Giddy-up little fish! The Secrets of the Saddle Wrasse

Lydia Weltmann

Coral reefs are well known for their biodiversity. The colorful ridges house dozens of species of fish, mollusks, sponges and more, all thriving in the ecosystem the reefs are a part of. Some, like the Saddle Wrasse, merely use coral as a home, taking advantage of the biodiversity. They don’t eat the reefs, merely the other marine creatures that live around it.

A Saddle what now?

A Saddle Wrasse is a small fish endemic to the coral reefs of Hawaii. It is one of 43 different species of wrasse; all of saddle wrasse 2them share the same elongated body that tapers at the head and the tail, but the Saddle Wrasse stands out because of its coloration. An adult has a blue head and a broad orange stripe just behind that, looking very much like a saddle. The rest of their bodies are green with lavender highlights. This coloration however is just for adults. Juvenile saddle wrasses have a greenish back, a pale belly, and a black stripe stretching from their nose to their tail.juvenile saddle wrasse2

These fish don’t grow very big, the largest reaching only about eleven inches length-wise. Despite that, they are one of the most populous fish in the coral reefs of Hawaii. Their small size is actually advantageous, allowing them to dart through the coral to hunt their favorite meals. Saddle wrasses spend their days stalking reefs for tasty crustaceans, mollusks, and urchins. Then, at night, the little fish sleep in the crevices of the reefs or burrow in the sand.

You’d think with all these wrasse hanging around the reefs, they’d hunt in groups and be buddy-buddy with each other. They actually don’t really like one another for the most part. Wrasse prefer to be alone or only with a small group of other fish. The population largely consists of females, so any groups they do form into tend to have only one male, the rest of the school being female. Wrasses also tend to get more aggressive the older they get, so maybe it’s better they avoid each other anyway…

It’s a bird! It’s a plane! It’s a….fish?

Saddle Wrasse also stand out from other fish in a few other neat ways. They are easily spotted not only because of their coloration but because of the way they flip their pectoral fins. Instead of sweeping side to side like most other fish, wrasse flap their fins up and down, like a bird. They are one of the most common reef fish in Hawaii, so perhaps swimming like a bird is some secret advantage?

Another little fact about these fish is that most of them are actually born female. They don’t all stay that way though. Many of them, as they transition from juveniles to adults, have a sex change and become what’s called ‘terminal phase’ males. These males become dominant territory holders and maintain a harem of females in that territory. Terminal phase males have a white stripe behind their orange saddle stripe, making it easy to tell which of these wrasse have undergone a sex change. terminal phase male saddle wrasse

They may not be as brightly colored as the coral reefs they live in, but Saddle wrasse are certainly an interesting part of the reef ecosystem. And, with their flapping fins and bright orange stripes, they aren’t too hard to distinguish from other fish. Assuming, that is, you can even find them flying through the coral after their prey.

 

Sources:

http://animal-world.com/encyclo/marine/wrasses/SaddleWrasse.php

http://www.waikikiaquarium.org/experience/animal-guide/fishes/wrasses/saddle-wrasse/