Photo of the Week: November 14, 2011

Hi Gang!

Let’s go back to Maui for this week’s POTW. It’s a profile photograph of the face of a giant frogfish, Antennarius commerson, that I captured on a dive with Captain Steve on the backside of the island of Lanai. The species is also commonly referred to as Commerson’s frogfish.

Frogfishes are often referred to as anglerfishes by fishermen in reference to the lure-like appendage connected to the first ray of their dorsal fin that is used to attract unsuspecting prey to within striking range. Worldwide there are approximately 300 species of anglerfishes. %0 of these species are known as some type of frogfish. The family Antennariidae contains the most species of frogfishes.

On the whole, frogfishes are a rare find, but they appreciated by any observant diver who comes across them. Masters of camouflage, frogfishes adapt to look almost exactly like the surrounding environment, and as a result are extremely difficult to spot when resting. At rest a frogfish often looks like a sponge, branches of corals or large clumps of encrusting algae, and some species actually cultivate bits of algae that grow on their bodies to help them in the art of camouflage. Their color ranges from off white to vivid hues of oranges, yellows, reds and greens. Some fish are solid, others mottled and others spotted depending upon the look of their surroundings and their “mood of the moment.” Their globular, somewhat humorous looking bodies are highlighted their small and upturned mouths giving these fish a face that “only their mother could love.”

While finding a Frogfish for the first time is certainly challenging, many specimens can often be found for days, or even months, on end as they remain in almost the exact same spot in the exact same position. And if they are not there as expected, often they can be relocated within a few inches or a few feet of their original location. Once a frogfish seems certain that it has been discovered they tend to turn and face away from intruding divers rather than swim away.

While they are awkward swimmers, frogfishes are superbly adept ambush predators. When on the hunt they remain almost perfectly still as they extend the “lure” that is connected to the almost invisible first ray of their dorsal fin and wiggle it about to attract their prey of small fishes. This lure typically consists of a lumpy globule on the end of a nearly invisible fishing-pole like ray. Where a human fishermen is somewhat blinded at the surface of the water, frogfishes have the ability to direct the lure towards their prey and following the action with their eyes. They also manipulate the lure to appear life-like and with the already remarkably similar resemblance to animals such as worms, crustaceans and fishes, the illusion is complete and the ploy often results in a successful baiting.

Scientists have video taped the lightening speed at the moment of attack when the frogfish lunges at and engulfs its prey. The action takes place much to fast for human eyes to follow. As it makes its move a frogfish opens its suddenly enormous mouth as wide as it can as quickly as it can creating a pressure differential in the surrounding water. The near vacuum helps the fish suck in the surrounding water and the prey in an incredibly fast act. This feeding technique is known as “gape and suck,” and all the action occurs in less than one-hundredth of a second! If lost, the lure can be regenerated, but the process is not a fast one.  

Frogfishes would win very few races in the world of fishes as their stocky bodies are propelled by a stumpy tail. Frogfishes also move by using jets of water squirted from their mouths. In addition, their pectoral and pelvic fins have evolved into “flattened hands” that they use to prop themselves when the fishes rest and to assist them when they “walk” across the sea floor. When moving across the bottom frogfishes alternate the forward movement of their pectoral fins in a tetrapod-like walk or they can move both pectorals forward at the same time, using the fins like humans use crutches to propel themselves sluggishly forward. In addition, the highly modified pelvic and pectoral fins are capable of grasping the surrounding substrate. This adaptation helps frogfishes hold still as they attempt to ambush their prey.

Giant frogfish occur in the Indo-Pacific, Eastern Pacific, Red Sea and the waters of South Africa all the way to Panama, and of, course, in the Hawaiian Islands. As its common name suggests, giant frogfish are bigger than most other frogfishes. Full-grown adults can reach a length of 15 inches. Giant frogfish are bottom dwellers that are usually found in lagoons and in reef communities.

This week’s POTW was created with a Nikon D2x camera and a 105 mm lens. I used a pair of Ikelite DS 125’ strobes to light the shot.

I hope you enjoy this week’s POTW!

See you next week,

Marty