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93-463: Herrington Lake contains many species of fish, including bluegill , catfish , crappie , hybrid striped bass , largemouth bass , spotted bass , and white bass . Dix Dam , the dam that made the lake, was the largest earth-filled dam in the world at the time, and considered to be a major engineering feat. Kentucky Utilities' main dispatch and communication center is located on the site. This Boyle County, Kentucky state location article

186-409: A lower jaw and can bear numerous ordered teeth . Cartilaginous fishes grow multiple sets (polyphyodont) and replace teeth as they wear by moving new teeth laterally from the medial jaw surface in a conveyor-belt fashion. Teeth are replaced multiple times also in most bony fishes, but unlike cartilaginous fishes, the new tooth erupts only after the old one has fallen out. Jaws probably originated in

279-452: A negative pressure in the mouth. Instead, when the moray bites prey, it first bites normally with its oral jaws, capturing the prey. Immediately thereafter, the pharyngeal jaws are brought forward and bite down on the prey to grip it; they then retract, pulling the prey down the moray eel's gullet, allowing it to be swallowed. All vertebrates have a pharynx, used in both feeding and respiration. The pharynx arises during development through

372-401: A terminal mouth , ctenoid scales, and a lateral line that is arched upward anteriorly. The bluegill typically ranges in size from about 4 to 12 inches (100–300 mm), and reaches a maximum size just over 16 inches (410 mm). The largest bluegill ever caught was 4 lb 12 oz (2.2 kg) in 1950. The bluegill is most closely related to the orangespotted sunfish and

465-411: A balance between food abundance and predator abundance. Bluegill use gill rakers and bands of small teeth to ingest their food. During summer months, bluegills generally consume 3.2 percent of their body weight each day. To capture prey, bluegills use a suction system in which they accelerate water into their mouth. Prey comes in with this water. Only a limited amount of water is able to be suctioned, so

558-410: A command center for the escape response and respond quickly once the neural pathway has been activated by an initial stimulus. The cells trigger a contraction of muscle that bends the fish body into a 'C' to then aid in the propulsion away from a predator. The C-start trajectory is highly variable, allowing the fish to alter its escape response each time. Because of this high variability, predators have

651-456: A few changes to the form of cranial bones, allow it to achieve extreme jaw protrusion. Pharyngeal jaws are a second set of jaws distinct from the primary (oral) jaws. They are contained within the throat, or pharynx , of most bony fish . They are believed to have originated, in a similar way to oral jaws, as a modification of the fifth gill arch which no longer has a respiratory function. The first four arches still function as gills. Unlike

744-567: A high speed of jaw opening, opening their jaws in 20 milliseconds and completing the whole process in 50-60 milliseconds, comparable to modern fishes that use suction feeding to assist in prey capture. They could also produce high bite forces when closing the jaw, estimated at 6,000 N (1,350 lb f ) at the tip and 7,400 N (1,660 lb f ) at the blade edge in the largest individuals. The pressures generated in those regions were high enough to puncture or cut through cuticle or dermal armour suggesting that Dunkleosteus terrelli

837-431: A key role within the food chain of its freshwater ecosystem . A popular panfish among anglers , bluegill usually hide around and inside old tree stumps in swamps and other underwater structures (e.g. snags ), and can live in either deep or very shallow water. Bluegills also like to find shelter among aquatic plants and in the shade of trees along banks , and will often move from one cover to another depending on

930-413: A large great white shark may have up to five layers. In the rostrum (snout), the cartilage can be spongy and flexible to absorb the power of impacts. In sharks and other extant elasmobranchs the upper jaw is not fused to the cranium , and the lower jaw is articulated with the upper. The arrangement of soft tissue and any additional articulations connecting these elements is collectively known as

1023-447: A layer of tiny hexagonal plates called " tesserae ", which are crystal blocks of calcium salts arranged as a mosaic . This gives these areas much of the same strength found in the bony tissue found in other animals. Generally sharks have only one layer of tesserae, but the jaws of large specimens, such as the bull shark , tiger shark , and the great white shark , have two to three layers or more, depending on body size. The jaws of

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1116-404: A lower chance of learning a successful predation technique to capture the fish. The C-start escape response produces other advantages, including the ability to move quickly and unpredictably to capture prey. Hydrodynamically, the bluegill exhibits specific flow patterns that accompany its C-start escape response. The caudal (tail) fin is a main source of momentum in typical kinematic models of

1209-481: A primary study species in fish-feeding biomechanics due to their jaw structure. They have protractile mouths, usually with separate jaw teeth that jut outwards. Many species can be readily recognized by their thick lips, the inside of which is sometimes curiously folded, a peculiarity which gave rise the German name of "lip-fishes" ( Lippfische ). The nasal and mandibular bones are connected at their posterior ends to

1302-504: A secondary function before becoming the primary function in many vertebrates. All vertebrate jaws, including the human jaw, evolved from early fish jaws. The appearance of the early vertebrate jaw has been described as "perhaps the most profound and radical evolutionary step in the vertebrate history". Fish without jaws had more difficulty surviving than fish with jaws, and most jawless fish became extinct. Jaws use linkage mechanisms . These linkages can be especially common and complex in

1395-444: A series of loosely connected bones. Lampreys and sharks only possess a cartilaginous endocranium, with both the upper and lower jaws being separate elements. Bony fishes have additional dermal bone , forming a more or less coherent skull roof in lungfish and holost fish. The simpler structure is found in jawless fish , in which the cranium is represented by a trough-like basket of cartilaginous elements only partially enclosing

1488-463: A series of six or more outpocketings called pharyngeal arches on the lateral sides of the head. The pharyngeal arches give rise to a number of different structures in the skeletal, muscular and circulatory systems in a manner which varies across the vertebrates. Pharyngeal arches trace back through chordates to basal deuterostomes who also share endodermal outpocketings of the pharyngeal apparatus. Similar patterns of gene expression can be detected in

1581-458: A single bluegill population may eat up to six times its own weight in just one summer. However, certain species of bluegill can become overpopulated and overrun a pond's ecosystem if not managed properly. Pond owners typically control the bluegill population by handfishing and trapping of the fish to control population size. Fish jaw Most bony fishes have two sets of jaws made mainly of bone . The primary oral jaws open and close

1674-558: A time as opposed to the simultaneous replacement of an entire row. However, in piranhas and pacus , all the teeth on one side of the jaw are replaced at a time. Tooth shape depends on the shark's diet: those that feed on mollusks and crustaceans have dense and flattened teeth used for crushing, those that feed on fish have needle-like teeth for gripping, and those that feed on larger prey such as mammals have pointed lower teeth for gripping and triangular upper teeth with serrated edges for cutting. The teeth of plankton-feeders such as

1767-483: A very distinctive coloring, with deep blue and purple on the face and gill cover, dark olive-colored bands down the side, and a fiery orange to yellow belly. They are omnivorous and will consume anything they can fit in their mouth, but mostly feed on small aquatic insects and baitfishes . The fish are important prey for bass , other larger sunfish , northern pike and muskellunge , walleye , trout , herons , kingfishers , snapping turtles and otters , and play

1860-444: Is a stub . You can help Misplaced Pages by expanding it . This Mercer County, Kentucky state location article is a stub . You can help Misplaced Pages by expanding it . This Garrard County, Kentucky state location article is a stub . You can help Misplaced Pages by expanding it . Bluegill Lepomis purpurescens Cope , 1870 The bluegill ( Lepomis macrochirus ), sometimes referred to as "bream", "brim", "sunny", or, as

1953-414: Is a piece of cartilage from which the mandibles (lower jaws) of vertebrates evolved. Originally it was the lower of two cartilages which supported the first gill arch (nearest the front) in early fish. Then it grew longer and stronger, and acquired muscles capable of closing the developing jaw. In early fish and in chondrichthyans (cartilaginous fish such as sharks ), Meckel's cartilage continued to be

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2046-539: Is also occasionally used as bait for larger game fish species, such as blue catfish , flathead catfish and largemouth bass . Fishermen are sometimes able to use polarized sunglasses to see through water and find bluegills' spawning beds. Bluegill have a rather bold character; many have no fear of humans, eating food directly dropped into the water, and a population in Canada 's Lake Scugog will even allow themselves to be stroked by human observers. Because of their size and

2139-687: Is common in Texas , "copper nose", is a species of North American freshwater fish , native to and commonly found in streams, rivers, lakes, ponds and wetlands east of the Rocky Mountains . It is the type species of the genus Lepomis (true sunfish), from the family Centrarchidae (sunfishes, crappies and black basses ) in the order Perciformes ( perch -like fish). Bluegills can grow up to 16 in (41 cm) long and about 4 + 1 ⁄ 2  lb (2.0 kg). While their color can vary from population to population, they typically have

2232-447: Is composed of a cartilaginous structure homologous with the Meckel's cartilage of other groups. This also remains a significant element of the jaw in some primitive bony fish, such as sturgeons . The upper jaw, or maxilla is a fusion of two bones along the palatal fissure that form the upper jaw . This is similar to the mandible (lower jaw), which is also a fusion of two halves at

2325-527: Is not just the reversal of forward swimming. The fish utilizes its pectoral fins to provide a rhythmic beat while the dorsal and anal fins produce momentum to drive the fish backwards. The pectoral fins' rhythmic beat is asymmetric and aids the fish's balance in its slow, backward movement. The bluegill, amongst a wide array of other fishes, exhibits the C-start escape response , which is generated by large neurons called Mauthner cells . Mauthner cells operate as

2418-498: Is regulated by frequency-dependent selection . In cichlids generally, the oral and pharyngeal teeth differ with different species in ways that allow them to process different kinds of prey. Primary oral jaws contain teeth which are used to capture and hold food, while pharyngeal jaws have pharyngeal teeth which function as a chewing tool. This allows for different nutritional strategies, and because of this, cichlids are able to colonize different habitats. The structural diversity of

2511-424: Is scarce, bluegill will also feed on aquatic vegetation and algae , and if scarce enough, will even feed on their own eggs or offspring. As bluegill spend a great deal of time near the surface of water, they can also feed on surface bugs. Most bluegills feed during daylight hours, with a feeding peak being observed in the morning and evening (with the major peak occurring in the evening). Feeding location tends to be

2604-717: Is the state fish of Illinois . At Lake St. Helen , Michigan, an annual "Blue Gill Festival" is held in July. Bluegills are popular panfish , caught with live bait such as worms, crickets, grasshoppers, flies , minnows, maggots or small frogs, as well as small shrimp bits, processed bait, bread, corn, other table scraps, small crankbaits, spinners, fake worms, or even a bare hook. They mostly bite on vibrant colors like orange, yellow, green, or red, chiefly at dawn and dusk. They are noted for seeking out underwater vegetation for cover; their natural diet consists largely of crickets, water bugs, larvae , and very small fish. The bluegill itself

2697-534: Is very rapid in the first three years, but slows considerably once the fish reaches maturity. Many fish reach five to eight years old, and in extreme cases, can live 11 years. Occasionally a bluegill may spawn with another member of its genus, though this is rare. This tends to happen in bodies of water that are fairly isolated and have a decent population of bluegill in close proximity to another, smaller, population of lepomid species such as green sunfish . Limited nesting grounds can also factor in hybridization causing

2790-815: The Chesapeake Bay , indicating they can tolerate up to 1.8% salinity. In some locations where they have been transplanted, they are considered pests: trade in the species is prohibited in Germany and Japan . In the case of Japan, bluegills were presented to the then-crown prince, Akihito , in 1960 as a gift by Richard J. Daley , mayor of Chicago . The prince, in turn, donated the fish to fishery research agencies in Japan, from which they escaped and became an invasive species that wreaked havoc with native species, especially in Lake Biwa . Akihito has since apologized. Bluegill live in

2883-477: The Early Permian about 290 million years ago. The original selective advantage offered by the jaw may not be related to feeding, but rather to increased respiration efficiency. The jaws were used in the buccal pump still observable in modern fish and amphibians , that uses "breathing with the cheeks" to pump water across the gills of fish or air into the lungs in the case of amphibians. Over evolutionary time

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2976-479: The basking shark and whale sharks are very small. Male salmon often remodel their jaws during spawning runs so they have a pronounced curvature. These hooked jaws are called kypes . The purpose of the kype is not altogether clear, though they can be used to establish dominance by clamping them around the base of the tail ( caudal peduncle ) of an opponent. Fish jaws, like vertebrates in general, normally show bilateral symmetry . An exception occurs with

3069-533: The gums rather than directly affixed to the jaw as in some fish. Shark teeth form within the jaw move outward in rows until they are eventually dislodged in a manner similar to a conveyor belt . Their scales, called dermal denticles , and teeth are homologous organs . Some sharks lose 30,000 or more teeth in their lifetime. The rate of tooth replacement varies from once every 8 to 10 days to several months, although few studies have been able to quantify this. In most species of bony fish , teeth are replaced one at

3162-408: The jaw suspension . There are several archetypal jaw suspensions: amphistyly, orbitostyly, hyostyly, and euhyostyly. In amphistyly, the palatoquadrate has a postorbital articulation with the chondrocranium from which ligaments primarily suspend it anteriorly. The hyoid articulates with the mandibular arch posteriorly, but it appears to provide little support to the upper and lower jaws. In orbitostyly,

3255-400: The larvae are able to hatch and swim away on their own. The bluegill generally begins its spawning career at one year of age, but has been found to spawn as early as four months of age under favorable conditions. Anglers find spawning season to be a very successful time to fish for bluegills, as they aggressively attack anything, including a hook, that comes near. The growth of the bluegill

3348-413: The parasitic scale-eating cichlid Perissodus microlepis . The jaws of this fish occur in two distinct morphological forms. One morph has its jaw twisted to the left, allowing it to eat scales more readily on its victim's right flank. The other morph has its jaw twisted to the right, which makes it easier to eat scales on its victim's left flank. The relative abundance of the two morphs in populations

3441-442: The pelican eel , has jaws larger than its body. The jaws are lined with small teeth and are loosely hinged. They open wide enough to swallow a fish larger than the eel itself. Distichodontidae are a family of fresh water fishes which can be divided into genera with protractile upper jaws which are carnivores , and genera with nonprotractile upper jaws which are herbivores or predators of very small organisms. The appearance of

3534-509: The pharyngeal arches supporting the gills of jawless fish . The earliest jaws appeared in now extinct placoderms and spiny sharks during the Silurian , about 430 million years ago. The original selective advantage offered by the jaw was probably not related to feeding, but to increased respiration efficiency—the jaws were used in the buccal pump to pump water across the gills. The familiar use of jaws for feeding would then have developed as

3627-406: The premaxilla , leading to three main four-bar linkage systems to generally describe the lateral and anterior expansion of the buccal cavity in fishes. The most thorough overview of the different types of linkages in animals has been provided by M. Muller, who also designed a new classification system, which is especially well suited for biological systems. The skull of fishes is formed from

3720-614: The redear sunfish , but different in a distinct spot at or near the base of the soft dorsal fin. The bluegill occurs naturally in the United States east of the Rocky Mountains from coastal Virginia to Florida , west to Texas and northern Mexico , and north to western Minnesota , New York and southeastern Ontario . They have been introduced widely in North America and Europe , South Africa , Zimbabwe , Asia , South America , and Oceania . Bluegills have also been found in

3813-416: The rostrum , and capsules to enclose the olfactory organs. Behind these are the orbits, and then an additional pair of capsules enclosing the structure of the inner ear . Finally, the skull tapers towards the rear, where the foramen magnum lies immediately above a single condyle , articulating with the first vertebra . There are, in addition, at various points throughout the cranium, smaller foramina for

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3906-520: The C-start escape response but the bluegill draws a majority of its momentum from the body bending associated with the response, as well as its dorsal and anal fins. The dorsal and anal fins' roles as propulsors during escape response suggest that the size of the fins could lead to an evolutionary advantage when escaping predators. Spawning season for bluegills starts late in May and extends into August. The peak of

3999-426: The angle of the jaw is formed by a lower angular bone and a suprangular bone just above it. The inner surface of the jaw is lined by a prearticular bone, while the articular bone forms the articulation with the skull proper. Finally a set of three narrow coronoid bones lie above the prearticular bone. As the name implies, the majority of the teeth are attached to the dentary, but there are commonly also teeth on

4092-490: The bluegill is deprived of its various sensory abilities, it utilizes its pectoral fins in navigation. If the bluegill's visual input or lateral line input were to be compromised, its pectoral fins are then able to be utilized as mechanosensors through the bending of the fin(s) when the fish comes into contact with its environment. In standard swimming the bluegill sunfish relies on its caudal (tail) fin, dorsal fin, and anal fin. The bluegill's caudal fin muscles are important in

4185-412: The brain, and associated with the capsules for the inner ears and the single nostril. Cartilaginous fish , such as sharks , also have simple skulls. The cranium is a single structure forming a case around the brain, enclosing the lower surface and the sides, but always at least partially open at the top as a large fontanelle . The most anterior part of the cranium includes a forward plate of cartilage,

4278-436: The center of colonies. Populations with large males are increasingly difficult to find, and are usually only found in remote locations without angling pressure or in more southern regions where growth rates are high. Reduced bag limits appear to show potential for improving size-structure in over-fished populations. Bluegills play an important role in pond and lake management to keep crustacean and insect populations low, as

4371-444: The coronoid bones, and sometimes on the prearticular as well. This complex primitive pattern has, however, been simplified to various degrees in the great majority of vertebrates, as bones have either fused or vanished entirely. In teleosts , only the dentary, articular, and angular bones remain. Cartilaginous fish , such as sharks , do not have any of the bones found in the lower jaw of other vertebrates. Instead, their lower jaw

4464-420: The cranial nerves. The jaws consist of separate hoops of cartilage, almost always distinct from the cranium proper. In ray-finned fishes , there has also been considerable modification from the primitive pattern. The roof of the skull is generally well formed, and although the exact relationship of its bones to those of tetrapods is unclear, they are usually given similar names for convenience. Other elements of

4557-708: The cranium. Instead, the hyomandibular cartilages provide the only means of jaw support, while the ceratohyal and basihyal elements articulate with the lower jaw, but are disconnected from the rest of the hyoid. Jaws provide a platform in most bony fish for simple pointed teeth , however, there are many exceptions. Some fish like carp and zebrafish have pharyngeal teeth only. Sea horses , pipefish , and adult sturgeon have no teeth of any type. In fish , Hox gene expression regulates mechanisms for tooth initiation. While both sharks and bony fish continuously produce new teeth throughout their lives, they do so via different mechanism. Shark teeth are embedded in

4650-475: The daylight hours. The mouth of the bluegill is very small and requires the use of the pharynx to suck in prey. The bluegill sunfish relies heavily on the flexibility of its fins to maintain maneuverability in response to fluid forces. The bluegill's segmentation in its pectoral fin rays mitigates the effects of fluid forces on the fish's movement. The bluegill has a variety of unusual adaptations that allow it to navigate different environments. In conditions where

4743-425: The deep remodelling of the vertebrate skull that must have taken place as early jaws evolved. The customary view is that jaws are homologous to the gill arches . In jawless fishes a series of gills opened behind the mouth, and these gills became supported by cartilaginous elements. The first set of these elements surrounded the mouth to form the jaw. The upper portion of the second embryonic arch supporting

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4836-419: The deep sea. Relative to their size they have one of the widest gapes of any fish. The lower jaw has no ethmoid membrane (floor) and is attached only by the hinge and a modified tongue bone. There are several large, fang-like teeth in the front of the jaws, followed by many small barbed teeth. There are several groups of pharyngeal teeth that serve to direct food down the esophagus . Another deep sea fish,

4929-426: The developing pharynx of amphioxus and hemichordates . However, the vertebrate pharynx is unique in that it gives rise to endoskeletal support through the contribution of neural crest cells. Cartilaginous fishes ( sharks , rays and skates ) have cartilaginous jaws. The jaw's surface (in comparison to the vertebrae and gill arches) needs extra strength due to its heavy exposure to physical stress. It has

5022-476: The early vertebrate jaw has been described as "a crucial innovation" and "perhaps the most profound and radical evolutionary step in the vertebrate history". Fish without jaws had more difficulty surviving than fish with jaws, and most jawless fish became extinct during the Triassic period. However studies of the cyclostomes , the jawless hagfishes and lampreys that did survive, have yielded little insight into

5115-441: The edge of the nest. As a female approaches, the male will begin circling and making grunting noises. The motion and sound of the males seem to attract the females. Females are very choosy and will usually pick males with larger bodies and "ears", making larger size a desirable trait for males to have. If the female enters the nest, both the male and female will circle each other, with the male expressing very aggressive behavior toward

5208-450: The end of that period, about 360 million years ago. Their largest species, Dunkleosteus terrelli , measured up to 10 m (33 ft) and weighed 3.6  t (4.0 short tons ). It possessed a four bar linkage mechanism for jaw opening that incorporated connections between the skull, the thoracic shield, the lower jaw and the jaw muscles joined together by movable joints. This mechanism allowed Dunkleosteus terrelli to achieve

5301-403: The female's eggs in the water. Smaller males will often hide in nearby weeds and dart into the nest as they attempt to fertilize the eggs. They then quickly dart away. The size of the female plays a large role in how many eggs will be produced. A small female can produce as few as 1,000 eggs, and a large, healthy female can produce up to 100,000 eggs. The male continues to watch over the nest until

5394-430: The female. If the female stays, the pair will enter the nest and come to rest in the middle. With the male in an upright posture, the pair will touch bellies, quiver, and spawn . These actions are repeated at irregular intervals several times in a row. Once the spawning is done, the male will chase the female out of the nest and guard the eggs. The fertilization process is entirely external. The male's sperm combines with

5487-547: The females of one species to prefer the nest of another. Bluegill can theoretically hybridize with all other species in the genus lepomis, though the most common hybrid is the Greengill . The hybrid fish are aggressive and have larger mouths than their Bluegill parent. These fish also grow faster than other small mouth fish due to its bigger mouth. Greengills or hybrid bluegills are the most efficient in growth and can reach approximately 2 lbs or 0.91 kg in one year. [1] The bluegill

5580-401: The fish must get within 1.75 centimeters of the prey. In turn, bluegill are prey to many larger species, including largemouth bass , smallmouth bass , striped bass , trout , muskellunge , turtles , northern pike , yellow perch , walleye , catfish , and even larger bluegill. Herons , kingfishers , and otters have also been witnessed catching bluegill in shallow water. However,

5673-422: The fish's slow swimming and also important in the beginning stages of the fish increasing its swimming speed. The dorsal and anal fins are two types of median fins that work in parallel to balance torque during steady swimming. When swimming backwards, the bluegill utilizes a plethora of fin muscles located in various parts of its body. Backward swimming in the bluegill is more complex than steady swimming, as it

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5766-420: The gill became the hyomandibular bone of jawed fishes , which supports the skull and therefore links the jaw to the cranium. The hyomandibula is a set of bones found in the hyoid region in most fishes. It usually plays a role in suspending the jaws or the operculum in the case of teleosts . It is now accepted that the precursors of the jawed vertebrates are the long extinct bony (armoured) jawless fish,

5859-411: The head of bony fishes , such as wrasses , which have evolved many specialized feeding mechanisms . Especially advanced are the linkage mechanisms of jaw protrusion . For suction feeding a system of linked four-bar linkages is responsible for the coordinated opening of the mouth and the three-dimensional expansion of the buccal cavity . The four-bar linkage is also responsible for protrusion of

5952-538: The jaw itself (see hyomandibula ) and the hyoid arch , which braces the jaw against the braincase and increases mechanical efficiency. While there is no fossil evidence directly to support this theory, it makes sense in light of the numbers of pharyngeal arches that are visible in extant jawed (the Gnathostomes ), which have seven arches, and primitive jawless vertebrates (the Agnatha ), which have nine. Meckel's cartilage

6045-400: The jaw) are then pulled back to close the mouth, and the fish is able to grasp the prey . By contrast, mere closure of the jaws would risk pushing food out of the mouth. In more advanced teleosts, the premaxilla is enlarged and has teeth, while the maxilla is toothless. The maxilla functions to push both the premaxilla and the lower jaw forward. To open the mouth, an adductor muscle pulls back

6138-405: The lower jaw ( mandible or jawbone) is a bone forming the skull with the cranium. In lobe-finned fishes and the early fossil tetrapods , the bone homologous to the mandible of mammals is merely the largest of several bones in the lower jaw. It is referred to as the dentary bone , and forms the body of the outer surface of the jaw. It is bordered below by a number of splenial bones, while

6231-420: The lower pharyngeal jaw could be one of the reasons for the occurrence of so many cichlid species. Convergent evolution took place over the course of the cichlid radiation, synchronous with different trophic niches. The pharyngeal jaw apparatus consists of two upper and one single lower plate, all of which have dentations that differ in size and type. The structure of the lower pharynx is often associated with

6324-470: The main component of the lower jaw. But in the adult forms of osteichthyans (bony fish) and their descendants (amphibians, reptiles, birds and mammals) the cartilage was covered in bone – although in their embryos the jaw initially develops as the Meckel's cartilage. In tetrapods the cartilage partially ossifies (changes to bone) at the rear end of the jaw and becomes the articular bone, which forms part of

6417-482: The mandibular symphysis. In bony fish, the maxilla is called the "upper maxilla," with the mandible being the "lower maxilla". The alveolar process of the maxilla holds the upper teeth, and is referred to as the maxillary arch. In most vertebrates, the foremost part of the upper jaw, to which the incisors are attached in mammals consists of a separate pair of bones, the premaxillae . In bony fish , both maxilla and premaxilla are relatively plate-like bones, forming only

6510-488: The method of cooking them, bluegills are often called panfish . The IGFA all tackle world record for the species stands at 2.15 kg (4 lb 12 oz) caught from Ketona lake in Alabama in 1950. Bluegill populations are notably vulnerable to effects of angling and harvest, particularly in size-structure. Large males appear to be especially vulnerable to effects of fishing because of their tendency to guard nests in

6603-443: The more familiar use of jaws (to humans), in feeding, was selected for and became a very important function in vertebrates. Many teleost fish have substantially modified jaws for suction feeding and jaw protrusion , resulting in highly complex jaws with dozens of bones involved. Jaws are thought to derive from the pharyngeal arches that support the gills in fish. The two most anterior of these arches are thought to have become

6696-562: The mouth, and a second set of pharyngeal jaws are positioned at the back of the throat. The oral jaws are used to capture and manipulate prey by biting and crushing. The pharyngeal jaws, so-called because they are positioned within the pharynx , are used to further process the food and move it from the mouth to the stomach. Cartilaginous fishes , such as sharks and rays , have one set of oral jaws made mainly of cartilage . They do not have pharyngeal jaws. Generally jaws are articulated and oppose vertically, comprising an upper jaw and

6789-400: The oral jaw, the pharyngeal jaw has no jaw joint, but is supported instead by a sling of muscles. A notable example occurs with the moray eel . The pharyngeal jaws of most fishes are not mobile. The pharyngeal jaws of the moray are highly mobile, perhaps as an adaptation to the constricted nature of the burrows they inhabit which inhibits their ability to swallow as other fishes do by creating

6882-410: The orbital process hinges with the orbital wall and the hyoid provides the majority of suspensory support. In contrast, hyostyly involves an ethmoid articulation between the upper jaw and the cranium, while the hyoid most likely provides vastly more jaw support compared to the anterior ligaments. Finally, in euhyostyly, also known as true hyostyly, the mandibular cartilages lack a ligamentous connection to

6975-425: The premaxilla as the mouth is opened and closed. These protrusible jaws are evolutionary novelties in teleosts that evolved independently at least five times. The premaxilla is unattached to the neurocranium (braincase); it plays a role in protruding the mouth and creating a circular opening. This lowers the pressure inside the mouth, sucking the prey inside. The lower jaw and maxilla (main upper fixed bone of

7068-403: The presence of prey by detecting weak electrical fields. Sawsharks and the critically endangered sawfish have rostrums (saws) which are both electro-sensitive and used for slashing. The rostrums extend ventrally in front of the fish. In the case of hammerheads the rostrum (hammer) extends both ventrally and laterally (sideways). Teleosts have a movable premaxilla (a bone at the tip of

7161-532: The rigid neurocranium , and the superior and inferior articulations of the maxilla are joined to the anterior tips of these two bones, respectively, creating a loop of 4 rigid bones connected by moving joints. This " four-bar linkage " has the property of allowing numerous arrangements to achieve a given mechanical result (fast jaw protrusion or a forceful bite), thus decoupling morphology from function. The actual morphology of wrasses reflects this, with many lineages displaying different jaw morphology that results in

7254-403: The same cannot be said of those of the living lungfishes . The skull roof is not fully formed, and consists of multiple, somewhat irregularly shaped bones with no direct relationship to those of tetrapods. The upper jaw is formed from the pterygoids and vomers alone, all of which bear teeth. Much of the skull is formed from cartilage , and its overall structure is reduced. In vertebrates,

7347-526: The same functional output in a similar or identical ecological niche. The most extreme jaw protrusion found in fishes occurs in the slingjaw wrasse , Epibulus insidiator . This fish can extend its jaws up to 65% the length of its head. This species utilizes its quick and extreme jaw protrusion to capture smaller fishes and crustaceans. The genus this species belongs to possess one unique ligament (vomero-interopercular) and two enlarged ligaments (interoperculo-mandibular and premaxilla-maxilla), which along with

7440-414: The shallow waters of many lakes and ponds, along with streams, creeks, and rivers. They prefer water with many aquatic plants, and seclude themselves within or near fallen logs, water weeds or any other structure (natural or manmade) that is under water. They can often be found around weed beds, where they search for food or spawn . In the summer, adults move to deep, open water where they suspend just below

7533-439: The shape of the fish makes them hard to swallow. Raccoons are also believed to be among their predators. Bluegills have the ability to travel and change directions at high speeds by means of synchronized fin movements. They use notched caudal fins, soft dorsal fins , body undulations, and pectoral fins to move forward. Having a notched caudal fin allows them to accelerate quickly. The speed of their forward motion depends on

7626-404: The sides of its body immediately after being caught as part of its threat display. It typically has a yellowish breast and abdomen, with the breast of the breeding male being a bright orange. The bluegill has three anal fin spines, ten to 12 anal fin rays, six to 13 dorsal fin spines, 11 to 12 dorsal rays, and 12 to 13 pectoral rays. They are characterized by their deep, flattened bodies. They have

7719-603: The sides of the upper jaw, and part of the face, with the premaxilla also forming the lower boundary of the nostrils . Cartilaginous fish , such as sharks and rays also lack a true maxilla. Their upper jaw is instead formed from a cartilagenous bar that is not homologous with the bone found in other vertebrates. Some fish have permanently protruding upper jawbones called rostrums . Billfish ( marlin , swordfish and sailfish ) use rostrums (bills) to slash and stun prey. Paddlefish , goblin sharks and hammerhead sharks have rostrums packed with electroreceptors which signal

7812-415: The skull, however, may be reduced; there is little cheek region behind the enlarged orbits, and little, if any bone in between them. The upper jaw is often formed largely from the premaxilla , with the maxilla itself located further back, and an additional bone, the symplectic, linking the jaw to the rest of the cranium. Although the skulls of fossil lobe-finned fish resemble those of the early tetrapods,

7905-455: The so-called ostracoderms . The earliest known fish with jaws are the now extinct placoderms and spiny sharks . Placoderms were a class of fish, heavily armoured at the front of their body, which first appeared in the fossil records during the Silurian about 430 million years ago. Initially they were very successful, diversifying remarkably during the Devonian . They became extinct by

7998-564: The spawning season usually occurs in June in waters of 67 to 80 °F (19 to 27 °C). The male bluegills arrive first at the mating site. They will make a spawning bed of six to 12 inches in diameter in shallow water, clustering as many as 50 beds together. The males scoop out these beds in gravel or sand. Males tend to be very protective and chase everything away from their nests, especially other male bluegills. Some bluegills, regardless of their small size, will even attack snorkelers if they approach

8091-651: The species of food of the species. In order to crack shellfish considerable force must be generated, which is why cichlids that feed on molluscs (e.g. the cichlid bass, Crenicichla minuano ), have molariform teeth and a strengthened jawbone bone. To grab and bite prey not armoured with shells, predators need conical, bent back teeth. Herbivorous cichlids also have structural differences in their teeth. Cichlids that specialise in algae (e.g. Pseudotropheus ) tend to have small conical teeth. Species that feed on pods or seeds require large conical teeth for chewing their food. Stoplight loosejaws are small fish found worldwide in

8184-569: The strength of which they abduct or adduct fins. The flat, slender body of the bluegill lowers water resistance and allows the bluegills to cut effectively through water. The large, flexible pectoral fins allow the fish to decelerate quickly. This superior maneuverability allows the bluegill to forage and escape predators very successfully. Bluegills have a lateral line system, as well as inner ears, that act as receptors for vibration and pressure changes. However, bluegills rely heavily on sight to feed, especially in their foraging. Optimal vision occurs in

8277-955: The surface and feed on plankton and other aquatic creatures. Bluegill try to spend most of their time in water from 60 to 80 °F (16 to 27 °C), and tend to have a home range of about 320 square feet (30 m ) during nonreproductive months. They enjoy heat, but do not like direct sunlight – they typically live in deeper water, but will linger near the water surface in the morning to stay warm. Bluegill are usually found in schools of 10 to 20 fish, and these schools will often include other panfish, such as crappie , pumpkinseeds , and smallmouth bass . Young bluegills' diet consists of rotifers , copepods , water fleas , and insects (mainly chironomids ). The adult diet consists of aquatic insect larvae ( mayflies , caddisflies , dragonflies ), but can also include terrestrial insects, zooplankton , shrimp , crayfish , leeches , other worms , snails , and other small fish (such as minnows ). If food

8370-439: The time of day or season. The bluegill is noted for the large black appendage (the "ear") on each side of the posterior edge of the gill covers as well as the base of the dorsal fin. The sides of its head and chin are commonly a dark shade of blue, hence the name "bluegill". The precise coloration will vary due to the presence of neurally controlled chromatophores under the skin. The fish usually displays 5–9 vertical bars on

8463-405: The top of the maxilla, pushing the lower jaw forward. In addition, the maxilla rotates slightly, which pushes forward a bony process that interlocks with the premaxilla. Teleosts achieve this jaw protrusion using one of four different mechanisms involving the ligamentous linkages within the skull. Some teleosts use more than one of these mechanisms (e.g. Petrotilapia ). Wrasses have become

8556-412: The upper jaw) and corresponding modifications in the jaw musculature which make it possible for them to protrude their jaws outwards from the mouth . This is of great advantage, enabling them to grab prey and draw it into the mouth . In more derived teleosts, the enlarged premaxilla is the main tooth-bearing bone, and the maxilla, which is attached to the lower jaw, acts as a lever, pushing and pulling

8649-465: Was perfectly adapted to prey on free-swimming, armoured prey like arthropods, ammonites, and other placoderms. Spiny sharks were another class of fish which appeared also in the fossil records during the Silurian at about the same time as the placoderms. They were smaller than most placoderms, usually under 20 centimetres. Spiny sharks did not diversify as much as placoderms, but survived much longer into

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