The hardhead catfish (''Ariopsis felis'') is a species of

sea catfish The Ariidae or ariid catfish are a family of catfish that mainly live in marine waters with many freshwater and brackish water species. They are found worldwide in tropical to warm temperate zones. The family includes about 143 species. Taxon ...

from the northwest Atlantic and

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United S ...

, and similar to the

gafftopsail catfish The gafftopsail catfish (''Bagre marinus'') is found in the waters of the western central Atlantic Ocean, as well as the Gulf of Mexico and the Caribbean Sea. It has long, venomous spines which can cause painful wounds. It feeds on crustaceans an ...

(''Bagre marinus''). It is one of four species in the genus '' Ariopsis''. The common name, hardhead catfish, is derived from the presence of a hard, bony plate extending rearward toward the

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through c ...

from a line between the catfish's eyes.Webster, Pearse. Hardhead Catfish. South Carolina Department of Natural Resources. http://www.dnr.sc.gov/cwcs/pdf/Hardheadcatfish.pdf It is an elongated marine catfish that reaches up to in length and in weight. Their typical weight is less than , but they commonly reach up to . They are often a dirty gray color on top, with white undersides.

Habits, distribution, and characteristics

Hardhead catfish are found mostly in the near-shore waters of the

Western Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Africa, Europe and ...

, around the southeast coast of the United States, around the

Florida Keys The Florida Keys are a coral island, coral cay archipelago located off the southern coast of Florida, forming the southernmost part of the continental United States. They begin at the southeastern coast of the Florida peninsula, about south of ...

and the coast of the

. Hardhead catfish are also found in

brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environme ...

and river mouths where the bottom is sandy or muddy, but only occasionally enter freshwater. It tends to move from shallower to deeper waters in the winter months. The species is generally common to abundant within its range. The hardhead catfish has four

barbels In fish anatomy and turtle anatomy, a barbel is a slender, whiskerlike sensory organ near the mouth. Fish that have barbels include the catfish, the carp, the goatfish, the hagfish, the sturgeon, the zebrafish, the black dragonfish and s ...

under the chin, with two more at the corners of the mouth. These barbels help the catfish find crabs, fish, and shrimp in the muddy bays where they live. The dorsal and

pectoral fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

s each are supported by a sharp, slime-covered, barbed spine. The dorsal spine is normally erect when the fish is excited and a tennis shoe or even a leather-soled shoe offers little protection. The

looks similar to the hardhead catfish, but its dorsal and pectoral spines have a distinctive fleshy extension (like the fore-and-aft topsail of a ship).

Feeding behavior

''A. felis'' consumes a wide range of food. It is an opportunistic consumer that uses mud and sand flats as hunting grounds. It is also mainly a

secondary consumer A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other sof ...

, ingesting primarily

detritus In biology, detritus () is dead particulate organic material, as distinguished from dissolved organic material. Detritus typically includes the bodies or fragments of bodies of dead organisms, and fecal material. Detritus typically hosts commu ...

, meio-, and macrobenthic

fauna Fauna is all of the animal life present in a particular region or time. The corresponding term for plants is ''flora'', and for fungi, it is '' funga''. Flora, fauna, funga and other forms of life are collectively referred to as ''biota''. Zoo ...

, and fish. Its diet primarily consists of

algae Algae ( , ; : alga ) are any of a large and diverse group of photosynthetic, eukaryotic organisms. The name is an informal term for a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from ...

, seagrasses,

cnidarians Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, predominantly the latter. Their distinguishing feature is cnidocytes, specialized cells that the ...

sea cucumbers Sea cucumbers are echinoderms from the class Holothuroidea (). They are marine animals with a leathery skin and an elongated body containing a single, branched gonad. Sea cucumbers are found on the sea floor worldwide. The number of holothuri ...

gastropods The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. ...

polychaetes Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are ...

, shrimp, and crabs. It can occasionally be a

tertiary consumer The trophic level of an organism is the position it occupies in a food web. A food chain is a succession of organisms that eat other organisms and may, in turn, be eaten themselves. The trophic level of an organism is the number of steps it i ...

. Its diet depends on its size and location. Younger hardhead catfish tend to eat small

crustaceans Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean gr ...

, like

amphipods Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far descri ...

, shrimp,

blue crabs Blue crab may refer to: * Blue Crab 11, an American sailboat design * ''Callinectes sapidus'' – Chesapeake or Atlantic blue crab of the West Atlantic, introduced elsewhere * '' Cardisoma guanhumi'' – blue land crab of the West Atlantic * ''Disco ...

mollusks Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

, and

annelids The annelids (Annelida , from Latin ', "little ring"), also known as the segmented worms, are a large phylum, with over 22,000 extant species including ragworms, earthworms, and leeches. The species exist in and have adapted to various ecolo ...

. Juveniles that are still under the protection of the male

mouthbrooder Mouthbrooding, also known as oral incubation and buccal incubation, is the care given by some groups of animals to their offspring by holding them in the mouth of the parent for extended periods of time. Although mouthbrooding is performed by a va ...

feed predominately on

planktonic Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a cruc ...

crustaceans close by to the mouth of the parent. The adults primarily consume larger fish.

Locomotion

Significant evidence suggests correlation between the fish's activity patterns and seasonal changes. Under controlled conditions of

photoperiod Photoperiodism is the physiological reaction of organisms to the length of night or a dark period. It occurs in plants and animals. Plant photoperiodism can also be defined as the developmental responses of plants to the relative lengths of light a ...

, temperature, and water quality, hardhead catfish display nonrandom oscillations in angular orientation of locomotive activity. There appears to be annual, bimodal cycles for all three of these variables. The cycles match with the seasonal inshore-offshore migrations of hardhead catfish. Photoperiod appears to be the

exogenous In a variety of contexts, exogeny or exogeneity () is the fact of an action or object originating externally. It contrasts with endogeneity or endogeny, the fact of being influenced within a system. Economics In an economic model, an exogen ...

cue that triggers the cyclic changes in behavior. The presence of this seasonal behavior indicates that a circadian neural mechanism may exist in hardhead catfish.

Communication

Chemical

Hardhead catfish respond to chemicals released by injured individuals with increased activity, illustrating communication among catfish. Their activity level was highest right after the onset of the chemical stimulus. They also respond to chemical cues from injured

sailfin mollies The sailfin molly (''Poecilia latipinna'') is a species of fish of the genus '' Poecilia''. They inhabit fresh, brackish, salt, and coastal waters from North Carolina to Texas and the Yucatán Peninsula of Mexico. Taxonomy The sailfin mo ...

, but this response was weaker than that of the response from their own species. After examining the

epidermis The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and Subcutaneous tissue, hypodermis. The epidermis layer provides a barrier to infection from environmental pathogens and regulates the ...

of the hardhead catfish, the alarm substance cells apparently were similar to those of freshwater catfish. These chemical responses had only been seen in freshwater ostariophysans. Hardhead catfish are the first marine ostariophysans found to elicit this type of alarm reaction.

Echolocation

Furthermore, hardhead catfish are the first indicator that

Osteichthyes Osteichthyes (), popularly referred to as the bony fish, is a diverse superclass of fish that have skeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes, which have skeletons primarily composed of cartila ...

possibly could use directional hearing to detect obstacles. Emissions of low-frequency sounds were related to the detection and avoidance of close obstacles. Individuals within the group that produced sound avoided obstacles, whereas silent individuals crashed into obstacles frequently. Many fish have been associated with sound production for alarm, territorial, and courtship purposes, but sound probing of surroundings seems to be only be seen in hardhead catfish. So far, no evidence exists for far-field echolocation, such as seen in bats or toothed whales. The signal parameters have low frequency and amplitude, so far-field reverberations are unlikely to be useful. If echolocation exists, it is likely only useful in the near field by the catfish.

Sound production

Some evidence indicates sound production in hardhead catfish is differentiated both mechanistically and contextually. Mechanistically, sound can be produced in different ways. Thin bones by the

swim bladder The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled organ that contributes to the ability of many bony fish (but not cartilaginous fish) to control their buoyancy, and thus to stay at their current water depth w ...

can be vibrated by specialized sonic muscles. Also, grinding of the pharyngeal teeth and rubbing of the pectoral spines against the pectoral girdle can produce sound. These two mechanisms appear to be evolved fright responses by the hardhead catfish. Some argue that hardhead catfish use an unrefined form of sonar as a means of echolocation, which also implies some directional hearing ability. It is possible, but is so far unproven, that sound is used in

courtship Courtship is the period wherein some couples get to know each other prior to a possible marriage. Courtship traditionally may begin after a betrothal and may conclude with the celebration of marriage. A courtship may be an informal and private ...

and

spawning Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aqua ...

Lifecycle and reproduction

The hardhead catfish has a reproductive season from around May to September. Males and females reach sexual maturity before age 2. Females at maturity are around , and males typically are slightly larger, around . At maturity, females develop flap-like fatty tissue by their pelvic fins, which results in them having larger pelvic fins than males. These enhanced pelvic fins may be the site of fertilization and play a part in moving the fertilized eggs to the male mouthbrooder for incubation. Another possibility is that males pick up eggs from depressions in the sand, as eggs tend to be

demersal The demersal zone is the part of the sea or ocean (or deep lake) consisting of the part of the water column near to (and significantly affected by) the seabed and the benthos. The demersal zone is just above the benthic zone and forms a laye ...

. They also die after 4 years.

Parental care

Mouthbrooding

Like other members of the

Ariidae The Ariidae or ariid catfish are a family of catfish that mainly live in marine waters with many freshwater and brackish water species. They are found worldwide in tropical to warm temperate zones. The family includes about 143 species. Taxonom ...

, hardhead catfish are paternal mouthbrooders. After spawning, the male carries the eggs in his mouth until they hatch. Several nonfunctioning eggs within the brood attach to the larger, viable eggs. These nonfunctioning eggs may be used as food for the male mouthbrooder, since mouthbrooders do not feed while they are taking care of the brood. Oral incubations continue through the yolk-sac larval state, for a total length around 8–11 weeks. Under laboratory conditions, offspring can hatch in roughly 30 days. The offspring are roughly 6–8 cm long and slowly adapt to adult behavior, such as opportunistic bottom-feeding and scavenging. At absorption of the yolk sac, juveniles begin to show adult characteristics. The parental male can choose to carry the young after they have hatched until they are larger and capable of surviving on their own.

Advantages

Many advantages to mouthbrooding exist as opposed to other forms of parental care, such as

bubble nest Bubble nests, also called foam nests, are created by some fish and frog species as floating masses of bubbles blown with an oral secretion, saliva bubbles, and occasionally aquatic plants. Fish that build and guard bubble nests are known as aphr ...

ing. Mouthbrooders are able to freely move with the eggs in their mouths, thus can move as necessary to protect both themselves and the broods. Though mouthbrooding requires more energy by the male, the chance of his young surviving to adulthood is greater, thus reproducing and continuing his genes; the eggs are not defenseless while in their father's mouth. Mouthbrooding by males counters the relatively low

fecundity Fecundity is defined in two ways; in human demography, it is the potential for reproduction of a recorded population as opposed to a sole organism, while in population biology, it is considered similar to fertility, the natural capability to pr ...

of females, which only have 20-65 eggs per spawning episode. Finally, through breathing, the male is able to keep the brood well oxygenated, which also increases brood survival.

Fishing

Hardhead catfish are voracious feeders and will bite on almost any natural bait. Hardhead catfish are also known to steal bait. Shrimp is a particularly effective bait to use. When fishing for this species in fresh water, assorted meats tend to work best as bait. For example: bacon, chicken, cuts of steak, and smaller fish. Hardhead catfish are generally regarded as an undesirable catch by most anglers, largely due to the risk associated with handling the venomous fish, as well as its 'fishy' taste as opposed to desirable game fish. Hardhead catfish are edible, but like all catfish, require some effort to clean. It is one of the 30 most recreationally harvested species in the five-county area (Volusia, Brevard, Indian River, St. Lucie, Martin) encompassing the

Indian River Lagoon The Indian River Lagoon is a grouping of three lagoons: the Mosquito Lagoon, the Banana River, and the Indian River, on the Atlantic Coast of Florida; one of the most biodiverse estuaries in the Northern Hemisphere and is home to more than 4,3 ...

in central Florida. From 1997 to 2001, 361,022 hardhead catfish were harvested within 200 miles of the shore in the IRL region. Hardheads are also harvested for industrial purposes in commercial bottom-trawling operations. Annual harvests vary greatly, but from 1987 to 2001, 1.04 million pounds of marine catfishes (including both the hardhead catfish and the gafftopsail catfish) were harvested in the IRL region. The harvest was valued at $777,497.

Weight and length

Hardhead catfish weigh around and measure long. As hardhead catfish grow longer, they increase in weight. The relationship between length and weight is not linear. The relationship between total length (L, in inches) and total weight (W, in pounds) for nearly all species of fish can be expressed by an equation of the form: :

W = cL^b\!\,

Invariably, b is close to 3.0 for all species, and c is a constant that varies among species. The relationship described in this section suggests that a hardhead catfish will weigh about , while a hardhead catfish will likely weigh at least .

References

External links

Smithsonian Marine Station at Fort Pierce
{{Taxonbar, from=Q513555

hardhead catfish The hardhead catfish (''Ariopsis felis'') is a species of sea catfish from the northwest Atlantic and Gulf of Mexico, and similar to the gafftopsail catfish (''Bagre marinus''). It is one of four species in the genus '' Ariopsis''. The common nam ...

Fish of the Western Atlantic Fish of the Eastern United States Fish of the Gulf of Mexico Fauna of the Southeastern United States Commercial fish Sport fish

Taxa named by Carl Linnaeus