It is time to “Take a minute to Relax” again: A Hairy Frogfish (Antennarius striatus) wandering over the sandy bottom in Siaba Besar, one of the outstanding dive sites for critter hunting in the Komodo National Park in Indonesia. Wait a minute! Wandering like walking? Correct, this fish lacks a swim bladder. Angled fins allow them to “walk” or “hop” along the ocean floor. They can also move by expelling water through their gills. It’s like the frogfish is drinking its way forward and looks extremely funny as another froggy filmed once upon a time in the Philippines demonstrates willingly.
First this hairy frogfish (Antennarius striatus)
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Let’s talk about these weird and wonderful critters a little more. Frogfish, a.k.a. anglerfish, are part of the wide group of ambush predators. Somehow frogfishes stand out of the crowd turning them into the all-time favourites of divers and underwater photographers. Some call them ugly, but we find them fascinating not only for their locomotion. Frogfish have brought the art of „blending in“ to a whole new level. Granted the best camouflage can’t hide them once they start to move it, move it.
One, two, three, many frogfishes
There are around 46 different species of frogfish around the world. As their colouration varies, some are hard to distinguish. Generally, frogfish are stocky with big mouths and oddly shaped fins. Sizes vary from fingernail to football. Their chubby, high-backed, unstreamlined bodies are scaleless.
There isn’t one particular style or colour that unites them. Basically, anything goes as long as it serves their camouflage, usually a sponge or encrusted rock, but also soft corals or even seaweed (sargassum frogfish). They are masters of disguise, slowly changing their skin colour and texture to match their surroundings perfectly, even mimicking the oscula/pores of the sponges they often sit on or next to. Additionally, they cover themselves with other organisms such as algae or hydrozoa. Interestingly, Antennarius striatus sometimes comes with less hair and sometimes it lacks hair completely.
The odd one out
All frogfish lack a swim bladder. Found in most swimming fishes a swim bladder maintains buoyancy in a similar manner to a diver’s BCD. If they have to they can use jet propulsion (drinking themselves forward) as well as strokes of the caudal fin. For short distances, they use their pectoral and pelvic fins to walk over the ocean floor. All of these look rather odd or clumsy.
As they don’t want to give away their camouflage, frogfishes typically just lay and wait for prey. However, they make small adjustments to their position with their fins. When they spot potential prey, they follow it with their eyes.
Lure them in
Different species of frogfish have different lures (escae). Some resemble shrimps, others fishes, worms or tiny squids. Recent scientific discovery has shown the striated frogfish’s lure to be biofluorescent. No matter which style, frogfishes use them to attract prey.
As soon as it approaches roughly within the distance of seven body lengths, the frogfish starts to use its rod (illicium) and lure (esca) to get the prey closer. The esca doesn’t only look like the preferred food of the prey it is also moved in the same fashion.
This behaviour got them their name: anglerfish (Antennariidae). Frogfish live the definition of “aggressive mimicry”: “Self-concealment to fool prey organisms or the use of special appendages such as lures to bait prey.”
Once the prey is close enough, frogfish strike extremely fast. In as little as 6 milliseconds their mouth opens up to 12 times the size creating a strong sucking motion. Afterwards, they can close off the mouth without reducing the volume within. This is the most rapid engulfment of all vertebrates.
Fast strike, slow change
On the contrary, changing colour and texture takes some time. Over weeks they slowly adapt to new surroundings.
Frogfishes are found in almost all tropical and subtropical oceans and seas around the world, with the main exception of the Mediterranean Sea.
One group of frogfish has a relatively small number of large eggs that stay attached to the body during their development. The other group spawns a mass of small eggs that immediately floats away in ocean currents all by themselves. Hairy frogfish belong to the latter group.
Taxonomy / Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Lophiiformes
Suborder: Antennarioidei
Family: Antennariidae
Genus: Antennarius
Species: Antennarius striatus
From tiny critters to gentle giants: Take a Minute has them all
For more visual meditation and marine information, watch the whole playlist on our YouTube channel or browse through the different clips on our designated page „Take a Minute“ on this website.
