Giant Frogfish- Facts and Photographs

Antennarius commerson Giant frogfish , Commerson's Frogfish

The Giant frogfish or Commerson’s frogfish, Antennarius commerson is one of the more unusual fishes found on coral reefs. They are exceptionally well camouflaged and can resemble a sponge, coral or a rock.

APPEARANCE

The body colour varies greatly ranging from black to white with just about any colour in between. They have the ability to change colour over a few weeks to match their surroundings and their camouflage is excellent. I have been on a dive where a giant frogfish has been pointed out to a group of divers by pointing at it from a few inches away. Some of the divers have not seen it despite looking straight at it from a distance of two or three feet. The skin is covered with warty protrusions and colour variations and this adds to the effect of making the giant frogfish look exactly like a sponge or rock or coral depending on its coloration.

The first dorsal fin is modified into an appendage that has a lure on the end that resembles a small fish or shrimp and is used as a lure to attract prey. The pectoral fins and the pelvic fins are used to stabilise the frogfish on the substrate and are used to hop across the bottom in an ungainly fashion.  The rear section of the dorsal fin is usually folded at an angle to enhance the effect of resembling a sponge. They have an extremely large mouth that can  expand to allow the giant frogfish to swallow prey almost as large as its self. The giant frogfish grows up to 38 cm in length. The specimen in the images is about as big as they get and was photographed on Octopus Reef in Dar es Salaam, Tanzania.

IN THE WILD

The Giant frogfish is usually seen in areas with a large number of sponges in it , but they are incredibly versatile in camouflaging themselves. Their heads have a distinctive shape and when diving if you wish to see one it is best to look for this shape. They also often have a tendency to curve their body slightly and to fold the dorsal fin downwards. They are however not easy to spot. When they spot a diver they usually stop moving their lure and will sit dead still without moving.

After awhile they gently open and close their mouths but I have never seen one resume using its lure.  They have no swim bladder and as a result are poor swimmers. If they need to move more than a few feet they take in water through their mouths which is expelled through the gills to propel them forwards. To move short distances they “walk” using their pectoral and pelvic fins.

Antennarius commerson Giant frogfish , Commerson's

HABITAT

The giant frogfish is found across the tropical Indo Pacific area.

 

DIET

The giant frogfish are ambush predators and will eat any passing fish or crustacean that they can fit in their mouths including other frogfish. The prey is swallowed whole in one very fast motion. They have no teeth with which to latch onto the prey. As the frogfish opens its mouth so water and the prey are sucked in.

REPRODUCTION

Giant frogfish are usually solitary but gather in mating season. The female begins to swell two days before the mating and the usually smaller male approaches and nudges at the female. The female rises up in the water table and releases the eggs which are fertilised by the male. The eggs then float for a period and settle, hatching into miniature frogfish.

Antennarius commerson Giant frogfish , Commerson's

AQUARIUMS

Giant frogfish are kept in some public  aquariums but will eat anything that fits in their mouths so care has to be taken in choosing their tank mates.

GIANT FROGFISH CLASSIFICATION

Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Lophiiformes
Family: Antennariidae
Genus: Antennarius
Species: Antennarius commerson

IMAGES

 

LITERATURE CITED

 

 

The Reef Guide: Southern Africa’s East and South Coasts
Dennis King and Valda Fraser

 

EQUIPMENT USED

Canon 7D

Ikelite 7D Housing

Twin Ikelite DS 161 Strobes

Flat Ikelite Lens Port

Ikelite Dual Synch Cord 

Ikelite 5.1 inch Port body

 

 

About The Author

Profile photo of Alan Sutton

Alan Sutton is an underwater photographer and writer at Seaunseen.

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