Keyword Album: Hexabranchus sanguineusThis species of very large%2C strong-swimming nudibranch is one of the largest of all nudibranchs%3A specimens of well over 40 cm in length have been reported.The species name%2C sanguineus%2C refers to its bright red coloration%2C but a yellow variant also exists. This nudibranch has two very different modes of locomotion%3A crawling and swimming. When it crawls%2C the wide edges of the mantle %28the parapodia%29 are rolled up close to the body. When the animal swims however%2C the red parapodia unfurl%2C and are whirled through the water in a spectacular undulating motion%2C propelling the animal forwards. The animal was given the common name