I have heard these fishes described as being so ugly that their looks are endearing, so ugly that they are cute. Grotesque, frumpy, grumpy, defiant and alien looking are some other words used to describe these fishes, a group that includes a variety of species known as frogfishes, toadfishes, scorpionfishes and stonefishes.
While these fishes share the characteristic of having faces that can make you recoil, taxonomic specialists describe them in different families. In this article we’ll examine the natural history of a variety of Neptune’s less attractive, but commonly encountered, fishes to help you recognize who is who on what some would call the all-ugly team of fishes.
Worldwide there are 41 known species of frogfishes. Described in 12 genera, all are members of the family Antennariidae. These species are widely distributed in tropical and subtropical seas around the world. Frogfishes are benthic, or bottom-dwelling, creatures that inhabit depths ranging from only a few meters to the deep sea.
In general terms, frogfishes are small, stocky fishes that have loose, prickly looking skin; limblike pectoral fins with an elbowlike joint; small, round gill openings; and rather large mouths that are directed upward.
Frogfishes are part of a group of several fish families that are collectively known by the common name anglerfishes. Masters of the arts of camouflage and mimicry, frogfishes are superbly suited for their lives as ambush predators. As is the case with many other anglerfishes, frogfishes disguise themselves to blend with their surroundings, but they don’t just wait around for their favorite prey, a combination of small fishes and crustaceans, to randomly enter into their strike zone. Instead, they attempt to lure their prey within striking distance.
Near the front of the head just above the eyes, the first dorsal spine in frogfishes has been modified over time into a movable, fishing rodlike appendage known as the illicium that is tipped with a lure called the esca. The “rod” comes in different lengths and is sometimes striped, while the esca is usually shaped like a shrimp or small fish. When hunting, frogfishes extend the illicium and wiggle the esca as they try to lure their prey within striking distance.
In a phenomenon known as bioluminescence, the frogfishes that inhabit the deep sea possess an esca that glows because of symbiotic algae that lives in the tissue of the lure. These species are armed with an enormous mouth that is packed with large, needlelike teeth. Some deep-water frogfishes have other appendages on their chin that display bioluminescence to help them attract their prey.
While frogfishes are not fast swimmers by any stretch of the imagination, they are quite capable of making quick lunges that are fast enough to catch their desired prey of small fishes.
But their fishing technique and fast lunges by these otherwise slow-moving fishes are not the only weapons in their arsenal. Not by a long shot. When feeding, a frogfish rapidly opens its mouth and expands its oral cavity in a “gape and suck” action that enables the hunters to engulf their prey and suck it down whole. Frogfishes accomplish this feat by opening their mouth and oral cavity so fast that it creates a powerful suction, and they have split-second control over the timing. Specialists tell us this “gape and suck” action is the fastest feeding mechanism known in the world of fishes, requiring only 0.006 seconds, and it is reported that frogfishes routinely take one member of a group of schooling fish out of a school without the other fish even noticing.
The opening and closing of the gill covers also help to create the suction. Interestingly, if a frogfish loses its lure in the process of catching its food it is capable of growing a new one, but this process takes a long time.
Compared with most fishes, frogfishes are rather pathetic swimmers. They lack a swim bladder and usually move by “walking” on their fins rather than swimming. However, at times they do swim to get from place to place. Although they can use the side-to-side movement of their tail to push them ever so slowly through the water, they are likely to also use jets of water that they force through their reduced gill openings to propel them along their way in a jet-propulsion method that looks somewhat comical.
As a rule, frogfishes sit motionless on the substrate, usually on the sea floor but sometimes on a sponge or other organism or structure that they mimic as they attempt to blend with their surroundings. If you spot a frogfish and you avoid sudden movements and don’t charge right in, you will probably have an excellent opportunity to get a very close look. However, once they become aware that their presence is known, frogfishes often turn and face away from intruders.
Finding a frogfish on your own can be a challenge. In fact, the first time or two that someone tries to point one out to you underwater, you might have a difficult time recognizing the fish even from close range. Their lack of motion combined with their shape, coloration and the texture of their skin makes them amazingly inconspicuous. However, once discovered, frogfishes can often be found for days, and even months, on end resting in almost the exact place in the same position. If you discover a frogfish and return to the dive site a few days later, but do not find the fish, be patient. Stop and look around, and often you will be able to find the fish only a few feet from where it was on your previous dive.
Given their common name because they often croak like a frog by vibrating their swim bladder when distressed, toadfishes are another member of this group of unusual looking fishes that are often described as just plain ol’ ugly. Occurring in the Atlantic, Indian and Pacific oceans, toadfishes include 69 species in 19 genera. All are members of the family Batrachoididae.
Toadfishes are bottom-dwelling creatures that resemble few other fishes. Their heads are greatly flattened, and their wide mouths appear to be far too large for the length of their bodies. Most specimens are less than 12 inches (30 cm) long. A “beard” of chemosensory barbells is prominent on the chins of many individuals, and in many instances the teeth are exposed when a toadfish is at rest on the sea floor.
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Rather sluggish in their movements, toadfishes often hide in recesses in the reef during the day, and at night they lie-in-wait near the openings of small crevices and in depressions under coral ledges hoping to ambush a variety of crustaceans and mollusks that wander by.
Various species of toadfishes can be found from shallow inshore waters to the deep sea. Several species routinely migrate between shallow and deep waters, and some species routinely enter rivers.
Described in the subfamily Thalassophryninae, a number of toadfishes are known to be venomous. They are armed with hollow spines in their first dorsal fin and on their gill covers. These spines are connected to venom glands that can force poison into a puncture wound.
The family Scorpaenidae contains 23 genera of fishes known as scorpionfishes as well as the species known as sculpins, lionfishes, turkeyfish, waspfishes, redfishes, flatheads, devilfishes and more.
A unifying characteristic of all of these fishes is the possession of venomous stinging spines. Some species such as lionfishes and turkeyfish are considered extraordinarily attractive creatures by many people. Others, such as the waspfishes, are rarely encountered. However, many people insist that a number of commonly encountered species known as scorpionfishes and sculpins easily qualify for Mother Nature’s All-Ugly Team.
Scorpionfishes occur primarily in shallow waters in tropical and subtropical seas; however, there is at least one oceanic species that prefers mid-water and a number of species known as idiotfishes inhabit areas as deep as 7,000 feet (2,121 m). The species of sculpins and scorpionfishes that are typically encountered by sport divers are bottom dwellers that are less than 12 inches (30 cm) long. Masters of camouflage with appearances that vary greatly, these fishes are ambush predators that chiefly prey upon a variety of crustaceans and other fishes. Many specimens sport patches of algae that cover large parts of their bodies, and some possess fleshy, branched appendages that help them blend into their surroundings. The scorpionfishes found in the Atlantic and Caribbean are often mistakenly referred to as a stonefish, but members of the far more venomous stonefish family occur only in the Indo-Pacific.
As is the case with other ambush predators, sculpins and scorpionfishes spend a lot of time sitting still on the sea floor either resting or waiting for unsuspecting prey to come along. Because they do such a great job of mimicking their surroundings, these fishes can be quite difficult to spot, but their possible presence is a good reason to always look closely before settling onto the sea floor or reaching out to balance with a hand. You definitely want to avoid contact with a sculpin or scorpionfish as they can inflict a painful sting. While not usually as serious as the injury caused by the venom of a stonefish, the puncture wound and injection of venom from a sculpin or scorpionfish is guaranteed to be very unpleasant — rivaling the sting of a bee or wasp. Medical attention might be required.
All four species of stonefishes are members of the family Synanceiidae. With two species being widespread throughout the tropical Indo-Pacific and typically inhabiting silty or rubble-strewn bottoms in protected, shallow areas, and the other two species (also Indo-Pacific) being much rarer, the stonefishes are believed to be the world’s most venomous fishes. The venom inflicted by the stings of their hollow dorsal spines can create excruciating pain, and in some instances, envenomization has been fatal to humans. The venom is contained in 26 specialized glands below the skin along the back. Ducts that lead away from these glands connect to 13 sharp, dorsal spines (two venom sacs per spine) that are enclosed in fleshy sheaths.
When a stonefish is relaxed and not feeling threatened, the spines are folded downward along the back, but at the slightest disturbance the spines can be quickly raised to protrude from their sheaths. Interestingly, the potent venom is only used in defense, and not for capturing prey.
While it is easy to admire their ability to blend into their surroundings, it is difficult to find a better phrase than indisputably ugly to describe stonefishes. These bottom dwellers have irregular-shaped bodies that are usually a blotchy reddish-brown color. Further enhancing their camouflage capability is the secretion of a sticky fluid from wartlike growths on their skin that causes various algae, mud, coral rubble and other debris to stick to their body, and it is quite common for a variety of small invertebrates such as anemones and hydroids to colonize these fishes. The whole package makes stonefishes very difficult to find. However, once seen, the hideous, “don’t tread on me” appearance is likely to make a lasting impression.
A closer inspection reveals a relatively large, bulbous head, a pair of well-camouflaged eyes that sit high atop the head, and a rather large, upturned mouth that is perfectly positioned for an ambush predator that rests on the sea floor while waiting to victimize fishes and crustaceans. The body tapers to what appears to be a relatively small tail.
Even when you are absolutely certain that a stonefish sees you, they are still quite reluctant to move. As a result, these fishes are relatively easy animals to photograph once the challenge of finding a stonefish has been met. But you will want to be careful not to touch, poke or prod, as their sting is no laughing matter.
Spotting a frogfish, toadfish, scorpionfish and stonefish is guaranteed to make a dive memorable, and as you look at these wonders of nature my bet is that you, too, will find these bizarre-looking fishes to be so ugly that to your eyes, like perhaps those of their mothers, they are cute.
It’s Not Their Looks That Can Kill
A sting from a stonefish, scorpionfish and some toadfishes is a serious matter. In some cases, depending upon the severity of the sting, location on the victim’s body, the amount of venom delivered, and the way an individual reacts to a particular venom, a sting can prove fatal. At the very least, the venom from a sting leads to severe pain. Profound muscle weakness, uncontrollable muscle spasms, nausea and vomiting often result. Obviously, if stung, the victim should immediately surface and leave the water.
Medical attention is recommended to monitor the victim’s condition and to determine whether pieces of the spines remain imbedded in the injured area. Removal of the spines is necessary to prevent infection. Immersing the wound in hot water is recommended in an effort to break down the toxins, but the water should not be hot enough to cause skin damage.