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Ocean Watch
By Susan Scott
Monday, April 10, 2000
OVER the last month, several friends have told me that the numbers and types of fish inside the reef at Hanauma Bay are way down from the past. Rare species now
visible at HanaumaLast week, I went to see for myself and had the same experience. The keyholes (open spaces between the reef flats) were nothing like they once were. Due to the fish-feeding ban started in the bay a few months ago, those teeming, nipping schools of fish have left for greener pastures.
This was disappointing since it was those swirls of colorful fish in the bay that, years ago, steered me toward marine biology. I wanted to learn their names, what they ate and how they survived. Besides that, swimming in the midst of all those species was fun.
TODAY, the bay is still fun. You may have to look harder to find fish but when you do spot some, you might be pleasantly surprised.
I was.
When I swam over a seemingly barren stretch of sand, a rare razor wrasse suddenly appeared. These wrasses are hard to find because when threatened, they plow headfirst into the sand, then "swim" beneath it. This behavior makes for good hiding, but it is also useful in catching one of their favorite meals, garden eels.
To catch an eel, the razor wrasse sometimes dives directly into the eel's burrow and grabs it. Another tactic is to sneak beneath the sand to the side of a burrow, then snatch the eel when it peeks out.
If you get lucky enough to see one of these sand divers, you won't forget it. Razor wrasses bear striking brown and white bars on their bodies, accentuated with black spots. On their back, belly and head are frilly fins that remind me of lionfish.
Since I have only seen a few razor wrasses in my life, this was a thrilling sight. And brief. Before I could alert my swimming partners, the fish lunged into the sand and disappeared.
The bay's "empty space" sheltered other fish I had not before seen inside the reef. A moray eel, its body as big around as my calf, was wound like a pretzel into a small, freestanding rock formation. We could see the eel's body from several sides of the rock but never saw its head. White spots dotted the robust brown body.
THE ability to make tight curves in their bodies serves morays for more than just shelter. When a moray catches a fish too big to swallow whole, many species employ a behavior called knotting.
With its tail, the eel makes two simple knots in its long body. Then, with the too-large prey clenched firmly in its teeth, the moray backs its head through the knots. When the fish gets stuck in the tight space, the moray can then rip off a mouthful of flesh. Other times, when the captured fish gets to the moray's knot, the moray will tighten it, breaking the fish's bones and squashing it flat. The meal is then small enough to swallow.
The twisted eel I saw was probably a whitemouth moray, although without seeing the inside of its mouth, it's hard to say for sure. Distinguishing morays can be hard since members of even the same species often display wide color variations.
Some fish, such as one called a comet, count on mistaken identity. Comets are a grouperlike species from Indonesia (not found in Hawaii) that mimic whitemouth morays. This chocolate brown, white-spotted fish has a narrow body and long, continuous fins. By looking like eels, comets may be safe from potential predators who don't want to mess with a moray.
No, the fish don't swarm at Hanauma Bay like they used to. But their absence has cleared the way to see new ones.
Marine science writer Susan Scott's Ocean Watch column
appears Mondays in the Star-Bulletin. Contact her at honu@aloha.net.
