Thorunna halourga

Thorunna halourga is a species of sea slug characterized by its pale lilac mantle that transitions to purple near the rhinophores and gills. The mantle margin features a broad white band and is slightly undulate. The rhinophores have a purple stalk with orange-edged lamellae, while the gills are white with orange axes. This species can be found in tropical waters, having been recorded in regions such as Papua New Guinea, the Philippines, and tropical eastern Australia. Typically inhabiting benthic environments, Thorunna halourga is often found at depths shallower than 40 meters, with most occurrences recorded at depths around 30 meters or less. It thrives in various habitats including coral reefs and rocky reefs. As a simultaneous hermaphrodite, this nudibranch engages in a unique mating behavior where individuals exchange roles as male and female during reproduction, leading to the deposition of eggs on the substrate. Encounters with Thorunna halourga during dives can be intriguing, as divers may observe its distinctive coloration and behavior. While the conservation status of this species has not been evaluated by the IUCN, it has been reported from multiple dive sites, indicating a presence in popular diving regions.