Centrarchidae - WikiHQ

Centrarchidae, better known as sunfishes or centrarchids, is a family of freshwater ray-finned fish belonging to the order Centrarchiformes, native only to North America. There are eight universally included genera within the centrarchid family: Lepomis (true sunfishes), Micropterus (black basses), Pomoxis (crappies), Enneacanthus (banded sunfishes), Centrarchus (type genus, consisting solely of the flier C. macropterus), Archoplites (Sacramento perch), Ambloplites (rock basses), and Acantharchus (mud sunfish).

The centrarchid family comprises 38 identified species, 34 of which are extant. It includes many popular game fishes familiar to North American anglers, such as the rock bass, largemouth bass, bluegill, pumpkinseed, green sunfish and crappies. Most sunfish are highly valued panfish for sport fishing, and have been introduced in many areas outside their native ranges, sometimes becoming invasive species. While edible, they are not commercially marketed as food fish.

Evolution

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 temperate Northern Hemisphere members of the order Centrarchiformes (primarily found in the Southern Hemisphere and the tropics), and share the suborder Centrarchoidei with a group of temperate Southern Hemisphere fishes that include the jutjaw, oldwife, and the Australian temperate perches.

The earliest fossils of Centrarchidae are from latest Eocene to early Oligocene deposits from Montana and South Dakota, belonging to several as yet undescribed species. Two extinct genera are also known: †Plioplarchus from the Early Oligocene to the Middle Miocene of the Dakotas & Oregon, and †Boreocentrarchus from the Late Oligocene or Early Miocene of southern Alaska (making it one of the northernmost known members of the family). Both Plioplarchus and Boreocentrarchus are classified in the subfamily Centrarchinae, because these species possess more than three anal fin spines.

Taxonomy

The family is classified as follows:

Family Centrarchidae
Subfamily Centrarchinae
Acantharchus Gill, 1864
Ambloplites Rafinesque, 1820
Archoplites Gill, 1861
Centrarchus Cuvier, 1829
Enneacanthus Gill, 1864
Pomoxis Rafinesque, 1818
†Boreocentrarchus Schlaikjer, 1937 (fossil; late Oligocene/early Miocene of Alaska)
†Plioplarchus Cope, 1883 (fossil; Oligocene to Miocene of western North America)
Subfamily Lepominae
Lepomis Rafinesque, 1816
Micropterus Lacépède, 1802

Phylogeny

Recent genetic evidence suggests the following taxonomy of the centrarchid genera and species:

The 5th edition of Fishes of the World recognises three subfamilies; the Lepominae, which contains the genera Acantharchus, Lepomis, and Micropterus; the Elassomatinae, which consists solely of the highly distinct genus Elassoma (treated by Fishbase as a separate family, the Elassomatidae); and the Centrarchinae, which contains all of the remaining genera. The more recent Eschmeyer's Catalog of Fishes again treats Elassomatidae as a distinct family, with Centrarchidae composed of Lepominae and Centrarchinae. The number of dorsal spines varies from 6 to 13. All species in Micropterus and Lepomis have 3 anal spines, which distinguishes them from the other genera in the family.

Many of the species within Centrarchidae can be separated into two main groups based on the two most common genera (Micropterus and Lepomis). Species in the genera Lepomis are defined by a deep or more round body shape, smaller mouths, and obtaining food through suction feeding. Species in the genera Micropterus are defined by a more streamlined body shape, larger mouths, and consuming prey primarily by ram feeding methods. 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, the Sacramento perch can survive in habitats with unusually high alkalinity, salinity, and temperatures. 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 the limnetic zone. Centrarchids diet consists of macro-invertebrates (e.g. insects, snails and crayfish) and other fish found in their habitat. As in other ectotherms, many physiological processes and behaviors in Centrarchidae, such as feeding and reproduction, are heavily impacted by the temperature in their environment. All species in the family Centrarchidae are considered warmwater adapted species. In general, warmwater adapted species are characterized as being larger at higher temperatures and lower latitudes. 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. 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).

Reproduction

Centrarchids generally spawn in the spring, and juveniles emerge in the late spring to early summer. 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. With that said, there are some mechanisms in place to prevent hybridization, such as intricate morphology of the operculum in Lepomis, which assists in recognition of conspecific mates. Male parental care includes nest building, nest guarding, guarding of eggs and fry, and nest fanning (aerating eggs).

Males unsuccessful at courtship may exhibit a cheater strategy where they sneak fertilizations of female's eggs by various behavioral methods. This is commonly seen with smaller males in the genus Lepomis. As a result, centrarchid distributions and range in any place they are found will be restricted by cold temperatures.

If air temperatures continue to rise in the next 50 to 100 years as predicted, warmwater species like centrarchids will likely experience range expansions northward and see an overall increase in occupiable habitat.

Invasive range

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. There are multiple confirmed instances of largemouth bass (Micropterus nigricans) 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 family Cyprinodontidae within the waterbodies they have invaded in Mexico.