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Carnivory hot buttons for carnivory part of Biology of Caribbean Coral Reefs website hot button for zooplanktivore part of BCCR hot button for spongivore part of BCCR hot button for corallivores & other cnidivores part of BCCR hot button for gorgonivores part of BCCR hot button for benthic invertebrate-eaters part of BCCR hot button for piscivores part of BCCR
This part of carnivory deals with piscivores, that is, with coral-reef organisms, including fishes, sharks, squids, and marine mammals, that include mainly fishes in their diets. Other topics relating to carnivory on coral reefs can be accessed via the icons.
 
 

Carnivory: piscivores (eaters of fishes): ambush piscivores

This section deals with piscivores that lie in wait on the reef waiting for fish prey to happen by. These predators are often camouflaged, visually or chemically, or both. Topics dealing with ROVING PISCIVORES and WOUNDED FISHES can be found in their own sections. Additionally, there is a section on COOPERATIVE HUNTING.

 
 
seahorse dive leader for Biology of Caribbean Coral Reefs website photograph of a short-nose batfish taken from a video

"This unusual creature is a batfish walking on its enlarged pectoral fins.  It acts so casually because it thinks it’s camouflaged, which it probably is, or perhaps defended in some other way that we can’t see." - Turneffe Island, Belize 2000. Video courtesy Andy Stockbridge, Belize

NOTE shortnose batfish Ogcocephalus nasutus

 
 

Batfishes are a kind of ambush predators and, for whatever reason, they walk about on their pectoral and pelvic fins. Batfishes are related to anglerfishes and, like other members of the group, have a fishing rod and lure for attracting prey ambush-style. When not in use this equipment is tucked beneath the rostrum (snout) at the front of the body. Batfishes mostly feed on small bottom-dwelling invertebrates such as snails, crustaceans, polychaete worms, and also small fishes that they gulp in by rapid inhalation. Obviously, the rod and and its wiggling lure would be useful only with image-forming prey such as fishes and crustaceans. Photograph on Left photograph of batfish Ogcocephalus nasutus displaying rod and lure for use in capturing preycourtesy Anne Dupont, Florida.photograph of pancake batfish Halieuthichthys aculeatus courtesy Anne Dupont, Florida

Face-on view of pancake batfish Halieutichthys
aculeatus
1X. Note the
textural camouflage
on both species

 

View of head of short-nose batfish Ogcocephalus nasutus
with rod and lure extended below the rostrum. The eyes are located below the whiteish "eyebrows" on either side
of the head

 
 

photograph of longlure frogfish
Frogfishes are ambush predators, usually well camouflaged, and also employ a lure to attract prey. The lure is a modified spine located on the tip of the snout, and can be rotated outwards to dangle enticingly in front of the mouth. In the eyes of an intended prey it may mimic a small fish, prawn, or worm, and the frogfish can wiggle it in a lifelike manner. Photograph courtesy Anne Dupont, Florida.

 

 

Longlure frogfish Antennarius multiocellatus 1X.
The rod is the faintly yellowish-coloured structure,
extending from an articulation point above the
upper lip and terminating in a whiteish-coloured lure

  A frogfish's gulp requires just 15msec (15 one-thousandths of a second) and is one of the fastest actions recorded for a vertebrate. The images below represent an imaginative slow-motion replay of the event:
   
 
cartoon 1 of a series showing the lightning-fast attack of a frogfish on a goby cartoon 1 of a series showing the lightning-fast attack of a frogfish on a goby cartoon 2 of a series showing the lightning-fast attack of a frogfish on a goby cartoon 3 of a series showing the lightning-fast attack of a frogfish on a goby
 
 
seahorse dive leader for Biology of Caribbean Coral Reefs website photograph of trumpetfish hiding in a gorgonian, taken from a video

"What’s this?  I almost passed you by. If I had been a little fish you could have reached out and sucked me in.  Oh, watch this! When trumpetfishes stand vertically and bow their backs, it means they're ready to strike. Not this time, though. At the end of the strike the mouth quickly expands to suck in small prey fishes." - Little Cayman 2002

NOTE Aulostomus maculatus

 
  How does suction-feeding by ambush predators work? Several bones of the head are involved. The description accompanying the photos/drawins below are for a generalised type of trumpetfish, but is applicable to other suction-feeders. Drawings and description from Wolff 1991 Functional chordate anatomy. DC Heath & Co., Toronto.
 
photo/drawing 1 in a series illustrating high-speed mouth opening in suction-feeding trumpetfish photo/drawing 2 in a series illustrating high-speed mouth opening in suction-feeding trumpetfish photo/drawing 3 in a series illustrating high-speed mouth opening in suction-feeding trumpetfish
photo/drawing 4 in a series illustrating high-speed mouth opening in suction-feeding trumpetfish photo/drawing 5 in a series illustrating high-speed mouth opening in suction-feeding trumpetfish photo/drawing 6 in a series illustrating high-speed mouth opening in suction-feeding trumpetfish
Expansion of the buccal cavity of a suction-feeding fish like a trumpetfish begins with raising the neurocranium or head bone... ...simultaneously, the hyoid and mandible bones are lowered, and the premaxilla bone is pushed out to increase the mouth's gape... ...the maxilla and mandible bones now swing down and out, which pushes the premaxilla bone up and out to its widest gape.
 
  photograph of a trumpetfish with mouth open for high-speed sucking
Note that the mouth of the trumpetfish and of other high-speed suckers in general tend to be circular in shape, thus preventing water from entering at the corners.
 
 
seahorse dive leader for Biology of Caribbean Coral Reefs website photograph of a sargassumfish about to eat a perch, taken from a video

"Here's another suction-feeder, a sargassumfish, and it's looking to eat a little perch. See how slow and intent the predator is...whoops, there goes the perch. Now for a nice belch."

NOTE Histrio histrio

 
 

photograph of scorpionfish Scorpaena plumieri lying in ambush position
Scorpionfishes also ambush their prey from a camouflaged position. In a split-second extension of the mouth, the oral cavity expands up to 14-fold, sucking in the prey.

 

 

 

Spotted scorpionfish Scorpaena plumieri 0.8X

  Examination of the jaw-lever mechanics of 34 species of Caribbean reef fishes shows that ram-suction species like batfishes have lever ratios favouring equal opening and closing speeds, with both actions being of comparable force. Conversely, fishes that grasp, shred, or crush with their jaws, like barracudas and balloonfishes, have lever ratios favouring powerful closing force, but with weak compensatory opening force (like a dog’s jaws). So, if you think you understand the principle, select the jaw below that best exemplifies a ram-suction jaw. Wainwright & Richard 1995 Environ Biol Fish 44: 97. 
 
diagram of lever ratios in the jaw of a crushing-type predatory fish like a barracuda diagram of lever ratios in the jaw of a suction-type predatory fish like a scorpionfish
 


If you chose the jaw on the Right, you are correct. Note that the opening and closing input-lever-lengthson this jaw are about equal, just like on a teeter-totter. Because of this the jaw rocks back and forth on its fulcrum more-or-less equally, and each motion requires about the same expenditure of force, and produces about the same speeds. In contrast, note that the closing input-lever length of the crushing-type jaw (above Left) is almost diagram of opening and closing lever lengths in the jaw of a suction-type predatory fish like a scorpionfishtwice the length of the opening input-lever length. Here, the closing lever mechanics favour force over speed, while the opening lever mechanics favour speed over force. So, just like the jaws of a dog, you should easily be able to hold the jaws of a barracuda closed with minimal force, with just one hand...


Note that these lever-length considerations do not take into account muscle
masses, or muscle types. A suction-type jaw as shown here would be expected
to have approximately equal opening and closing muscle- masses, probably
of a fast-twitch type. In contrast, the closing muscle mass of a barracuda
would be larger than the opening one, and likely of a slow-twitch variety

 
 

sand-diver lizardfish Synodus intermedium
Another camouflaged ambush predator is the sand-diver lizardfish, which lies in wait throughout the day for non-schooling bottom-dwelling fishes, and for octopuses and shrimps. Photograph courtesy Anne Dupont, Florida.

Some facts about the daytime diet and hunting success of a typical Synodus species from the Great Barrier Reef (Caribbean species are likely similar):

Favoured prey: fishes (the Caribbean S. intermedius also eats shrimps and cephalopods)

Number of prey items eaten per day: 1.8

Frequency of attack: once every 35min

Attack success: 11%

Frequency of changing hunting position: every 4min

 

Caribbean sand-diver lizardfish
Syodus intermedius 0.5X

  Other ambush predators operate from burrows. In this sequence an unknown predator, likely a fish in a burrow, captures a juvenile ocean surgeonfish by its right pectoral fin. Over a period of about 5min the little surgeonfish is progressively pulled to its death.
 
photograph 1 in a series showing a juvenile ocean surgeonfish being ambushed and killed by a burrow-dwelling predator photograph 1 in a series showing a juvenile ocean surgeonfish being ambushed and killed by a burrow-dwelling predator photograph 1 in a series showing a juvenile ocean surgeonfish being ambushed and killed by a burrow-dwelling predator photograph 1 in a series showing a juvenile ocean surgeonfish being ambushed and killed by a burrow-dwelling predator photograph 1 in a series showing a juvenile ocean surgeonfish being ambushed and killed by a burrow-dwelling predator
  A juvenile ocean surgeonfish Acanthurus bahianus is captured and pulled to its death by a burrow-inhabiting predatory fish. The last image shows just the tip ofits tail sticking out.
 
 
seahorse dive leader for Biology of Caribbean Coral Reefs website photograph of two bar jacks cruising the reef, taken from a video

"Bar jacks are just the opposite to ambush predators. With their forked tails and long streamlined pectoral fins, they're built for speed...but in the complexity of the reef they look clumsy…like racing cars amongst city traffic.  I wonder what they are doing here?  If they’re trying to hunt I would think they’d have a hard time running down one of the little reef fishes, who can turn on a dime and disappear in a flash. " - Little Cayman 2002

NOTE Caranx latus

 
 

photograph of horse-eye jack
Studies in Hawai'i show that jacks can increase their hunting success from 2% when attacking spawning fishes in open water, to 17% when attacking the same fishes from ambush positions in the reef. In their ambush positions the jacks become darker in colour and chase other intruding jacks from their "territories". This kind of behaviour may not be typical for all jacks, but it does emphasise their versatility as piscivores. Sancho 2000 Bull Mar Sci 66: 487.




Caribbean horse-eye jack Caranx latus 0.15X

 
number 1 in a series showing attack strategies of horse-eye jacks Caranx latus on spawning fishes number 2 in a series showing attack strategies of horse-eye jacks Caranx latus on spawning fishes number 3 in a series showing attack strategies of horse-eye jacks Caranx latus on spawning fishes
An attack by a jack in open water... ...leads to easy escape by the prey fishes... ...better success is attained from a hidden position...
 

photograph of bar jack Caranx latus hunting with a southern stingray Dasyatis americana
Bar jacks are usually become quite dark when hunting together with southern stingrays. This seems a mis-applied strategy as they would seem to be less contrastingly camouflaged were they to remain lighter in colour.

 

 

 

Typical colour of a bar jack Caranx latus when hunting
with its "host" stingray Dasyatis americana 0.1X

 
 

photograph of green moray Gymnothorax funebrisphotograph of spotted moray Gymnothorax moringa
Moray eels like to eat fishes, and have 3 ways of handling the prey, depending upon size.

 

Green moray Gymnothorax
funebris
0.5X

 

 

Spotted moray Gymnothorax
moringa
0.5X

 
The 3 ways are: 1. SUCTION: rapid opening of the mouth to take in small prey.
2. SHAKE: shaking to tear off bite-sized pieces from larger-sized prey.
3. SPIN: spinning of the body to dismember or tear apart the largest-sized prey.
 

Now, think about the costs involved in each type of feeding and select the method potentially requiring least cost. If your answer is SUCTION-feeding, then you have an inherant understanding of the Optimal Foraging Theory in ecology, which predicts that food choice in animals is governed by benefit versus cost; in this case, what the moray gets in return for energy expended and risks taken. Size of prey is also involved. Of the 3 feeding modes, SUCTION-feeding is least energy-costly, is quickest, involves least risk, and is used for small prey. Next in order is SHAKE-feeding, used on larger prey, and last is SPIN-feeding, used for removing chunks from the largest prey.

NOTE includes time and energy expended, balanced against risk of exposure to its own predators

 
 

pie diagram illustrating dietary components of mutton snappers in Columbia
Most piscivorous fishes have broad-spectrum diets that include many other animal taxa in addition to a primary diet of fishes. For example, the accompanying pie-chart shows prey preferences of mutton snappers photograph of mutton snapper in Columbia. In all, prey from 106 animal taxa are eaten by these Columbian mutton snappers. Duarte & Garcia 1999 Bull Mar Sci 65: 453. Photograph courtesy sammysseafood.com.

 

 

Mutton snapper Lutjanus
analis
0.1X

 
 
seahorse dive leader for Biology of Caribbean Coral Reefs website photograph of bottlenose dolphins taken from a video

"Here's a group of bottlenose dolphins. Their main dietary item is fishes, which they locate and possibly also identify by echolocation." - Turneffe Island, Belize 2000. Video courtesy Andy Stockbridge, Belize.

NOTE Tursiops truncatus

 
 

histogram showing major prey items consumed by bottlenosed dolphins Tursiops truncatus in the Mediterranean Sea
Analyses of stomach contents of 16 stranded bottlenose dolphins Tursiops truncatus in the Mediterranean Sea show that fishes are the dominant prey, along with some cephalopods and crustaceans (see histogram). In all, more than 20 different prey species are eaten, about half of which are fishes. Most of the prey fishes and cephalopods live on or near the sea bottom. Blanco et al. 2001 J Mar Biol Ass UK 81: 1053.

NOTE the same species as found in the Caribbean Sea

 
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