Tryon's hypselodoris

Hypselodoris tryoni has a brown body and white foot. The body and upper dorsum are covered in purple spots ringed with white or light-brown. The gills are typically translucent white or light-brown and the rhinophores are brown to dark-brown and covered in circular white lines. It has a thin blue or purple line on the mantle edge. There is some colour variation between individuals. Hypselodoris tryoni is similar in appearance to Goniobranchus geminus, Goniobranchus kuniei and Goniobranchus leopardus, although it lacks the wide purple mantle edge line present in those species. Goniobranchus species also tend to have a lower, more rounded body. Sea slugs such as Hypselodoris tryoni, are known to exhibit trailing behaviour where up to four animals will follow one another very closely, often touching. It is not known what causes this behaviour. Hypselodoris tryoni reaches at least 60 mm in length and has been observed to raise and lower its head while crawling.