| Sunfish | |
|---|---|
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| Flier (Centrarchus macropterus) | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Centrarchiformes |
| Suborder: | Centrarchoidei |
| Family: | Centrarchidae Bleeker, 1859[1] |
| Type species | |
| Centrarchus macropterus Lacépède, 1801 | |
| Subfamilies | |
See text | |
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| native range of sunfish family | |
Centrarchidae, better known assunfishes orcentrarchids, is afamily offreshwaterray-finned fish belonging to theorderCentrarchiformes, native only toNorth America. There are eight universally includedgenera within the centrarchid family:Lepomis (true sunfishes),Micropterus (black basses),Pomoxis (crappies),Enneacanthus (banded sunfishes),Centrarchus (type genus, consisting solely of theflierC. macropterus),Archoplites (Sacramento perch),Ambloplites (rock basses), andAcantharchus (mud sunfish).[2] Agenetic study in 2012 suggests that the highly distinctpygmy sunfishes of the genusElassoma are also centrarchids.[3][4]
The centrarchid family comprises 38 identifiedspecies,[2] 34 of which areextant.[5] It includes many populargame fishes familiar to North Americananglers, such as therock bass,largemouth bass,bluegill,pumpkinseed,green sunfish andcrappies. Most sunfish are highly valuedpanfish forsport fishing, and have been introduced in many areas outside theirnative ranges, sometimes becominginvasive species. While edible, they are not commercially marketed asfood fish.
As their name suggests, sunfishes are most closely related to the pygmy sunfishes (Elassomatidae), which also occur in North America. Together, these two families are sister to the Chinese perches (Sinipercidae) of East Asia. These three families are among the few temperateNorthern Hemisphere members of the orderCentrarchiformes (primarily found in theSouthern Hemisphere and the tropics), and share the suborderCentrarchoidei with a group of temperate Southern Hemisphere fishes that include thejutjaw,oldwife, and the Australiantemperate perches.[6][7]
Family members are distinguished by having a laterally compressed body shape, 6 to 9 anal spines, and 2 dorsal fins (spinous first dorsal and rayed second dorsal) which are fused.[8] The number of dorsal spines varies from 6 to 13. All species inMicropterus andLepomis have 3 anal spines, which distinguishes them from the other genera in the family.[8] Thepseudobranch is small and concealed. Body size varies widely within the family with theblack-banded sunfish at just 8 cm (3.1 in) in length, while thelargemouth bass is reported to reach almost 1 m (3.3 ft) in extreme cases.[9]
Many of the species within Centrarchidae can be separated into two main groups based on the two most common genera (Micropterus andLepomis). Species in the generaLepomis are defined by a deep or more round body shape, smaller mouths, and obtaining food throughsuction feeding.[2][10] Species in the generaMicropterus are defined by a more streamlined body shape, larger mouths, and consuming prey primarily byram feeding methods.[2][10]
Centrarchids prefer clear, warm, and slower-moving water, and are commonly found in habitats such as lakes, ponds, medium to low flow streams and rivers, and swamps.[11] They also prefer to live in and around aquatic vegetation so they can get adequate coverage from predators. While few species in the family diverge from the aforementioned habitat list, theSacramento perch can survive in habitats with unusually high alkalinity, salinity, and temperatures.[11] Centrarchids can be found in various locations within thewater column and their exact preference is species specific. For instance,bluegill (Lepomis macrochirus) mainly inhabit the deeper littoral zones, whilegreen sunfish (Lepomis cyanellus) prefer habitats near the shoreline and shallower areas.[12] Suction feeders within the family (i.e.Lepomis) generally feed off the bottom of their habitat, while ram feeders (i.e.Micropterus) generally feed in more open areas known as thelimnetic zone.[13] Centrarchids diet consists of macro-invertebrates (e.g. insects, snails and crayfish) and other fish found in their habitat.[11]
In freshwater systems, water temperature is determined by many abiotic factors, with air temperature being one of the most significant contributors.[14] As in otherectotherms, many physiological processes and behaviors in Centrarchidae, such as feeding and reproduction, are heavily impacted by the temperature in their environment.[15] All species in the family Centrarchidae are consideredwarmwater adapted species.[16] In general, warmwater adapted species are characterized as being larger at higher temperatures and lower latitudes.[17] The optimal temperature range of most species in the family is 28 °C(82 °F) to 32 °C(90 °F), although they can survive and reproduce in temperatures that are outside of this optimum range.[10] Increases in temperature outside the optimal range for centrarchids can have negative effects, such as speeding up reproductive maturity or increasing mortality after the first reproductive event.[18] The lethal temperature range varies widely in the family, but some species have been seen to survive water temperatures as low as 1 °C(33 °F) or as high as 41 °C(106 °F).[19]
Centrarchids generally spawn in the spring, and juveniles emerge in the late spring to early summer.[20] The transition from winter to spring conditions (i.e. melting of ice-cover, increase in day length, and increased food availability) is the main cue for centrarchids to begin preparing for reproduction.[15] All species within Centrarchidae, except for those in the genusMicropterus, develop breeding coloration in both males and females (although less defined in females) during the breeding season.[2] The process of courtship and reproduction is nearly identical for all species in the family, which is a major reason for the high levels of hybridization within Centrarchidae.[21] With that said, there are some mechanisms in place to prevent hybridization, such as intricate morphology of the operculum inLepomis, which assists in recognition of conspecific mates.[2]
To initiate reproduction, males dig a deep circular depression in the substrate with their caudal fins to create a nest,[11] which they will aggressively defend from intruding males.[2] Males and females then undergo a courtship dancing ritual before the female deposits her eggs into the male's nest.[11] Multiple females may deposit eggs in a single nest.[10] Larger males usually attract more mates and also take better care of their offspring.[22]Male parental care includes nest building, nest guarding, guarding of eggs and fry, and nest fanning (aerating eggs).[23]
Males unsuccessful at courtship may exhibit acheater strategy where they sneak fertilizations of female's eggs by various behavioral methods.[24] This is commonly seen with smaller males in the genusLepomis.[8]
The native range of Centrarchidae is confined within North America, covering most of the United States and stopping in southern Canada. The northern edge of the native range is heavily bound by temperature due to reduced foraging ability and growth in cold weather and subsequent starvation in winter months.[10][25] As a result, centrarchid distributions and range in any place they are found will be restricted by cold temperatures.[10]
The ability to adapt to cold temperatures at the edge of the sunfish range varies widely within the family.Largemouth bass (Micropterus salmoides) have no cold acclimation ability as seen through the strict maintenance of the northern boundary of the species range.[26] Other species likesmallmouth bass (Micropterus dolomieu) andgreen sunfish (Lepomis cyanellus) have exhibited signs of minor cold-water adaptation and have even experienced slight range expansions into colder habitats.[26]
If air temperatures continue to rise in the next 50 to 100 years as predicted,[27] warmwater species like centrarchids will likely experience range expansions northward and see an overall increase in occupiable habitat.[28][14] This range expansion can have grave consequences for other freshwater fishes however, as many centrarchids are dominant top predators which can severely alter the community structure of non-native ecosystems and drive the extinction of other native predators.[29]
While centrarchids are native to only North America, they can be found worldwide due to introductions on multiple continents, including Europe, South America, Africa, and Asia.[11] At least 18 species of Centrarchidae are North American exports.[10] Its multi-continental spread is mostly due to the high popularity of the family (especially from the generaMicropterus) as freshwater game fish that are frequently stocked forrecreational fishing all around Europe.[10][11]
Across the globe, invasive and introduced centrarchids pose a great threat to native species in the areas they invade.[10][30] There are multiple confirmed instances of largemouth bass(Micropterus salmoides) severely altering and reducing native fish populations in Italy, South Africa, Japan, and Madagascar and even causing the local extinction of any species of the familyCyprinodontidae within the waterbodies they have invaded in Mexico.[10]
The earliest fossils of Centrarchidae are fromlatest Eocene toearly Oligocene deposits fromMontana andSouth Dakota, belonging to several as yet undescribed species and the two extinct genera †Plioplarchus and †Boreocentrarchus. BothPlioplarchus andBoreocentrarchus are classified in the subfamily Centrarchinae, because these species possess more than three anal fin spines.[31]
Recent genetic evidence suggests the followingtaxonomy of the centrarchid genera and species:[32][33]
| Centrarchidae |
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The 5th edition ofFishes of the World recognises three subfamilies; theLepominae, which contains the generaAcantharchus,Lepomis, andMicropterus; theElassomatinae, which consists solely of the highly distinct genusElassoma (treated byFishbase as a separate family, the Elassomatidae);[34] and theCentrarchinae, which contains all of the remaining genera.[35]
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