On a collision course with critters in the sea

by B. N. Sullivan

This post was inspired by a comment on our Rush Hour On the Reef photo in which Chris asked, "It's probably a fairly silly question, but do you ever get run into by fish?" The short answer is, "No, not really." But we have had some very close calls.

Little fish, like the fast-swimming Fuslier Fish we showed you recently, often approach in a large school, and at a high rate of speed, but they manage to steer en masse around obstacles -- including divers -- by making high-speed turns in unison, or simply by splitting the school for a moment, with half the fish passing on each side of the diver. Once past the obstacle, the fish reunite into one school again and continue on their way.

Other kinds of small fish that form dense schools do more hovering than swimming around. Sometimes a diver will encounter a dense school of Sweepers or Glassfish hovering in an underwater canyon, or even inside a shipwreck or a cavelet. As the diver (or a large fish) swims toward the apparent wall of little silvery fish, they may scatter. More often, though, the school simply parts like two halves of a stage curtain to allow the bigger swimmer to pass through, then closes again afterward. It can be an amazing sight, and an almost dream-like experience.

In sum, smaller fish usually get out of the way of larger fish and divers, one way or another. Now let's talk about larger fish -- much larger fish.

Over the years, we have noted that the larger the animal, the more likely it will notice divers and even come close to have a look. On occasion they come very, very close.

Consider the photo at right: that's a Whitetip Reef Shark (Triaenodon obesus). I first saw this particular shark while it was about 75 feet (23 meters) in front of me. It was coming toward me at a leisurely pace, so I settled into position and aimed my camera, hoping it would come close enough for a good photo.

Through the viewfinder I watched it come closer and closer, heading straight at me now. It had spotted me, for sure.

About two seconds before I snapped the shutter for this shot I thought I might have to duck out of the way, because the shark had now picked up speed a bit and I feared it might bump into me, head on. I knew it had seen me, so it was starting to feel like a game of chicken! Then at the last moment, the shark made a sharp right turn directly in front of me and swam off (as if that had always been what it had intended to do!), avoiding a collision.

This was neither the first nor the last time that one of the larger species on the reef had intentionally come right up to one or both of us to look us over, and made a very close pass. In fact, sharks and barracudas often do this. So do large groupers, wrasses, jacks, and every kind of marine mammal we've ever been with in the water, including dolphins and whales. (Long-time readers of The Right Blue will recall our tale of close encounters with humpback whales.) But none of these cases ended in a collision, either.

On the other hand, we've had, or witnessed, quite a number of very close calls -- near-collisions with big critters in the sea. Usually this happens when two critters, or rather a critter and a diver, round a corner or swim over a rise at the same time from opposite directions, unaware that the other is approaching until they nearly collide.

Another scenario for close scrapes occurs when a diver inadvertently startles an animal, and the animal reflexively attempts to escape the scene. Once, while diving with a good friend and a visiting diver, we took the visitor to a place where we knew Whitetip Reef Sharks went to rest. The spot was a sheltered cavelet in the face of an underwater cliff. We approached carefully from below the cavelet and quietly positioned ourselves so that we could peek inside. My friend shined his light onto the ceiling of the cavelet, so that the light reflected down just enough for us to see two sharks 'sleeping' inside. The visitor, wanting to get a better look, shined his light straight into the cave, right into the face of one of the sharks. The shark startled and shot out of the cavelet like a missile, grazing my friend's head on the way, and knocking off his dive mask in the process.

On another occasion, Jerry and I passed below a ledge where drowsy sharks sometimes lolled. I was in the lead, with Jerry following just a meter or two behind me. As best as we can reconstruct what happened, we think my exhaled air bubbles must have passed by a shark on that ledge and disturbed it. It was another 'missile launch' situation, but this time the shark swam between Jerry and me, and as it did, it passed right in front of Jerry's face. Reflexively, Jerry's arms shot forward and he shoved the shark. This shocked the poor shark even more, and it sort of jack-knifed sideways. By this time I had turned around, and now the shark went berserk, probably thinking we were trying to corral it. It swam around frantically in a very tight circle for two or three revolutions (like a puppy chasing its tail) before it saw its opening and catapulted itself from between us and went careening down the reef. We stared after it until we could no longer see it, our hearts pounding from the unexpected excitement on an otherwise tranquil and leisurely dive.

Here's one more photo from a near-collision we had with a large stingray. From a technical point of view, it's a lousy shot, but I'm posting it anyway because it has such an interesting story.

We were on a deep sandslope, where I was shooting macro photos of small creatures that inhabited the nooks and crannies of a large, irregular rock. We were both crouched over the rock, engrossed in the task. Jerry looked up briefly, just in time to see an Amberjack swimming up the slope, heading right toward us. Jerry nudged me and pointed toward the Amberjack. I turned my head to look, and noticed that there was another, darker creature moving along the sand, beneath the Amberjack. In one of those 'lightbulb' moments of comprehension, we instantly recognized that we were witnessing a rare sight: a large deep-dwelling stingray species hardly ever seen by divers. Even though my camera was set up for macro, I whirled around and snapped this one shot, just as the Amberjack veered away, and the stingray sort of skidded to a stop, touching me, but just barely.

What looks like snow in the photo is light from my camera's strobe, reflected on sand particles that the stingray and I had stirred up at that moment. An instant later the big stingray did an urgent about face, stirring up a huge cloud of sand particles as it quickly retreated back to the depths.

In case you are wondering about the stingray, it looked to be about 1 to 1.5 meters across. It is either a Hawaiian Stingray (Dasyatis brevis) or a Brown Stingray (Dasyatis latus), but the photo is not clear enough to determine which it is with certainty. Both are known to inhabit deep sandy areas in Hawaii. They are uncommon around reefs, so they are rarely seen by divers. This was one of only three or four encounters we have had with one of these stingrays in all our years of diving in Hawaii, and this was the only time I got to photograph one.