Meet the rock-mover wrasse, the fish that looks like seaweed

  • Terry Lilley / Contributed photo

    Juvenile Wrasse Rock mover

  • Terry Lilley / Contributed photo

    Baby Wrasse Rock mover

The rock-mover wrasse grows to be 12 inches long, but the babies look more like a piece of limu (seaweed) than a fish. The two-inch-long baby rock-movers have branching fins that grow out from their body, resembling the seaweed that grows on the reef.

The surf tears off some of the seaweed, and it collects in holes and valleys in the reef, and that is where you will find the baby rock-mover wrasse. The wrasse undulates and twists its body to look just like a piece of seaweed floating by. Often, when I point the fish out to divers, they do not even know what they are looking at.

When the rock-mover wrasse grows to about four inches long its fins become more rounded, like the normal fins on most fish. It then moves out of the seaweed and up onto the rocky reef where it flips over rocks with its strong jaws to find small animals under the rock that it feeds on. It is truly amazing to watch this fish feed as it lays sideways on the sea floor and bites a rock that is larger than itself. The fish then flips upwards and pushes off of the sea floor with its strong tail fin, flipping over the rock. This would be like us humans laying down on the street and biting the bumper of a car then jumping upwards flipping the car over. This behavior gives the fish its name: the rock-mover wrasse.

Many of the other fish on the reef love to follow the rock-mover around, as they will zoom in and try to steal the critters under the rock before the wrasse can grab them and have its hard-earned meal. In the sea you have two types of predators. One hunts its own prey and the other tries to steal the prey once it is found. It all seems to work in balance in the end.

As far as we know, the rock-mover wrasse does not have its own specific Hawaiian name, but many of the wrasse species are called “hinalea,” which refers to the goddess of the coral reef, women and the moon. Like most all wrasse species, the baby rock-mover wrasse are all hatched out as females, then some will convert into males for breeding when they become adults.

You can see the rock-mover wrasse on the underwater educational web page atunderwater2web.com, in my movie “The World;s Guide to Hawaiian Reef Fish,” and also follow my daily marine life Facebook post under my name. You can read more about this amazing fish species on our non profit web and Facebook page at www.reefguardians.org.

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Terry Lilley, a marine biologist, lives in Hanalei. His websites include underwater-2web.com and gofundme.com/5urrm4zw.

1 Comments
  1. randy kansas October 4, 2020 3:57 am Reply

    thanks Terry for the fun articles; refreshing, educational and gives us a break from all the crummy news !


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