I recently spent a glorious sunny day on Willows Beach in Victoria. Staghorn sculpins (Leptocottus armatus) and many small soles raced to deeper water as we walked along in ankle-deep water. The tide was out. People were everywhere, but no one was lifting rocks to see everything hiding in plain sight.

Further up the beach was a line of marine macroalgae (especially Ulva, sea lettuce) stranded by the receding tide. Under each rock you can expect a handful of isopods, as well as shore crabs and small Dungeness crabs that scuttle away, and even the tiniest puddles under a rock sheltered up to 8 fish—sculpins and gunnels. The sun heated the beach, but under the algae-draped rock, water stayed shaded and cool and kept everything alive until the tide returned.

Most pools had tidepool sculpins (Oligocottus maculosus), and most were the typical grey-brown mottled form. But there also were many of these green sculpins—the same species as the typical grey-brown tidepool sculpin. These green sculpins are perfectly camouflaged in patches of sea lettuce.

A bright-green tidepool sculpin sure stands out from its typical grey-brown relatives.

Without the usual coloration to rely on, you have to look more carefully to see whether this is a tidepool or fluffy sculpin (O. snyderi). Fluffy sculpins have cirri (little wispy flaps of skin) along the lateral line in clusters of three to six, and the clusters of cirri follow the lateral line along the flank of the body. This photo—even though it was taken with my old iPhone 6. which performs poorly when taking macro shots—shows that the cirri along the lateral line are only found near the head, and they are single. This clearly is not a fluffy sculpin.

Next time you are on the beach and the tide is out, take some time to explore tidepools and rocky ledges along the shore, and carefully lift some rocks. You probably will find a lime-green sculpin or two. You may also find lime-green penpoint gunnels (Apodichthys flavidus) or rosylip sculpin (Ascelichthys rhodorus). If you are really lucky, you will find sculpins with bright-pink colouration to match coraline algae, or a blue-and-red-banded longfin sculpin (Jordania zonope). Even in this city, there is plenty to see along shore.