Zoology

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Entry Category: Zoology

Caddo Mountain Salamander

aka: Plethodon caddoensis
The Caddo Mountain salamander (Plethodon caddoensis) is a slender, medium-sized (90–100 millimeters in total length) terrestrial salamander. It is one of twenty or so members of the caudate family Plethodontidae that can be found in Arkansas. Adults of this species possess numerous tiny white spots and/or brassy flecks on the back and tail; the dorsal body color is otherwise uniformly black. The lateral body surfaces are creamy white in appearance. The throat region is distinctly pale or white. Juveniles may lack much of the lateral body coloration. This species is one of three endemic salamanders known to exist in Arkansas and is primarily confined to the Caddo Mountains area of the southern Ouachita National Forest and several outlying areas in …

Carps

In Arkansas, carps are an invasive (exotic or non-native) species whose introduction has caused economic and/or environmental damage. To date, there are five species of invasive carps that have entered or have been deliberately introduced into Arkansas for various reasons, and all belong to the order Cypriniformes and the minnow family Cyprinidae. Many of these fish originated from Asia or Europe, were introduced into North America, and pose a major threat to the ecology of native fishes, the environment, and the economy of fisheries in Arkansas. The longer it takes to respond to the damage done to an ecosystem done by these fish, the more money and time must be spent restoring and protecting that ecosystem. Grass Carp The grass …

Cave Crayfishes

aka: Troglobitic Crayfishes
Crayfishes belong to the Phylum Arthropoda, Subphylum Crustacea, Class Malacostraca, Order Decapoda, and Family Cambaridae. Crayfishes are a taxonomically diverse cosmopolitan group with more than 669 species worldwide. There appear to be two centers of geographic diversity, one in southeastern Australia (Southern Hemisphere center) and one in the southeastern United States (Northern Hemisphere center) in the southeastern Appalachian Mountains. Obligate cave-dwelling taxa in the United States occur in five main karst (limestone) geographic regions: (1) the Cumberland Plateau of the southern Appalachians of eastern Kentucky, eastern Tennessee, and northern Alabama; (2) the Interior Lowlands of southern Indiana, western Kentucky, and northwestern Tennessee; (3) the Greenbrier Valley of West Virginia; (4) the Ozark Plateau of southwestern Missouri, northern Arkansas, and eastern …

Centipedes

Centipedes (class Chilopoda) are myriapods that include two subclasses, five living orders, and about 2,800 described species (out of an estimated worldwide fauna of approximately 8,000 species) within about twenty-three families. Their fossil history dates back over 410 million years ago to the late Silurian Period of the Paleozoic Era. In terms of worldwide geographic distribution, centipedes are found north of the Arctic Circle and inhabit all subarctic regions but are most abundant in temperate, desert, and tropical areas, where they are common terrestrial invertebrates. Humans have unintentionally introduced several species onto most oceanic islands. However, one order (Craterostigomorpha) is endemic to New Zealand and Tasmania. Members of the families Oryidae and Scutigeridae and of the subfamily Otostigminae have been …

Central Mudminnows

aka: Umbrids
The central mudminnow (Umbra limi) is a small (51 to 132 mm [2 to 5 in.]) fish that belongs to the Family Umbridae and Order Esociformes. There are three other North American members of the family: the eastern mudminnow (U. pygmaea) of the Eastern Seaboard and Atlantic Coastal Plain, the Alaska blackfish (Dallia pectoralis) that occurs in Alaska and adjacent Siberia, and the Olympic mudminnow (Novumbra hubbsi) of the Olympic Peninsula of Washington. All of these are strictly Northern Hemisphere freshwater species. A third Umbra species, the European Mudminnow (U. krameri), occurs widely throughout Europe. Mudminnows are most closely related to esocids (pikes and pickerels). The fossil record includes specimens that date back to the Oligocene of Eurasia and North …

Centrarchid Fishes

aka: Sunfishes
The Centrarchidae (sunfishes) are a family of North American native freshwater ray-finned fish belonging to the order Perciformes. There are eight genera and thirty-eight species in the family, thirty-four of which (eighty-nine percent) are extant. The group includes several game and pan fishes familiar to anglers, including smallmouth and largemouth basses, bluegills (“bream”), and crappies. The eight genera are: Acantharchus (mud sunfish), Ambloplites (rock basses), Archoplites (Sacramento perch), Centrarchus (flier), Enneacanthus (banded sunfishes), Lepomis (sunfishes), Micropterus (black basses), and Pomoxis (crappies). In Arkansas, there are five genera and twenty-two species of centrarchids, of which eighteen are native and four are introduced. The latter includes the rock bass (Ambloplites rupestris), redbreast sunfish (Lepomis auritus), redeye bass (Micropterus coosae), and shoal bass …

Cestodes

aka: Tapeworms
Cestodes (tapeworms) include flatworms belonging to the phylum Platyhelminthes, class Cestoidea, subclasses Cestodaria (two orders) and Eucestoda (sixteen orders), and about fifty-nine families. The subclass Cestodaria includes monozoic (unsegmented) tapeworms containing only a single set of male and female reproductive organs; these are parasitic in the intestinal tract and body cavity of fishes and turtles. The subclass Eucestoda is made up of polyzoic (segmented) or monozoic cestodes of varying structure and parasitic in the intestines of vertebrates. To date, there are more than 5,000 described species that, as endoparasites, infect all vertebrate classes. The classification of tapeworms remains ambiguous using classical morphological studies alone, and, although some studies have been done recently using molecular tools, further attention is needed to …

Chordate Parasites

aka: Parasitic Chordates
Although the majority of the world’s parasites are protists, helminths, invertebrates, and other miscellaneous groups of organisms, parasitism has also arisen within animals of the phylum Chordata (subphylum Vertebrata). All chordates, at some time in their development, possess five derived morphological characteristics as follows: (1) a dorsal tubular or hollow nerve cord, (2) a notochord, (3) pharyngeal gill slits or pouches, (4) an endostyle, and (5) a post-anal tail. Some examples of parasitic chordates are remoras (which attach to sharks and rays); the jawless fishes (lampreys and hagfishes), which prey upon other fishes; some birds that practice brood parasitism; and vampire bats. The Superclass Agnatha has both extinct groups and extant species, including the “jawless” fish (lamprey and hagfish) that …

Cladocerans

aka: Water Fleas
Water fleas (cladocerans) belong to the Phylum Arthropoda, Subphylum Crustacea, Class Branchiopoda, and Order Cladocera. Over 700 species and more than 100 genera have been recognized, but many additional species are surely undescribed. The genus Daphnia alone contains around 150 species. The order forms a monophyletic group, which is divided into four suborders and eleven families as follows: Anomopoda (five families), Ctenopoda (two families), Haplopoda (one family), and Onychopoda (three families). Although a complete survey of the cladocerans of Arkansas has not been given, about twenty species/taxa within five families have been reported. Cladocerans first appeared in the Permian. Until recently, the evolutionary history of cladocerans has been obscured by a mixture of erroneous fossil identifications and assumptions. However, knowledge …

Cnidarians

aka: Hydroids
aka: Corals
aka: Jellyfishes
aka: Sea Anemones
Cnidarians (hydroids, jellyfishes, corals, and sea anemones) form a diverse phylum (Cnidaria, old Phylum Coelenterata) that contains more than 10,000 species. The phylum also includes the parasitic Myxozoa. Typical cnidarians inhabit aquatic (predominantly marine) environments. Cnidarians are divided into two major groups: the Anthozoa (corals, sea anemones, and sea pens), which live as sessile polyps, and the subphylum Medusozoa (Hydra, jellyfishes, and sea wasps), many of which form a free-swimming medusa as well as polyps. There are five main classes: Anthozoa, Cubozoa, Hydrozoa, Scyphozoa, and Staurozoa. Only a few cnidarians can be found in Arkansas, including a jellyfish seen in lakes and rivers. In terms of evolutionary relationships, modern molecular phylogenetic results support the notion that anthozoans represent the first …

Coccidia

Coccidians are microorganisms belonging to the Phylum Apicomplexa and Suborder Eimeriorina, which includes eight to thirteen families, about 39 genera, and well over 2,000 species. These protists are intracellular (meaning they function inside the cell) parasites of medical and veterinary importance, including those in the genera Caryospora, Cryptosporidium, Cyclospora, Eimeria, Isospora, Sarcocystis, and Toxoplasma. Most are considered intestinal parasites that infect both invertebrates as well those animals in all vertebrate classes. These parasites cannot complete their life cycle without exploiting a host. Coccidiosis is a general term for the disease they can cause, and it is recognized as a major health concern in wild animal populations, domestic animals, and zoo animals. However, some infections appear not to cause any pathology …

Cockroaches

aka: Blattodea
Cockroaches belong to the Phylum Arthropoda, Subphylum Labiata, Superclass Hexapoda, Class Insecta, and Order Blattodea. The order includes approximately 4,600 species in almost 500 genera and seven families. Very likely at least twice this number remains to be discovered and described worldwide. Some of the most well-known cockroach examples are two pest species belonging to the family Blattidae: the American cockroach (Periplaneta americana) and German cockroach (Blattella germanica). Cockroaches are considered one of the most successful groups of invertebrates because of their adaptability in various environmental conditions and occupy a very wide range of habitats from caves to mountains to rainforests to deserts. As a group, cockroaches also exhibit a remarkable diversity of form, coloration, size, and behavior. Although no …

Collembollans

aka: Springtails
Springtails (collembolans) belong to the phylum Arthropoda and subphylum Hexapoda. They form the largest (about thirty-five families and 9,000 different species) of the three lineages of modern hexapods that are no longer considered to be included in the class Insecta (the other two are the proturan and dipluran apterygotes). Since each has internal mouthparts, the three are sometimes grouped together into a class called Entognatha. However, they do not appear to be any more closely related to one another than they all are to insects, which have external mouthparts. Indeed, they do share some features of insects, such as a body divided into three parts, a head with antennae, a three-segmented thorax, and each segment having a pair of jointed …

Crustaceans

Crustaceans (subphylum Crustacea) are a very large and diverse group of arthropods (invertebrate animals having an exoskeleton, jointed appendages, and segmented bodies). Crustaceans are distinguished by having paired mandibular jaws and maxillae, along with two pairs of antennae. Recent classifications include six classes within crustaceans—Branchiopoda, Remipedia, Cephalocarida, Maxillopoda, Ostracoda, and Malacostraca. The Classes of Crustacea Class Branchiopoda includes several groups of primitive aquatic and marine animals, including clam shrimp, the small fairy shrimp (less than one centimeter in length and living in temporary pools), and the “living fossil” tadpole shrimp. The most noteworthy brachiopods are the cladocerans, or water fleas, that make up many of the zooplankton in Arkansas lakes and ponds. These small, free-swimming animals are a critical food …

Cyprinids

The Cyprinidae is a diverse family of mainly freshwater fishes belonging to the ostariophysian order Cypriniformes, collectively called cyprinids. They include carps, true minnows, and their relatives. The Cyprinidae is the largest and most diverse fish family and, in general, the largest vertebrate animal family, with about 3,160 species, of which only 1,270 are extant, divided into about 376 genera. The family occurs in Africa, Eurasia, and North America (northern Canada to southern Mexico). Only two species of cyprinids occur in true marine waters, daces (Tribolodon brandtii and T. sachalinensis) from eastern Asia, and a few stray into brackish water only very rarely. More than sixty-two species of cyprinids are known from Arkansas, which represents almost a third of the …

Dellinger, Samuel Claudius

Samuel Claudius Dellinger was curator of the University of Arkansas Museum in Fayetteville (Washington County) and head of the Department of Zoology for over thirty years. As curator, he built the museum’s archaeology collection into one of the best in the nation. In Dellinger’s view, the museum was, first and foremost, an educational resource for the people of Arkansas, and he worked to generate interest in it from the university community and the general public. Samuel Dellinger was born on January 14, 1892, in Iron Station (later Lincolntown), North Carolina, to Robert H. and Laura Loftin Dellinger. After graduating from high school, Dellinger attended Trinity College (later Duke University), where he was a varsity wrestler and swimmer. Dellinger earned his …

Diplurans

aka: Two-Pronged Bristletails
The primitive insects known as diplurans belong to the phylum Arthropoda, subphylum Hexapoda, class Insecta and order Diplura. They are considered to have three lineages: the Campodeoidea, Japygoidea, and Projapygoidea. These superfamilies are defined morphologically by three different types of cerci (paired appendages) found across all the dipluran families. There are ten families in this cosmopolitan order distributed from the tropics to the temperate zones. Diplurans belong to one of the four groups of Hexapoda, with other primitive apterygote insects, including springtails (Collembola) and coneheads (Protura). There are about 800 described species, of which around seventy (9%) occur in North America, twelve (2%) in the United Kingdom, and two (0.3%) in Australia. In 2016, species of diplurans were reported from …

Dipteran Parasites

aka: Parasitic Dipterans
aka: flies
aka: mosquitos
aka: gnats
The order Diptera belongs to the Phylum Arthropoda and Class Insecta. The order ranks number two among all insect orders—only behind beetles (Coleoptera)—with about 125,000 described species (there are an estimated 1,000,000 total species), many of which are considered parasitic or serve as vectors for diseases. There are two main groups (suborders): the Nematocera with seven infraorders and Brachycera with six infraorders. Dipterans—including the sixty species of mosquitoes that occur in Arkansas and Missouri—can be irritating to humans and harmful to livestock and other animals. A major repository of voucher specimens of dipterans in Arkansas is the Entomology Arthropod Museum at the University of Arkansas in Fayetteville (Washington County). It houses the largest research and reference collection of insects and …

Dog Heartworms

aka: Dirofilaria immitis
The canine heartworm (Dirofilaria immitis) is a filarial parasite that belongs to the Phylum Nematoda, Class Secertenea, Order Spirurida, and Family Onchocercidae. There are two subgenera: Dirofilaria and Nochtiella. This parasite is often found in wild and domestic canids throughout the world, especially in the United States where it is endemic from the East to the Midwest, the southeastern Atlantic seaboard, and the southern Gulf Coast. Transmission of the parasite occurs throughout the United States (even Alaska) and in the warmer regions of Canada. In the United States, the highest infection rates are found within 241 km (150 mi.) of the coast from Texas northeast to New Jersey, and along the Mississippi River Valley and its major tributaries. The parasite …

Earwigs

Earwigs belong to the Phylum Arthropoda, Class Insecta, and Order Dermaptera. It is one of the comparatively species‐poor insect orders, as there are about 2,200 extant species within eleven families. About twenty-five species occur in North America, sixty in Australia, and forty-five in Europe. Earwigs are found on all continents except Antarctica and occur in northern latitudes as far north as Greenland. Earwigs exhibit their major diversity in the tropics and have a strong preference for warm and moist environments; few survive winter outdoors in cold climates. The overwhelming majority of earwig species are in the suborder Forficulina, grouped into nine families of 180 genera, including the common European earwig, Forficula auricularia. As of 2020, no earwigs have been reported …

Elk

Among the many success stories involving wildlife in Arkansas, a high-profile example is the elk of the Buffalo National River country. Wiped out in pioneer and early settlement days, the elk were brought back beginning in 1981, and, since then, the big animals have become well enough established that they can be hunted on a limited basis. The elk have also become a reliable tourist attraction in Newton County and the surrounding area. Elk were native to Arkansas but were wiped out by changing habitat, mostly the clearing of land. The variety in the area in the early days was the eastern subspecies of elk, which is extinct. By the time Arkansas became a state in 1836, elk were dwindling, …

Endemic Darters

Forty species/subspecies of darters live in Arkansas; many of them are beautifully colored, especially males during the breeding season. Of these forty, five species are endemic to Arkansas, meaning that they occur nowhere else on the planet. Those five endemic darters are the beaded darter (Etheostoma clinton), strawberry darter (Etheostoma fragi), yellowcheek darter (Etheostoma moorei), paleback darter (Etheostoma pallididorsum), and the most recently described Ouachita darter (Percina brucethompsoni). The beaded darter, Etheostoma clinton (named after Bill Clinton, the forty-second president of the United States) was described (elevated) by Richard Mayden of St. Louis University in Missouri and Steven Layman of Kennesaw, Georgia, from specimens collected in the upper Ouachita and Caddo rivers. It was formerly known as the speckled darter …

Endemic Isopods

Isopods belong to the Phylum Arthropoda, Subphylum Crustacea, Class Malacostraca, and Order Isopoda, and include pillbugs, sowbugs, woodlice, and their relatives. Isopods are cosmopolitan organisms that inhabit saltwater and freshwater habitats, including subterranean waters, but they can also be found in terrestrial environments. There are over 10,000 species of isopods worldwide in eleven suborders with about 4,500 species found in marine environments, 500 species in freshwater environments, and 5,000 species on land. Their fossil record dates back to the Carboniferous Period of the Paleozoic (some 300 million years ago) when they lived in shallow seas. Isopods range in length from thirty micrometers (microcerberid isopods) to 500 mm (19.7 in.) for the giant Antarctic isopod (Bathynomus giganteus). The majority of North …

Endemic Madtoms

aka: Ouachita Madtoms
aka: Caddo Madtoms
Two miniature catfishes are endemic to Arkansas—that is, they occur only in Arkansas and nowhere else on Earth. Both of these endemic fishes, the Ouachita madtom (Noturus lachneri) and the Caddo madtom (Noturus taylori), are taxonomically placed in the genus Noturus, the madtoms, which are contained within the catfish family Ictaluridae. Noturus lachneri was originally described by William Ralph Taylor in 1969 from the type locality of the Middle Fork of Saline River at State Highway 7, 11.2 miles (18.1 kilometers) north of Mountain Valley in Garland County. It was believed to be confined to the upper Saline River drainage until a Northeastern Louisiana University graduate student discovered it in a small tributary of the main Ouachita River just below …

Esocids

aka: Pikes
Esocids belong to the order Esociformes and family Esocidae. They were endemic to the Northern Hemisphere of North America and Eurasia during the Paleogene (66 to 23 million years before present). The only living genus is Esox (pikes and pickerels) and it includes seven species; four of those species occur in North America, and five (one introduction) of the seven can be found in Europe and Asia. In the United States, the natural range of esocids is restricted to regions east of the Rockies; however, many introductions have been made in the west. In Arkansas, there are four species: the grass pickerel (Esox americanus), northern pike (E. lucius), muskellunge (E. masquinongy), and chain pickerel (E. niger). Two of these, E. …

Exotic Fish

An exotic (or invasive) species is any plant or animal that is not native to an ecosystem and that can potentially cause economic or environmental harm, as well as damage to native animal or human health. Several species of exotic fishes in Arkansas have the capability to cause significant economic losses to fisheries and reduce opportunities for effective uses of valued aquatic natural resources. These include seven species within the minnow family Cyprinidae (now considered Leuciscidae), five species in the trout and salmon family Salmonidae, a single species of cichlid (Cichlidae), snakehead (Channidae), smelt (Osmeridae), and yellow perch (Percidae), and two species of pikes (Esocidae). CYPRINIFORMES: CYPRINIDAE (LEUCISCIDAE) Rudd or pearl roach (Scardinius erythrophthalmus). This fish apparently entered the United …

Extinct Animals [Historic Period]

Arkansas has undergone many changes over geologic time. The climate has ranged from tropical, supporting dinosaurs in the Mesozoic period, to the cold period at the end of the Cenozoic period, known as the Pleistocene epoch. The most recent drastic climate change began about 1.6 million years ago during the Pleistocene epoch, the planet’s most recent ice age. Glaciers covered much of North America. They did not reach Arkansas but occurred as far south as the Missouri River. During warm periods, the glaciers melted and sent millions of gallons of water through Arkansas on its way to the sea. Many types of animals that lived here have disappeared. If they had a hard shell or a bony skeleton, fossil records …

Extinct Animals [Prehistoric Period]

Fossils and sedimentary rock layers contribute to current knowledge of the animals that lived in Arkansas in the geologic past. A careful examination of these layers and the types of fossils contained in them reveals clues about the age of the rock and the different environments of the past. In the older deposits, evidence indicates that all of Arkansas was covered by the ocean at various times; fossils of marine animals are found as well as sequences of rock that display patterns only found in marine sedimentary deposits. In some of the most recent deposits, the remains of land animals that walked the earth just a few thousand years ago have been found. All but the most recent of the …

Fairy Shrimps

aka: Anostraca
The Order Anostraca (Phylum Arthropoda, Subphylum Crustacea, Class Branchiopoda) includes the fairy or brine shrimps. Worldwide, there are 300 species within twenty-six genera placed in eight families: Artemiidae (one genus, nine species), Branchinectidae (one genus, forty-five species), Branchipodidae (five genera, thirty-five species), Chirocephalidae (nine genera, eighty-one species), Parartemiidae (one genus, thirteen species), Streptocephalidae (one genus, fifty-six species), Tanymastigidae (two genera, eight species), and Thamnocephalidae (six genera, sixty-two species). In Arkansas, seven anostracan species are known: Eubranchipus neglectus, E. serratus, E. moorei, Branchinecta packardi, Thamnocephalus platyurus, Streptocepalus sealii, and S. texanus. Fairy shrimps are very primitive organisms believed to have diverged during the Ordovician period from the main line of the Branchiopoda. Their fossil record dates back to the Devonian, although …

Fish

Arkansas fishes are a combination of abundant and rare species—primitive and ancestral, commercial and sport, game and non-game, native and introduced, and transplanted and exotic. There are approximately 233 fish species in Arkansas. Arkansas has a relatively rich fish fauna compared to neighboring states (which range between 148 and 319 fish species). Some species, such as the western mosquitofish (Gambusia affinis), are common statewide, whereas other species, such as the yellowcheek darter (Etheostoma moorei), have more restricted distributions. Distinct differences in topography and geology between northwestern (upland) and southeastern (lowland) Arkansas have led to distinctly different groups of fish species developing in each of these regions. For example, because of an abundance of clear, gravel-bottom, flowing streams in northwestern Arkansas, …