Photo of the Week: June 28, 2010

Hi Gang!

Imagine yourself immersed in water that is so thick in jellyfish that they obscure your vision. Now let’s take things one step farther and imagine that you are not wearing a wetsuit or any other garment that provides thermal protection or a barrier against the potentially potent stings of jellyfishes. In most locations and with most species of jellyfishes the described scenario would be a diver’s nightmare, but that is anything but the case in Palau’s Jellyfish Lake on Eli Malk Island. In fact, Jellyfish Lake is the perfect place to take a swim with as many as 13 million golden jellyfish (Mastigas papua) along with the less commonly encountered moon jelly (Aurelia sp.), and that is exactly what the snorkeler pictured in this week’s POTW is doing.

It is not exactly true that golden jellyfish can’t sting as is believed by many divers. Golden jellyfish are described in the phylum Cnidaria, and like all cnidarians they are equipped with stinging cells. It’s just that in their case, the sting is especially weak and does not cause a reaction or pose a threat to most humans. That said, people that are especially sensitive to stings and that are prone to allergies should consider wearing a wetsuit or other form of protective clothing. Many people do report feeling a tingling sensation on their lips and other body parts with increased sensitivity.

Most jellyfishes depend on the stinging cells in their tentacles to fend off potential predators and to immobilize their prey. But golden jellyfish are an exception to this rule as they depend on the by-products of symbiotic algae that live in their tissues in order to acquire the majority of their food. The algae provide energy for themselves and for the jellyfish by converting sunlight into sugars in the process known as photosynthesis. The golden jellyfish share some of those sugars with their hosts. Golden jellyfish also capture some zooplankton by using the stinging cells in their tentacles. Because the jellyfish depend upon the sun they migrate across the lake each day in order to maximize the amount of sunlight they receive.

Jellyfish Lake is a marine lake, an isolated body of seawater surrounded by land. There are more than 50 marine lakes in the South Pacific paradise of the island nation of Palau, and at least five of these marine lakes are home to golden jellyfish.

This week’s POTW was created with a Tokina 10-17 mm lens. The use of such a wide angle lens helped me reveal the density of the jellyfish. I used a pair of strobes to add a little light to the diver’s face and to light the jellies, but I had to be careful not to grossly over expose the jellyfish in the foreground of my shot. I used my camera's aperture priority mode so that I would know my f/stop and be able to keep it constant. Knowing my f/stop I bracketed my exposures by varying my strobe power.

I hope you enjoy this week’s POTW, and that someday you can join Captain Steve on a trip to Palau.

See you next week!

Marty