#pleuronectodae

Have you ever see a flatfish and wondered “Huh, is that a rock sole (Lepidopsetta bilineata)?” Well, you’ve come to the right place! Here are two simple tips to answering the age-old question: rock sole or not rock sole?

Tip 1: L. bilineata is a unique species in that they do not bury themselves. Rather, they lay atop the sea floor. If you see a wild flatfish not in the water column or not as a pair of lil eyes sticking out of the substrate, there’s a good chance it’s a rock sole!

Tip 2: Now, Tip 1 alone is not enough. Even if the rock sole does not instinctually bury itself as a predation and defense mechanism, all flatfish may crawl on the substrate for short-range locomotion. Because of the chromatophores possessed by the pleuronectodae family, color cannot be relied upon, either. So what can you use to identify a rock sole? Well, gaze into their special eyes! Most flatfish in the north Pacific feature oblong pupils, but the rock sole has a bean shaped pupil! Illustrations below.

(standard flatfish pupil)

(rock sole pupil)