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Frogfish Behavior

Colors and Camouflage
Reproduction
Locomotion

 

Feeding behavior

Aggressive Mimicry - Luring prey - Gape and Suck
Print version frogfish behavior - Diese Seite in Deutsch

Aggressive Mimicry

The most interesting aspect of the frogfish, apart from his prefect camouflage is the way he attracts his prey. Other fish lie in wait until the prey swims close to their mouth (lie-in-wait predation), but the frogfish (or anglerfish) lures the prey (fish, crustaceans) actively to where it can strike. The lure mimics food animals like worms, small shrimps or small fish. The prey approaches to catch the lure and then is engulfed by the waiting frogfish (see a video). This strategy is called aggressive mimicry.

Painted frogfish (Antennarius pictus) juvenile - stretches its lure in front of the mouth (long rod)
Painted frogfish (Antennarius pictus) juvenile - stretches its lure in front of the mouth (long rod)
Painted frogfish (Antennarius pictus) juvenile - stretches its lure in front of the mouth (long rod)
Painted frogfish (Antennarius pictus) - Detail of the rod and lure above the head
Painted frogfish (Antennarius pictus) juvenile - stretches its lure in front of the mouth (long rod)
Painted frogfish (Antennarius pictus) - luring directly above a hole in the ground - Video
Baby Painted frogfish (Antennarius pictus) starts luring
Baby Painted frogfish (Antennarius pictus) starts luring
Baby Painted frogfish (Antennarius pictus) starts luring
Baby Painted frogfish (Antennarius pictus) luring
Baby Painted frogfish (Antennarius pictus) starts luring
Baby Painted frogfish (Antennarius pictus) luring
Baby Painted frogfish (Antennarius pictus) starts luring
Baby Painted frogfish (Antennarius pictus) luring
Baby Painted frogfish (Antennarius pictus) starts luring
Baby Painted frogfish (Antennarius pictus) luring
Baby Painted frogfish (Antennarius pictus) starts luring
Baby Painted frogfish (Antennarius pictus)opens the mouth to swallow
Painted frogfish (Antennarius pictus) luring
Painted frogfish (Antennarius pictus) luring
Painted frogfish (Antennarius pictus) luring
Painted frogfish (Antennarius pictus) luring
Painted frogfish (Antennarius pictus) luring
Painted frogfish (Antennarius pictus) luring

Of course not all prey is attracted by the lure. A more passive approach is the excellent camouflage of the frogfishes. Many animals just mistake a frogfish for a sponge, come too close and are swallowed. I have actually seen on various occasions, how small gobies flittered over the body of a frogfish sitting in a sponge, without being aware of the danger of getting eaten (image).

Other fishes will perceive the camouflaged frogfish as perfect shelter and approach too close. Frogfishes often look like algae covered rocks. In coral reefs there isn't really a plentiful supply of algae for herbivore fishes. These fishes will approach a frogfish because they perceive a good feeding ground and are then caught. Because no herbivore fishes can eat plants surrounding the frogfish (they all get caught) these plants will grow extensively and even more fishes are attracted to the ambush site.

The frogfish sometimes also actively stalks prey, I have seen a frogfish (Antennarius striatus) trying to catch a small flounder by slowly sneaking towards it. It was trying to get the flounder into striking distance. The strike zone is about one frogfish body length. Click on thumbnail for enlargement.

Hairy frogfish (Antennarius striatus) - waits close to a burrow of a goby
Hairy frogfish (Antennarius striatus) - waits close to a burrow of a goby
Giant frogfish (Antennarius commerson) - two frogfishes in a large sponge
Giant frogfish (Antennarius commerson) - two frogfishes in a large sponge
Hairy frogfish (Antennarius striatus) - stalks the juvenile flounder (to the left)
Hairy frogfish (Antennarius striatus) - stalks the juvenile flounder (to the left)

Luring prey

Click here for videos of frogfishes luring

Frogfishes mainly eat fishes and crustaceans (shrimps and crabs). They can swallow items of prey that are twice as large as them (see a video). Luring techniques vary depending on the surrounding the frogfish lives in. A frogfish (for example Antennarius striatus) living mainly on sand often has a lure that reaches close to the ground, so it can move the lure at the entrances of burrows or entice benthic animals like flounders to come closer. A frogfish living exposed on sponges or corals (for example Antennarius commerson) will lure more often above its head and might have a longish lure. A frogfish living hidden in crevices (for example Antennatus nummifer) often is small and has a small lure, more like a white ball and will stretch it in front of its head or just above.

Each frogfish species moves the rod (illicium) with its lure (esca) in a special pattern to attract the attention of potential prey. For example the warty frogfish (Antennarius maculatus) moves its lure in wavy lines either above the head or directly in front of the mouth close to the ground, the lure is doing a circle. The giant frogfish (Antennarius commerson) is moving its lure up and down in jerky movements. A study in luring behavior by S. Michael also showed, that a frogfish can vary its angling technique. A coinbearing frogfish (Antennatus nummifer) he observed used three different luring patterns - lifting the lure and vibrating the esca, holding the lure still in front of the mouth and throwing the angel rapidly back and forward.

The frogfish on the following photos all have long lures. Click on thumbnail for enlargement.

The 6 photos below show the Painted Frogfish (Antennarius pictus) moving its lure

the Painted Frogfish (Antennarius pictus) moving its lure

the Painted Frogfish (Antennarius pictus) moving its lure

the Painted Frogfish (Antennarius pictus) moving its lure

the Painted Frogfish (Antennarius pictus) moving its lure

the Painted Frogfish (Antennarius pictus) moving its lure

the Painted Frogfish (Antennarius pictus) moving its lure

The pictures (below) to the left and right were taken at the same dive site but a year apart. They are from two different species (different lure!) but show the same behavior.
Painted frogfish (Antennarius pictus) - surrounded by cardinalfishes. They are not yet close enough to catch them
Painted frogfish (Antennarius pictus) - surrounded by cardinalfishes. They are not yet close enough to catch them
Painted frogfish (Antennarius pictus) - surrounded by cardinalfishes. They are not yet close enough to catch them
Painted frogfish (Antennarius pictus) - mouth on top

Small Giant frogfish (Antennarius commerson) - surrounded by Banggai cardinalfishes.
Hairy frogfish (Antennarius striatus) - hiding between sea urchins to catch some cardinalfishes. It probably is imitating the spines of the sea urchin.
Hairy frogfish (Antennarius striatus) - hiding between sea urchins to catch some cardinalfishes. It probably is imitating the spines of the sea urchin.
Hairy frogfish (Antennarius striatus) - hiding between sea urchins to catch some cardinalfishes. It probably is imitating the spines of the sea urchin.
Hairy frogfish (Antennarius striatus) - putting down one foot on the spines of the sea urchin
Hairy frogfish (Antennarius striatus) - hidden under the tentacles of a sea cucumber
Hairy frogfish (Antennarius striatus) - hidden under the tentacles of a sea cucumber

Frogfishes even lure in the dark. Although the lure and esca can not be seen during night, the potential prey can feel the vibrations which are transmitted through the water and attack what seems to be an incautious animal.

Frogfishes also employ chemical attractants. This is of importance to frogfish that forage at night like the hairy frogfish (Antennarius striatus). This frogfish also enlarges his esca by 35% when actively luring. The hairy frogfish, a juvenile, about 9cm large, on the following 9 photos (also possible to see as a short video) was walking about and luring during about 10 minutes, checking out several goby burrows but with no success. During some time it stretched the lure out in front while walking, then again it was moving the lure over its head in complicated patterns. It was interesting to observe the lure, which made wavy movements, then again was rolled up and nearly hidden. Click on thumbnail for enlargement.

Hairy frogfish (Antennarius striatus)

Hairy frogfish (Antennarius striatus) Hairy frogfish (Antennarius striatus)

Hairy frogfish (Antennarius striatus)

Hairy frogfish (Antennarius striatus) Hairy frogfish (Antennarius striatus)

Hairy frogfish (Antennarius striatus)

Hairy frogfish (Antennarius striatus) Hairy frogfish (Antennarius striatus)

Small frogfishes often prefer shallow water and live hidden in crevices between corals and among rubble. Hiding in such a way they avoid being preyed on by larger fishes. Smaller frogfishes probably don't use their lures as much as larger frogfishes to attract prey. Several of these frogfishes have very small lures (like Antennatus coccineus) or one that is nearly not discernable (like Antennatus tuberosus). The following photos show frogfishes with short rods and small lures (a small white dot). The rod is stretched out in front and not moved much. Click on thumbnail for enlargement.

Antennatus dorehensis - has a very small lure and a thin rod
Antennatus dorehensis - has a very small lure and a thin rod
Spotfin frogfish (Antennatus nummifer) - small white lure just above the eyes
Spotfin frogfish (Antennatus nummifer) - small white lure just above the eyes
Antennatus sp. - luring between sea urchins, to the left a small boxfish, its intended prey
Antennatus sp. - luring between sea urchins, to the left a small boxfish, its intended prey

Because the esca acts as a bait it is apparently highly susceptible to loss or damage by attacks or nibbling of potential prey as well as predators. Therefore some frogfish (for example Antennarius pauciradiatus or Antennarius randalli) have a pocket-like aperture formed by the membrane between the second and third dorsal spine which is used to protect the esca. Frogfish can regenerate their lure but might undergo a time of fasting until completion. It seems to take about 4 to 6 months to fully regenerate a lure.

Sometimes a predator also catches a frogfish. As the photos below show, the frogfish is inflating its body by swallowing water, so it is quite difficult for the predator (here a lizardfish) to swallow it. The photographer Stephane Bailliez wrote: I stayed around for more than 30mins while the lizardfish was stuck with this annoying prey. It tried a couple of times to do a quick release / catch in order to rotate it and thus tried different angles.

The lure of this Hairy frogfish (Antennarius striatus) has been severed, probably eaten by intended prey
The lure of this Hairy frogfish (Antennarius striatus) has been severed, probably eaten by intended prey
The lure of this Giant frogfish (Antennarius commerson) has been eaten but has grown back, only quite shorter than before
The lure of this Giant frogfish (Antennarius commerson) has been eaten but has grown back, only quite shorter than before
The lure of this Painted frogfish (Antennarius pictus) is very short and slightly bent, probably regenerated after been nibbled
The lure of this Painted frogfish (Antennarius pictus) is very short and slightly bent, probably regenerated after been nibbled
Detail of the lure of the Hairy frogfish (Antennarius striatus) - you can see, that it is regenerating - Video of the frogfish trying to lure
Detail of the lure of the Hairy frogfish (Antennarius striatus) - you can see, that it is regenerating - Video of the frogfish trying to lure
A Marble-Mouthed Frogfish (Lophiocharon lithinostomus ) with a lure which must have broken so it grey back bifurcated
A Marble-Mouthed Frogfish (Lophiocharon lithinostomus ) with a lure which must have broken so it grey back bifurcated
Copyright Esteban Cervantes
 
Frogfish being eaten by lizardfish
Frogfish being eaten by lizardfish
Copyright Stephane Bailliez
Frogfish being eaten by lizardfish
Frogfish being eaten by lizardfish
Copyright Stephane Bailliez
Frogfish being eaten by lizardfish
Frogfish being eaten by lizardfish
Copyright Stephane Bailliez

There is a group of frogfish species, which have no or a much reduced lure. The newly (2008) discovered frogfish species Histiophryne psychedelica (Ambon Frogfish) seems to block off the entrance to holes or crevices and thus entraps its prey inside (reference). It would be interesting to investigate if other nearly rodless frogfishes like Histiophryne bougainvilli or Histiophryne cryptacanthus also employ a similar behavior of predation.

Frogfishes also have a small small white skin flap or knob just above the mouth. I have observed this flap on several frogfish species, it is not always very prominent, but mostly of a white color. I haven't found any references to it in literature. I think, this is probably an additional enticement for small animals to go near the mouth!

Antennarius hispidus - Detail of the filamentous skin flap above the mouth
Antennarius hispidus - Detail of the filamentous skin flap above the mouth
Antennarius pictus - Detail of the whitish skin flap above the mouth
Antennarius pictus - Detail of the whitish skin flap above the mouth
Antennarius commerson - Detail of the white skin flap above the mouth
Antennarius commerson - Detail of the white skin flap above the mouth
 
Antennarius maculatus - Detail of the whitish skin flap above the mouth
Antennarius maculatus - Detail of the whitish skin flap above the mouth
 

The Deep-sea anglerfishes even have a glowing lure (bioluminescence produced by symbiotic bacteria) decorated with filaments or branches that also glow in the dark. These frogfish have a massive mouth and razor-sharp teeth. The lure can be four to five times longer than the fish itself and some anglerfishes of the family Linophrynidae (Leftvents) even have barbels on their chin that also generate light and look like a hanging basket.

Gape and Suck

Hairy Frogfish (Antennarius striatus) has caught a flounder but is unable to swallow the fish because it is too large

Hairy Frogfish (Antennarius striatus) has caught a flounder but is unable to swallow the fish because it is too large. After about 45 minutes the frogfish spat the flounder out, it was dead by then. Tropical frogfishes have no teeth, so they can't tear a fish into smaller pieces. Either swallow whole ar not at all.
Copyright Matthew Oldfield - more images of this frogfish (Flickr)

Antennarius pictus - catching the fish
Antennarius pictus - catching the fish
Copyright Jeffrey Low
Antennarius pictus - catching the fish
Antennarius pictus - sucking it in
Copyright Jeffrey Low
Antennarius pictus - catching the fish
Antennarius pictus - with a large belly
Copyright Jeffrey Low
Antennarius pictus
Antennarius pictus
Copyright Hung Chi Feng
Antennarius pictus
Antennarius pictus
Copyright Hung Chi Feng
 
Antennarius maculatus - Clown frogfish luring
Antennarius maculatus - Clown frogfish luring
Foto Johanna Gawron
Antennarius maculatus - Clown frogfish luring
Antennarius maculatus - the Clown frogfish has caught a fish
Foto Johanna Gawron
Antennarius maculatus - Clown frogfish luring
Antennarius maculatus - the Clown frogfish swallowing a fish
Foto Johanna Gawron

When feeding, the frogfish expand the oral cavity. The lower jaw is lowered and the upper jaw is expanded. They engulf their prey with a reflex that sucks it in by creating suction pressure inside the mouth (increase up to 12 times in volume by expansion of the oral cavity). This is the fastest "gape and suck" of any fish, it takes only a six-thousandths of a second, which is faster than a scorpionfish or a stonefish (15 msec).

Frogfish hunting: luring, opening mouth, engulf the prey

They can actually catch a fish out of a school without the other fish noticing the disappearance. A frogfish will easily swallow prey that is larger than itself. It doesn't have teeth, because the prey is swallowed whole and not cut into pieces by the teeth. Click on thumbnail for enlargement.

Giant frogfish (Antennarius commerson) opens mouth to yawn
Giant frogfish (Antennarius commerson) opens mouth to yawn
frogfish opening its mouth. Photo by Martin  Buschenreithner
Giant frogfish (Antennarius commerson) opens mouth to yawn
frogfish opening its mouth. Photo by Martin  Buschenreithner
Giant frogfish (Antennarius commerson) opens mouth to yawn
frogfish opening its mouth. Photo by Martin  Buschenreithner
Giant frogfish (Antennarius commerson) opens mouth to yawn
frogfish opening its mouth. Photo by Martin  Buschenreithner
Giant frogfish (Antennarius commerson) opens mouth to yawn
frogfish opening its mouth. Photo by Martin  Buschenreithner
Giant frogfish (Antennarius commerson) opens mouth to yawn
Black warty frogfish (Antennarius maculatus) - opens mouth
Black warty frogfish (Antennarius maculatus) - opens mouth
Antennarius striatus - Hairy Frogfish opens mouth
Antennarius striatus - Hairy Frogfish opens mouth
Painted frogfish (Antennarius pictus) - opens mouth (like yawning)
Painted frogfish (Antennarius pictus) - opens mouth (like yawning)
Giant frogfish (Antennarius commerson) opens mouth to yawn
Giant frogfish (Antennarius commerson) opens mouth to yawn
Photo Johanna Gawron
Giant frogfish (Antennarius commerson) opens mouth to yawn
Giant frogfish (Antennarius commerson) opens mouth to yawn
Photo Johanna Gawron
Giant frogfish (Antennarius commerson) opens mouth to yawn
Giant frogfish (Antennarius commerson) opens mouth to yawn
Photo Johanna Gawron
X-ray of the jaw of the Marble-mouth frogfish - Lophiocharon lithinostomus
X-ray of the jaw of the Marble-mouth frogfish - Lophiocharon lithinostomus
Copyright California Academy of Sciences Ichthyology Section
X-ray of the jaw of the Indian Frogfish - Antennarius indicus
X-ray of the jaw of the Indian Frogfish - Antennarius indicus
Copyright California Academy of Sciences Ichthyology Section

X-ray of the jaw of the Bloody frogfish - Antennatus sanguineus
Copyright California Academy of Sciences Ichthyology Section

The frogfish is sometimes seen, opening its mouth and yawning. But only on two occasions I have seen how a frogfish actually eats its prey (see a video). Actually everything happened so fast, that all I really saw was the shrimp in front of the frogfish and then the frogfish moved and the next thing I realized the shrimp was gone and the frogfish made swallowing movements. No wonder that the frogfish can eat fishes out of a school without the other fishes noticing!

Baby Warty Frogfish (Antennarius maculatus) swimming with open mouth
Baby Warty Frogfish (Antennarius maculatus) swimming with open mouth
frogfish opening its mouth. Photo by Martin  Buschenreithner
Baby painted Frogfish (Antennarius pictus) - opening its mouth
frogfish opening its mouth. Photo by Martin  Buschenreithner
Tiny Baby painted Frogfish (probably Antennarius pictus) yawning
frogfish opening its mouth. Photo by Martin  Buschenreithner
Yawning Frogfish-Baby (Antennarius pictus)
frogfish opening its mouth. Photo by Martin  Buschenreithner
Yawning Frogfish-Baby (Antennarius pictus)
frogfish opening its mouth. Photo by Martin  Buschenreithner
Yawning Frogfish-Baby (Antennarius pictus)
 

Even tiny frogfishes (the red fish on the pictures above is about 4mm long) open their mouth to "yawn".

What goes in must come out....

Antennarius pictus shitting
Antennarius pictus
Antennarius pictus shitting
Antennarius pictus
Antennarius pictus shitting
Antennarius pictus
Antennarius pictus shitting
Antennarius pictus
Copyright Kermi Sukirman
Antennarius commerson  shitting
A. commerson
Copyright Rob van de Louw

DVD

My recommendation: A great DVD with coverage of the uncommon animals living in the Lembeh strait by Shark Bay Films "The Critter Trilogy" (John Boyle). Filmed entirely in Indonesia's Lembeh Strait in open water. Great coverage of frogfishes feeding and much more! Sold by www.electricsky.com

I identified all frogfishes (anglerfishes) to my best knowledge. Frogfishes are specially difficult to identify (see tips for identification) so mistakes are possible of course! Please write to me, if you have any questions. Latin names according to the newest scientific findings, ITIS Standard Report and Fishbase.


. Copyright Teresa Zubi