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Wednesday, November 4, 2009

Sea Things #22: Yellowhead Jawfish

Sea Things is a regular feature on my blog where I profile a different sea creature. Look for it weekly, or something close to weekly.


For the month of November, Sea Things is going to be devoted to macro. That's right - all things small. One of the things that happens as you move from a newbie diver to a more experienced diver is that you start observing some of the smaller things on the reef. When you first start diving, it always seems like you're looking for the big guys - turtles, sharks, rays -- large things that are really exciting. However, there are many dives where you never see those things. Sometimes vis is bad, sometimes those big things are just not around. What then? Well, there are TONS and TONS of small, interesting things living all over the reef. They're often very common, and once you learn what to look for, they're easy to find. I love my magnifying glass, and I love looking at small things on a dive.

This week's macro fish is the Yellowhead Jawfish, or Opistognathus aurifrons. These little guys are a couple of inches long - about 3 or 4 inches, max. They live in sandy areas of the sea floor, and are mostly found in areas with a lot of coral rubble (kind of like rocks, old, dead coral that has broken off for whatever reason and gathers in one spot). They live in little burrows or holes that they dig themselves.

Their burrows actually quite intricate. To me, they look like just a hole, but in fact there is more to them than that. They dig out a hole six inches deep and eight inches wide, then create a brickwork above it using shells, bits of coral and rocks, to support a tunnel to the surface. At the bottom is a chamber lined with sand where the jawfish will sleep. They are very territorial and will not let anyone near their home except a mate. They spend a lot of the day finding rocks, coral and shells to keep up the tunnel and chamber, and are meticulous about it. It's very interesting to watch. At night, a bit of shell blocks the entrance to the tunnel so that the fish can get some shut eye.

Yellowhead Jawfish are found all over the Caribbean, and can be found from Florida to Argentina in the Atlantic. I have frequently seen them in Bonaire, Belize, Turks & Caicos, and the Cayman Islands. As I swim up to a rubble area, I'll often look for them. Their coloring really helps them up against sand, as sometimes they can be hard to spot. Usually, there are many of them in a single area. They will hover a few inches above their burrow, and sometimes when they're comfortable they'll swim maybe a maximum of 6 to 8 inches away from their burrow. When they're scared or startled, they'll immediately and fast, swim back to their borrow and enter tail first. If you are still and quiet and keep your bubbles small, they'll often be back out again in a few minutes, at least popping their little heads up out of the sand.

Sometimes, I'm underwater looking at these little guys and all I can think about is - these animals live right there on the sand, and won't go more than a few inches away from a single spot. That is their entire world, just that little area. Forget the fact that they don't know about the topside world, they don't even know about things going on with the reef 10 feet away from them. Kind of an interesting thought.

These jawfish feed on plankton and small, small things - I suppose whatever floats near them. One of the more interesting things about them is that the males take care of the eggs. They're called paternal mouthbrooders, which means that the male holds the eggs in his mouth until they're ready to hatch. Whenever I find a cluster of jawfish, I am hopeful that I'll find one with eggs in its mouth. To date, we have yet to find one, but I still look on many dives.

The diver hand signal for jawfish is to point at your jaw. They can be found from 10 to 160 feet, and I almost always find them in areas of white coral rubble.

Is there a creature that you would like to see featured in Sea Things? If so, shoot me an email and if I can, I'll write about it. Photos on this post are courtesy of Todd Krebs.

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