Entry Category: Science and Technology

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 …

DeGray Dam and Lake

DeGray Dam, located about eight miles northwest of Arkadelphia (Clark County), impounds the 13,400-acre DeGray Lake on the Caddo River. It was built by the U.S. Army Corps of Engineers (USACE) for purposes of electricity generation and flood control, as well as establishing a drinking water supply for Arkadelphia, and is the first “pump back capable impoundment” in the Corps’s history. A reregulation dam forms a 400-acre impoundment below the main lake, providing a supply of water that can be pumped back into DeGray Lake during times of drought and used again for hydropower generation and to provide a steady flow of water on the Caddo River. The site where DeGray Dam stands had been considered for a dam since …

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 …

Derechos, Squall Lines, Downbursts/Microbursts, and “Rogue” Winds

While Arkansas makes national news far more often for its tornadoes, the state suffers its fair share of what are commonly known as straight-line winds. For example, on June 5, 2014, a weather event originating in Colorado crossed northeastern Arkansas, killing two people, derailing a train in Craighead County, and leaving thousands without power. A derecho (pronounced “deh-REY-cho”) is an event that consists of winds that create a swath of damage that extends for more than 240 miles, has minimal wind gusts of at least fifty-eight miles per hour (mph) for most of this swath, and includes multiple hurricane-force (seventy-five mph or greater) gusts. Derechos originate from what are commonly called “bow echoes,” named for their curved radar signature. About …

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 …

Dipterans

aka: True Flies
The order Diptera belongs to the Phylum Arthropoda, Subphylum Labiata, Superclass Hexapoda, and Class Insecta. Among all insect orders, the order is number two in total number of species, ranked only behind beetles (Coleoptera), with about 125,000 described species (and an estimated 1,000,000 total species). They include house flies, blow flies, mosquitoes, gnats, black flies, midges, crane flies, horseflies, fruit flies, and others. Arkansas is home to many of these species. The first true fossil dipterans are known from the Middle Triassic Period (about 240 million years ago [mya]), and became more widespread during the Middle to Late Triassic. Although modern flowering plants did not appear until the Cretaceous (around 140 mya), the original dipterans may have had a different …

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 …

Duke, Charles Sumner

A trailblazing African-American architect and engineer, Charles Sumner Duke not only designed unique public structures, but he also fought for housing rights and educational opportunities for African Americans. His powerful legacy continues in the buildings he designed, as well as in the organization he formed to facilitate the development of engineering and technological skills in youth of color. Charles Sumner Duke was born in Selma, Alabama, on July 21, 1879. His father, Jesse Duke, was the editorial writer and publisher for a local newspaper, The Herald. His mother, Willie Black Duke, was from a family of established businessmen. It was a financially secure family, allowing Duke and his siblings to take advantage of opportunities that many others in the black …

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 Biota

An endemic species is any organism that is indigenous to a restricted or defined geographical area. Arkansas has a diverse variety of endemic biota, including fungi, plants, and animals. By 2017, there were about 139 endemic species in the state, most found in the Interior Highlands (Ouachita and Ozark Mountains). A combination of biological, climatic, and/or physical factors contribute to endemism. Some species are found in specific geographical or physiographic regions of the state, such as the Gulf Coastal Plain or Interior Highlands, whereas others may be restricted to specific sites in river drainages. Around the world, endemic species can also be found in geographically and biologically isolated areas such as islands and remote island groups, such as the Galápagos …

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. …

Evans, David L.

David L. Evans worked as an engineer on the Saturn rockets and Apollo moon landing missions but became best known later for his recruitment efforts on behalf of Harvard University, where his work led to greater diversity in the student body. He was inducted into the Arkansas Black Hall of Fame in 2005. David L. Evans was born in 1939 in Wabash (Phillips County), near Helena (Phillips County), to sharecropper parents; he was the fourth of seven children. His father died when he was ten years old. Family members encouraged his mother, pregnant with her seventh child, to move to Chicago, Illinois, or Cleveland, Ohio. Instead, his mother left tenant farming and became a maid. When Evans was sixteen, his …

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 …

Famous and Historic Tree Program

The purpose of the Arkansas Famous and Historic Tree Program (AFHTP) is to create a greater awareness and appreciation of the state’s trees through the recognition of their historical background. The AFHTP used four criteria to determine the historic status of a tree or tree community. These criteria were modeled after the National Register of Historic Places criteria and include a tree’s association with significant events, people, and landmarks. Significant horticultural, ecological, or structural characteristics, or ability to yield cultural information in local, state, or national history are also assessed. The AFHTP formally originated in 1995 within Arkansas State Parks, though its establishment had been the ambition of several state agencies since the 1970s. The creation of the program led …