Research indicates that size is significant, particularly for female sea snails from West Australia.
Up until recently, all of the Thais orbita marine snails, located off the coast of Perth, were affected by imposex, a condition linked to the anti-fouling agent TBT, which disrupts hormones and results in the development of a second sexual organ.
Although TBT was utilized on vessels in Western Australia until 1991, researchers at Curtin University discovered that a majority of females were developing penises on their foreheads.
TBT can persist in marine sediment for many years.
According to Monique Gagnon from Curtin University, imposex poses a threat to the survival of the snails.
“Typically, the male has its penis on the forehead, but in females, it’s an abnormal condition,” she explained.
“When that organ is located within the shell, it obstructs the release of eggs, rendering the female sterile. In severe cases, lack of reproduction can lead to death, as the egg bag can rupture and result in infection.”
Thais orbita primarily feeds on small worms, vertebrates, and decomposing animals due to its carnivorous nature.
Gagnon noted that these snails play an important role in promoting biodiversity since their predation on marine life allows space for other species to inhabit the area.
“If this snail were to completely vanish, we would lose its role as a predator, which could lead to decreased biodiversity.”
However, she mentioned that there is positive news for the snails: the proportion of individuals affected by imposex is decreasing, along with the condition’s severity, particularly the size of the penis on the forehead, which has been diminishing in each new survey conducted.
