> Subphylum Vertebrate > fishes
learn only 3 things about them ...
| They are fishes that go fishing! They use lures to attract
They are awkward swimmers, but they have the fastest mouth!
to spot: they resemble sponges, rocks. So watch your step!
seen? These rotund fishes are sometimes seen on some of our shores. They
are probably quite common and often simply overlooked as they are
extremely well camouflaged.
What are frogfishes? Frogfishes
belong to the Family Antennariidae. According to FishBase,
the family has 12 genera and 41 species. These
fishes were previously called anglerfishes, a much more appropriate
name for these ambush predators. But anglerfish is now a common name
reserved for deep sea fishes that also use a lure to attract prey
within their reach.
Features: Those seen about 6-10cm
long, can grow to 18cm. The frogfish has a globular body that can expand greatly. A handy
feature that allows the fish to swallow prey as large as itself. Not
a fast swimmer, the frogfish usually lies motionless near coral rubble,
blending perfectly with its surroundings. Here it waits to ambush
passing prey. It doesn't have scales and instead, has a loose prickly
skin. Covered with filaments and fleshy bits, it looks just like an
algae-covered rock. The frogfish has tube-like gill openings under the base of its pectoral
fins. This prevents exhalations from betraying its presence. It is
said that the openings can also be used for jet-propelling. Its eyes
are at the top of its head. Gill openings are reduced to small round
Frogfishes come in a wide variety of colours and patterns. Some species
are brightly coloured to mimic sponges or other colourful reef creatures.
According to Kuiter, the young of some species of frogfishes sometimes
look like poisonous nudibranchs.
Sometimes mistaken for stonefish
and scorpionfish. Unlike those fishes, the frogfish is harmless. Here's more on how
to tell apart fishes that look like stones.
Changi, Jun 08 |
A lure that draws
prey closer to the mouth
Lure and bright markings in the mouth.
Sisters Island, Aug 07
with a lure: The
frogfish literally lures prey to come closer. The lure is at the top
of its head, just above its very large, upward facing mouth.The lure
is made up of the first spine of the dorsal fin. The spine is modified
into a rod or stalk (called the illicium) tipped with a fleshy, fluffy
or otherwise attractive bit (called the esca). This bit is wriggled,
jerked and waved about so it appears to be a helpless and tasty little
morsel. While the fish itself remains motionless, looking like just
another lump of rock or other harmless thing. Unsuspecting creatures
that attempt to eat the lure are instead eaten by the frogfish! Each
frogfish species usually targets a specific prey and each species
has a lure that resembles something the targeted prey would find tasty.
When not in use, the lure is safely flattened against the head.
The victim is usually swallowed whole in one gulp of the frogfish's
huge mouth. The frogfish can hugely expand its mouth in less than
a second, making it among the fastest capture in the animal kingdom.
What do they eat: Frogfishes generally
eat other fishes although some temperate species eat crustaceans.
They may even eat other frogfishes, including their potential mates!
'Climbing' on long seagrass with its 'paws'.
Pulau Semakau, Apr 11
Tuas, Aug 04 |
Pulau Semakau, Sep 05
|Fish with arms?! The frogfish
has another unusual feature: limb-like pectoral fins with an elbow-like
joint. These look almost like 'paws'. It uses these fins almost like
arms and hands, to grip the surface and 'walk' slowly about (more
of a waddle actually). It also has clasping pectoral fins under its
Frogfish babies: A frogfish mother
lays thousands of eggs embedded in a large floating gelatinous mass
called an 'egg raft' or 'veil'. Lophiocharon species are known to brood and care for their eggs. It is believed that the female lays eggs directly onto the side of the male, the eggs attached by sticky threads. The father then look after the eggs by curling his body around the eggs, and folding his dorsal, caudal and pectoral fins over the egg mass to partially conceal them. One spotted-tail frogfish was seen to do that.
According to FishBase the father fish carries egg clusters attached to the side of his body,
"either as brooding strategy or as aid in luring other fish for
food". Motionless, his eggs will indeed look like a tasty snack
on a stone. Any potential egg-snackers will of course be in danger
of becoming a snack for papa frogfish!
Unusual frogfishes: While most
frogfishes are bottom-dwelling, one species (Histrio sp.) floats
among sargassum seaweed. Another species, the Brackishwater frogfish
(Antennarius biocellatus) inhabits brackish and even totally
on Singapore shores
Antennariidae recorded for Singapore
Wee Y.C. and Peter K. L. Ng. 1994. A First Look at Biodiversity
*Lim, Kelvin K. P. & Jeffrey K. Y. Low, 1998. A Guide to the Common
Marine Fishes of Singapore.
+Other additions (Singapore Biodiversity Records, etc)
seen awaiting identification
caudimaculatus=**Antennarius commerson (Commerson's frogfish)
Antennarius chironectes=**Antennarius pictus (Painted frogfish)
Antennarius hispidus (Shaggy frogfish)
+Antennatus nummifer (Spotfin frogfish)
*Lophiocharon trisignatus (Spotted-tail
- Tan Tsu Soo & Toh Chay Hoon. 31 October 2019. Rediscovery of spotfin frogfish (Antennatus nummifer) in Singapore.Singapore Biodiversity Records 2019: 141-142 ISSN 2345-7597, National University of Singapore.
- Tan Heok Hui. 29 August 2014. Egg brooding behaviour of the spot-tail frogfish, Lophiocharon trisignatus. Singapore Biodiversity Records 2014; 237-238.
- Wee Y.C.
and Peter K. L. Ng. 1994. A First Look at Biodiversity in Singapore.
National Council on the Environment. 163pp.
- Allen, Gerry,
Fishes of South-East Asia: A Field Guide for Anglers and Divers.
Periplus Editions. 292 pp.
- Kuiter, Rudie
H. 2002. Guide
to Sea Fishes of Australia: A Comprehensive Reference for Divers
New Holland Publishers. 434pp.
Ewald and Robert Myers. 2001. Coral
Reef Fishes of the World
Periplus Editions. 400pp.