Low Tide in the Surf Zone
Surfperch live on sandy beaches which can be vast, uniformly colored and featureless. It’s a drab place. Sometimes the beaches are broken up by rock features but true sand-dwellers eschew the rocks. In the photo above, my pack is sitting where surfperch will be feeding in a few hours. Surf zone prey frequently camouflage themselves by matching the sand. Check out the gallery below to see some examples.
Surfperch are prey too. The silver surfperch, Hyperprosopon ellipticum, blends in to the sandy background a little differently than the prey shown above. Silver surfperch have silver skin, clear scales and counter-shading. Silvers are like little swimming mirrors. If you want to find out more about how silvery fishes blend in, check out hiding behind mirrors in Camouflage Under Water.
In previous posts, Choices, Choices…Everywhere and The Color of the Caudal, I have shown that surfperch use their fins to bring color into the drab surf zone. Even though they are prey and rely on camouflage to avoid predators like harbor seals, terns and larger fishes, they have found a way to show off. A small proportion of both male and female silver surfperch display splotches of color on the anal fin. Check out the photos below for some examples.
I have even seen a boldly colored anal fin flag half orange and half black. Colored splotches are rare, however. Last year I recorded several categories of anal fin color on 23 female and 36 male silver surfperch. In the table below you can see that the most common colors are clear and gray wash and you can see just how rare it is to find bold colors on the anal fin.
| clear | gray wash | gray wash/orange spot | orange spot | orange flag | black spot | black flag | tot | |
| female | 9 | 14 | 0 | 0 | 0 | 0 | 0 | 23 |
| male | 19 | 10 | 1 | 1 | 1 | 1 | 3 | 36 |
| tot | 28 | 24 | 1 | 1 | 1 | 1 | 3 | 59 |
In contrast, when redtail surfperch, Amphistichus rhodoterus, show off they rely on red fins all around. It’s easy to see why another common name for redtail surfperch is pinkfin.
Male redtail surfperch
I’ve observed hundreds of redtails and only seen a couple of color splotches on the anal fin. The photo below shows one of those rare occurrences.
Male redtail surfperch
There are probably tradeoffs involved in adding a color spot on the anal fin. Orange and black badges surely reduce camouflage, so there must be some special advantage. If there wasn’t, we wouldn’t see them at all. I’ve discussed orange badges a little in a previous post, An Abundance of Orange. The anal fin is not the only fin on fire we see in theoutershores’ surfperch. The caudal and pelvic fins have a story too.
