Hairy, Painted, Warty, or Psychedelic: WHAT AM I?
Kathrin Landgraf-Kluge
A master of disguise lumbers awkwardly across the sandy bottom, the rod stemming from its head swaying precariously from side to side as it waddles along. But what could this strange and ungainly creature be? Keep reading to find out...
Searching for the elusive frogfish is an obsessive and exciting treasure hunt for many a diver. Belonging to the family of anglerfish (family: Antennariidae, order:Lophiiformes), frogfish are found in tropical and subtropical oceans across the world, with the greatest diversity of species found in the highly biodiverse Indo-Pacific region. If you’re keen on finding a frogfish, the 49 different species of frogfish described can be found at a depth of up to 100m and commonly stay at the ocean floor around reefs of coral or rock (though the sargassum frogfish that has a preference for clumps of drifting seaweed). Indonesia is a hotspot for frogfish and if you’re looking for a guaranteed frogfish sighting, then we highly suggest you check out Lembeh Strait in North Sulawesi.
Photo: Kathrin Landgraf-Kluge
But what makes this curious creature such a master of disguise? In contrast to other fish species, frogfish have an atypical, stocky form. Their a short body and upturned mouth contributes to a rather unusual frog-like appearance, that is further contrasted to other fish species in that their skin is scale-less. They vary in length from species to species, ranging from the miniscule 2.5 cm to 38 cm with a plump, high-backed and unstreamlined body shape. The largest of the frogfish species is the Commerson’s frogfish (Antennarius commerson), more commonly known as the giant frogfish. Reminiscent of a large piece of sponge, the coloration of this giant can be extremely variable including grey, yellow, red, green or black color (as shown in the image below).
These bumbling beauties are famed for their clumsy walk (if you haven’t already watched “Two hairy frogfish take a walk” on Youtube, then go and watch it ASAP). Frogfish typically do not move very much and if they do, they move very slowly. In fact, they prefer to lie on the seafloor, waiting for prey to enter the nearby vicinity. They rarely swim but rather move over the sea floor by what seems like “walking” using their two unique pectoral fins, (which is how they get their name).
Photo: Kathrin Landgraf-Kluge
The frogfish is a camouflage king. Because of their unusual shape, colour, and special skin texture, frogfishes blend seamlessly into their surroundings. Many frogfish species, including the giant frogfish, can change their coloration within a few weeks. Some species, such as the Hairy Frogfish (Antennarius striatus) or the Shaggy Frogfish (Antennarius hispidus), are covered in spinules or other appendages. But this camouflage isn’t just used to deter predators, these crafty little critters even use their appearance to lure in prey using a behaviour called aggressive mimicry. Dependent on their location, frogfish will imitate their surrounding environment; some resemble stones or coral, while other species look like sponges, tunicates or even sea urchins.
But perhaps the most intriguing characteristic of frogfish, is the presence of the so called illicium or “rod” which is topped with the esca or “lure” and placed right above their mouth. Dependent on the species, the esca can have different forms, adapted to resemble the form of fish, shrimp or tubeworm. By moving the illicium together with the esca, they mimic a potential meal to their prey.
Photo: Kathrin Landgraf-Kluge
Though they feed mainly on crustaceans or other fish, frogfish have also been known to exhibit cannibalistic behavior. Like a fisherman with his rod, when potential prey approaches, frogfish begin to move the illicium and esca to lure the prey into their immediate proximity. The frogfish strike is sudden and within milliseconds it is all over. When the prey is close enough, the frogfish opens its jaws, enlarging the mouth cavity up to 12-fold of its normal size. The unknowing prey is vacuumed into the mouth along with the water, in a move so fast that it is hard to observe without slow-motion filming.
If you have ever been fortunate enough to participate in a blackwater dive, then you will may be aware of the epic cuteness of miniscule frogfish babies. The process of reproduction of frogfish is still not fully understood; most species are free-spawning and female frogfish can release up to 180,000 eggs at a time. For most species, the fertilized eggs drift in a gelatinous mass or long ribbon on the surface. After hatching, the frogfish larvae live planktonically for one or two months. Following this period, though still tiny in size (15 to 28mm), they already have the complete form of adult frogfish. That is when they start their lives on the seafloor and often mimic the appearance of poisonous nudibranchs or flatworms which helps them to protect themselves from predators.
Photo: Kathrin Landgraf-Kluge
To sum it up, frogfish are very special fish in many ways. It’s no surprise really that this camouflaged and clumsy creature is a must-add to the bucket list of almost every diver and underwater photographer. I love them too… I mean, how can you not?!