Photo of the Week: October 26, 2009

Hi Gang!

It's been a few weeks since I shared a shark photograph, and that is about as long as I can go without! That's what happens when you fall in love with sharks. So for this week's POTW I have selected an image of a lemon shark that is resting on the sandy bottom at Tiger Beach in the Bahamas.

Tiger Beach has been named because it is such a great place to go to find and film tiger sharks, but there are far more lemon sharks than tiger sharks there on a typical day. In fact, I once counted 47 lemon sharks and 3 tiger sharks while I was standing on the swim step getting ready to make a dive. The disparity between lemons and tigers is not always that great, but on an average day I do expect to see more lemon sharks than tiger sharks.

The obvious kicker in the photograph that accompanies this piece is that the shark is accompanied by a remora that has decided to attach itself to the shark by entering the shark’s mouth. That’s an interesting choice for a resting place to say the least, especially considering the fact that lemon sharks commonly prey upon a variety of fishes. However, once I thought about why the remora might select such a resting place the site made more sense.

Like many species of sharks, lemon sharks generally stay on the move. Most sharks need to swim in order to respire. However, some species are capable of periods of rest during which they are able to move sufficient amounts of oxygen-rich water across their gills so that the sharks do not suffer any injury. Lemon sharks are such a species.

Lemon sharks are often accompanied by one or more remoras, and I have photographed lemon sharks that were accompanied by more than a dozen remoras. The remoras appear to prefer to attach to or accompany sharks that are on the move. If the shark is not swimming, then the remoras seem to prefer to find a place where the water around the remora is moving. My guess is that the remora in the lemon shark’s mouth prefers to be there instead of elsewhere on the shark’s body because there is some water movement through the shark’s mouth. Admittedly, that is just a guess, but it makes sense to me.

The shark appeared to be irritated with the remora’s chosen resting site, and I saw and heard the shark forcefully snap its powerful jaws closed on three occasions. Each time the remora was able to move fast enough to avoid becoming lunch. And each time the remora swam right back into the shark’s mouth. There is some thinking that considering its resting place no other creature is likely to bother- meaning try to eat- the remora. This means that as long as the remora keeps a sharp eye out for this lemon shark, and is quick enough to avoid getting caught, the remora actually benefits from such a seemingly risky resting place because it doesn’t have to be concerned about any other potential predators.

I took this POTW image with a Nikon 17 to 55 mm zoom lens set at 40 mm. The lens-to-shark’s mouth distance was approximately four feet. That was about as close as I could get without causing the shark to get up and swim away. I used the shutter-priority shooting mode and noted the f/stop that was determined via my light meter reading. I slightly under powered my strobes accordingly because I was in such shallow water (roughly 18 feet) that I didn’t need much artificial light, and I was afraid of over exposing the sand and the more lightly hued body parts on both the shark and the remora.

I did my best to move very slowly to avoid spooking the shark while setting up my shot and when taking the picture.

I hope you enjoy this week's POTW, and I look forward to seeing you next week!

Marty