pressure that sucks in both the victim 
and a large volume of water. This 
engulfment is so quick that all a 
human spectator sees is a blur. But 
by using high-speed cinematographic 
equipment to record and later slow 
the action down, I was able to 
observe closely the fish’s unusual 
method of feeding. 
A feeding warty anglerfish can 
expand its mouth to twelve times the 
volume of the mouth when closed. 
The speed at which it expands its 
mouth and engulfs its catch is 
amazingly rapid. Analysis of a film 
sequence shot at 1,000 frames per 
second revealed that the warty 
anglerfish was capable of engulfing 
prey in fewer than six milliseconds, 
making it one of the fastest-feeding 
vertebrates ever recorded. 
The anglerfish is able to force an 
entire prey item directly into its 
stomach in only about twice as much 
time as it takes to engulf the prey. 
Clamping its modified opercular 
openings shut with its pectoral fins, 
the fish swallows the entire mouthful 
of water and prey. After the prey is 
safely in the stomach, the ingested 
water is forced out through the front 
of the mouth and the now unclamped 
opercular openings. Large prey items, 
sometimes larger than the anglerfish 
itself (see radiograph, right), are 
transported to the stomach in a 
conventional way, by the raking 
action of well-developed pharyngeal 
teeth. 
When it comes to diet, the 
anglerfish is less than choosy. The 
warty anglerfish is mostly piscivorous 
but takes an occasional crustacean. 
The goosefish Lophius americanus , 
recorded to reach nearly four feet in 
length, is kijown to have eaten 
cormorants and herring gulls, while 
one dissected Sargasso angler 
( Histrio histrio) held sixteen young 
of its own species inside its huge, 
expandable stomach. 
In 1837, the French naturalist 
Anglerfish of the genus Antennarius 
are able to engulf whole prey with 
body length considerably larger 
than their own, as demonstrated 
in this radiograph of an angler 
with a scorpionfish in its 
expandable stomach. 
Achille Valenciennes provided an 
intriguing, if anecdotal, discussion of 
the foraging behavior of an 
anglerfish: 
They have the ability to inflate their 
bodies like a balloon by gulping air or by 
filling their membranous stomachs with 
water . . . the position of the paired fins 
gives them the appearance of having 
four feet. . . . The tiny gill openings, 
represented only by a round aperture 
hidden in the axil of the pectoral-fin 
lobe, enable them to remain out of water 
for extended periods of time. This, in 
turn, enables them to crawl out over 
seaweed and mud. Thus, they pursue 
their prey. . . . 
The ability to remain out of water 
is questionable, but these fish do use 
their armlike and leglike pectoral and 
pelvic fins to crawl, walk, and even 
gallop. They have also evolved 
another form of locomotion unusual 
for fish: jet propulsion. The 
anglerfish sucks water into its mouth 
and forces it out through the long, 
tubular opercular openings. Then, 
using its pectoral fins as planing 
devices and its tail as a rudder, the 
fish maneuvers about its reef habitat. 
Warty anglerfish observed in 
aquariums aggressively defend their 
feeding sites against intruding 
anglerfish. A fish positions its body 
between its site and the invader, 
while at the same time engaging in 
elaborate display behavior. Spread 
fins, blushed colors, and a gaping 
mouth are accompanied by an 
intense shaking of the entire body. 
This intimidating display is usually 
enough to repel the unwelcome 
trespasser, and the anglerfish is once 
again free to turn into a rock. 
The warty anglerfish uses great 
energy-saving tactics in its quest for 
food. The combined structural and 
behavioral adaptations, including the 
evolution of an ultrafast feeding 
mechanism, have played an 
important part in the success of this 
aggressive mimic. □ 
52 
