti eel is the only surviving indigenous animal to the planet Ceti Alpha V, similar to arthropods found on Earth. It is a robust creature, able to survive extreme ecological conditions. It has multiple legs, a large set of mandible claws, and body armor-like skin. Adults can grow up to 18 inches long and incubate their larvae inside their mouths. The eels appear to be partially blind, as they spend most of their lives underground burrowing.

Ceti eels are dangerous to humaniods as the larvae have a preference of infesting warm orfices, particularly the ear. Once inside, they anchor to the victim's cerebral cortex. This causes extreme pain and makes them subjectable to outside suggestions. Once the larvae matures, its host slowly goes mad and eventually dies.

In 2285, the USS Reliant came to Ceti Alpha V, mistaking it for Ceti Alpha VI. Khan Noonien Singh used ceti eels to control Capt. Clarke Terrell and Com. Pavel Chekov after they beamed down to see if the planet was suitable for use in the Genesis Project. (STII: The Wrath of Khan)

Most species consider the animals a biological hazard and will quarantine them if encountered. They are illegal to own, transport, or sell within the confines of Federation space. It is rumored, however, that the Cardassian Obsidian Order used to include the eels in their interrogation sessions.