Nudibranchs of Hawaii Main Page
For the novice nudibranch detective, the Kangaroo Nudibranch is fairly easy to find during the day due to its striking colours, relatively large size (to 4″ or 100 mm) and stiff, elongate body. We have only found them in the North Kihei, Ma’alaea area but there they are quite common in water from 2 metres down to free diving depths. They come in a variety of spectacular colours from orange/yellow/maroon/brown/red to anything in between. All of them have a lilac/purple marginal trim (often broken) with creamy white blotches. The lilac/purple spots are spread about the mantle and tale and tip the rhinophores. They are a bit of a strange looking creature with a thick Kangaroo-like tale, a shoe-horn shaped flap over the gills (marking the end of its mantle) and branchial gills that are a striking, orange/yellow and white when viewed closely.
See Sea Slugs of Hawaii for more taxonomic details — and an interesting description of how their horn holds toxins that might prevent prey from devouring them entirely.