Mauve-Mouth Ascidian

Herdmania grandis

Herdmania grandis is a species of sea-squirt that can be identified by its distinctive appearance. It typically reaches a maximum length of 16 cm and is characterized by its mauve-colored mouth. This species is found in the Indo-West Pacific region, particularly around Papua New Guinea and Australia. It inhabits shallow waters, primarily in environments such as lagoons and rocky reefs, where it can be observed at depths generally shallower than 40 meters, with most occurrences recorded at depths under 20 meters. As a sessile organism, Herdmania grandis attaches itself to substrates in its environment. It is hermaphroditic, meaning it possesses both male and female reproductive organs. This species typically reproduces through both cross- and self-fertilization, with eggs developing into lecithotrophic larvae before metamorphosing into benthic adults. Encountering this sea-squirt during a dive can be intriguing, as divers may find it clustered on surfaces, contributing to the biodiversity of the underwater ecosystem. The conservation status of Herdmania grandis has not been evaluated by the IUCN, and it is generally considered harmless to humans. Divers may enjoy observing this species as it plays a role in the marine food web, filtering plankton and organic matter from the water column.