Steady as a Rock, 
Fast as Lightning 
Text and photographs by David B. Grobecker 
Swimming along a coral enclave in 
search of food, a small reef fish spots 
a prey item near a small coral- 
encrusted rock. The fish moves in for 
what seems an easy kill, but suddenly 
it mysteriously disappears. In a 
matter of milliseconds, this predator- 
turned-prey has been captured and 
consumed by a warty anglerfish 
( Antennarius maculatus). The small 
coral outcropping was in reality the 
cryptic anglerfish, and the apparent 
prey was part of a modified fin spine, 
which the five-inch angler dangled in 
front of its mouth as bait. 
The warty anglerfish, so named 
because of the wartlike bumps that 
cover its body, inhabits the coral 
reefs of the Indo-Australian 
archipelago. The species belongs to 
the family Antennariidae, one of 
sixteen families of the order 
Lophiiformes, a curious assemblage 
of fishes characterized most 
strikingly by the anterior spine of 
their dorsal fin. This spine is placed 
on the end of the snout and modified 
to serve as a luring apparatus. At the 
tip of the flexible spine, or illicium, 
hangs a fleshy bait, or esca, which 
takes many different forms and 
mimics in appearance and movement 
such creatures as worms, shrimps, 
and even small fish. A shrimplike 
esca, for example, is maneuvered to 
simulate the quick, backward-darting 
motion of a swimming shrimp, while 
a fishlike esca is made to ripple as it 
is pulled through the water, 
mimicking the lateral undulations of 
a swimming fish. (If the “bait” is 
nipped off, a nearly exact replica 
rapidly regenerates. Growth is 
obvious within a few days, and the 
esca may be fully replaced within 
two weeks.) 
The feeding strategy of these 
piscivorous fish consists of wriggling 
the lure while maintaining the 
immobile, inert appearance of a 
sponge- or coralline-encrusted rock. 
When the anglerfish is not luring, 
muscles inside the esca contract and 
the illicium is laid back on top of the 
head in an inconspicuous position. 
Luring behavior is activated by visual 
and tactile stimulation. Once the 
prey is enticed within striking range, 
the angler suddenly expands its 
mouth cavity, creating a negative 
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