What do you think of if I told you to imagine one of the world’s most voracious predators? You might imagine a lone cheetah crouching in the tall grass, waiting to pounce on some unsuspecting gazelle. Maybe a pack of wolves spring to mind, working together to split the weakest of the heard. What you may not think of, is a small, blob shaped fish that can barely swim.
Although they may seem to lacking the features of most top predators, having no real defences apart from camouflage and being the opposite of streamlined, frogfish have evolved a unique survival strategy that have allowed them to be one of the reefs most dangerous inhabitants.
First of all, frogfish have unbelievable camouflage. They look almost identical to a sponge. You will need to be a very good spotter to find one yourself, the easier way to spot these amazing critters is by having an experienced local dive guide. Even if you do see one, it can be very difficult to know what you are actually looking at!
Although colour varies between the different species, two members of the same species can also look very different from each other. This is because frogfish can change the colour and pattern of their skin to better blend in with its surroundings. The skin texture also varies between species, some having smooth skin, while others are coated in warts or covered in algae like hair. If a frogfish decided it wanted to move to a new hiding spot, it could change its colouration to blend it with its new environment. While this does occasionally happen, frogfish tend to stick to one spot for a long time.
Their impressive camouflage is for one thing only, to lure unsuspecting creatures into the danger zone, which is around seven body-lengths distance. Frogfish are a part of the anglerfish family, a large family of fish with a characteristic growth from their heads that acts as a lure. The fishing rod of a frogfish is actually a modified dorsal fin, with additional flesh at the end to act as bait. Once any kind of prey gets within range, the frogfish will start flicking this bait up and down, hoping any unsuspecting animal takes the bait.
Once the prey is within range, the frogfish will suddenly open its jaw by up to twelve times its normal size, and in doing so, will create a vacuum and suck in the prey and all the water surrounding it. This hugely expanding mouth cavity allows the frogfish to eat prey almost as large as themselves, and their stomachs can even expand to accommodate meals larger than themselves. Their diets is usually a combination of fish and crustaceans, however, these voracious predators are not above eating other frogfish if one were to take the bait. Sometimes, their prey gets the better of them and their lure gets bitten off. If this happens, frogfish are able to grow a new lure.
Another thing that sets frogfish apart from most other fish is the way they move. Most fish are pretty confident swimmers, but frogfish prefer walking rather than swimming. Unlike most fish, they lack swim bladders, which means they are always negatively buoyant so swimming takes huge amounts of energy, and they are slow compared to other fish. Their pectoral fins have modified over time, and now work better as feet than fins. This slow walk also allows them to move relatively undetected around the reef. When the need arises, frogfish can move in a unique way, by sucking in water and pumping out of their gills in a similar manner as jet propulsion.
Their bizarre appearance, strange hunting tactics, and slow movement has made frogfish a popular photography subject for divers. There are species that can be great for macro and wide angle photography, but I think they are the most impressive in video form, although you may need to wait around for a while before they actually do anything.
Frogfish can be found throughout the tropics world-wide, however the highest diversity of species can be found within the coral triangle; Indonesia, The Philippines, Malaysia, Papua New Guinea, Solomon Islands and Timor-Leste. There are some incredibly rare species such as the psychedelic frogfish (pictured above), living in Indonesia. If you are lucky enough to spot one of these fascinating critters, it is very important that you don’t stress them by taking too many photos with an external strobe. They will not move as doing so will give away their camouflage, however the constant flashing will potentially damage their eyesight.
‘The Voracious Frogfish’ was written by Mike