Zoology

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Entries - Entry Category: Zoology

Acanthocephalans

aka: Spiny-Headed Worms
aka: Thorny-Headed Worms
These cylindrical metazoan worms, superficially similar to nematodes, belong to the phylum Acanthocephala and include four classes, ten orders, twenty-six families, and about 1,300 species. Recent molecular studies suggest that Rotifera (rotifers) and Acanthocephala are phylogenetically related sister groups. Adult members are highly specialized, dioecious (having distinct male and female colonies, as opposed to hermaphroditic) parasites of the intestinal tract of a variety of vertebrates (but not generally humans). They cause serious disease fairly rarely. The life cycle involves at least two hosts, either an aquatic intermediate host (Amphipoda, Copepoda, Isopoda, and Ostracoda) or terrestrial intermediate hosts including insects, crustaceans, and myriapods. Fishes, amphibians, reptiles, birds, and mammals serve as definitive hosts. Acanthocephalans range from 0.92 to 2.4 millimeters long …

Alligator Snapping Turtle

The alligator snapping turtle (Macrochelys temminckii) is North America’s largest freshwater turtle. This turtle is found primarily in major rivers, streams, swamps, and oxbow lakes throughout much of the south-central United States—all around the states of Arkansas and Mississippi and in portions of Texas, Oklahoma, Kansas, Missouri, Illinois, Iowa, Georgia, and Florida. Alligator snapping turtles have distinct morphological features that distinguish them from their closest cousin, the snapping turtle (Chelydra serpentina). For example, the dorsal shell, or carapace, of the alligator snapping turtle has three prominent keels (ridges on the carapace), whereas the keels of the snapping turtle are low and become less conspicuous with age. The tails of both species have three rows of tubercles (warty projections), but these scales …

American Alligator

The American alligator (Alligator mississippiensis) belongs to the class Reptilia, order Crocodylia, superfamily Alligatoroidea, and family Alligatoridae. There are seven species in the family endemic to the New World tropics, with an eighth species occurring in the warmer temperate regions of China. The American alligator is endemic to the southeastern coastal plain of the United States, where it inhabits freshwater wetlands such as streams, reservoirs, ponds, lakes, coastal marshes, bayous, oxbows, and cypress swamps associated with larger rivers in parts of Alabama, Arkansas, Florida (and some Florida Keys), Georgia, Louisiana, Mississippi, North Carolina, Oklahoma, South Carolina, Texas, and Virginia; it also occurs in the lower Rio Grande Valley of Texas south of San Antonio, and farther south into the thornscrub …

American Eel

The American eel (Anguilla rostrata) belongs to the order Anguilliformes and family Anguillidae. Common names include Atlantic eel, common eel, freshwater eel, silver eel, yellow-bellied eel, green eel, black eel, bronze eel, elver, whip, and easgann. This family includes about eighteen facultative catadromous species of eels. The American eel ranges from Greenland and Iceland and all the drainages of eastern North America along the Atlantic and Gulf slopes west to New Mexico and south to Venezuela and islands of the Caribbean and West Indies across a latitudinal range of 5 to 62° N. In North America, A. rostrata occurs inland from eastern Canada to the Great Lakes, in the headwaters of many Atlantic and Gulf slope rivers, and in the …

Amphibians

Arkansas has within its borders a modest assemblage of salamanders, frogs, and toads, which are taxonomically grouped in the class Amphibia and, therefore, are commonly called amphibians. Amphibians were the first tetrapods (four-legged vertebrates) to walk on land, having come from an early-evolving group of lobe-finned fishes nearly 360 million years ago. Today’s amphibians possess a mostly bony skeleton with a strong “backbone” comprising a series of interlocking vertebrae. Salamanders are termed caudates because they possess a tail in both the juvenile and adult forms, whereas frogs and toads (collectively called anurans) lack tails as adults even though the larvae (tadpoles) possess them. The study of amphibians has been traditionally linked with the study of reptiles in the professional field …

Amphipods

aka: Scuds
Amphipods belong to the Phylum Arthropoda, Class Crustacea, Subclass Malacostraca, and Order Amphipoda. The Malacostraca contains seventy percent of all known crustaceans. Over 10,000 species of amphipods are currently recognized. Twenty species of amphipods are known from Arkansas, with most being found in groundwater environments. Traditionally, amphipods have been placed in four suborders: the Caprellidea, Gammaridea, Hyperiidea, and Ingolfiellidea. The Gammaridea, which contains the majority of species, includes all the freshwater and semi-terrestrial taxa. The Hyperiidea includes the pelagic amphipods, which are associated with other planktonic forms such as gelatinous zooplankton (medusae and ctenophores). Hyperiids are usually characterized by very large eyes, although some forms, like gammarideans, have normal-sized eyes. Hyperiid members are a polyphyletic group, and it is thought …

Annelids

aka: Segmented Worms
The phylum Annelida consists of over 22,000 living species of segmented worms. They include earthworms, leeches, and ragworms. Annelids are bilaterally symmetrical, triploblastic invertebrates that inhabit a wide diversity of habitats, including marine environments such as tidal zones, hydrothermal vents, lotic and lentic freshwater habitats, and moist terrestrial habitats. The term “Annelida” originated in 1802 from French naturalist, Jean-Baptiste Lamarck’s (1744‒1829), annélides. Several species of annelids can be found in Arkansas. The overall classification of the phylum is undergoing significant revisions and has not yet been stabilized completely. Phylogenomic and other molecular phylogenetic analyses have shown that taxonomic groupings previously based on morphology in many cases are invalid. The phylum was previously divided into three classes as follows: Polychaeta (marine, …

Apicomplexans

aka: Sporozoans
The protistan Phylum Apicomplexa (formerly Sporozoa) contains a tremendous variety of obligate intracellular parasites infecting many different organisms, including humans. As a group, these parasites are cosmopolitan in their range of infected hosts and geographic distribution. They include such diverse parasites as coccidians, cryptosporids, gregarines, haemosporoids, and piroplasms. All are united, not by their biology or life histories, but morphologically by the presence of a unique structure called an apical complex. The classification scheme that cites this structure has a practical purpose to sort this diversity in a functional manner that can: (1) be easily understood and, (2) serve a utilitarian purpose by non-specialists. However, the field of classifying Apicomplexa is in flux; indeed, its taxonomy has changed throughout the …

Arachnids

Arachnids belong to Chelicerata, one of four groups of living arthropods. The other three groups are Crustacea, Myriapoda (centipedes and millipedes), and Hexapoda (insects and relatives). There are eleven living arachnid orders, and Arkansas has representatives of five of these including Scorpiones (scorpions), Pseudoscorpiones (pseudoscorpions), Opiliones (harvestmen), Aranea (spiders), and Acari (mites). Overview of Arachnids Arachnid bodies are divided into two main regions called the prosoma (cephalothorax) and opisthosoma (abdomen). These regions have been subdivided in some groups (e.g., solifugids, scorpions). The prosoma holds six pairs of appendages. Unlike in all other arthropods, the first appendages in chelicerates are not sensory antennae but pincer-like mouthparts known as chelicerae (hence the subphylum name). Behind the chelicerae, there are two pedipalps that …

Arkansas Darter

aka: Etheostoma cragini
Arkansas darter (Etheostoma cragini) populations are scattered among some small, spring-fed tributaries of the Arkansas River basin in Colorado, Kansas, Oklahoma, Missouri, and Arkansas. This fish species is rare in Arkansas, being found only in a few spring runs in the Illinois River basin of Benton and Washington counties. The small streams occupied by Arkansas darters are characterized by slow current and silt substrates. The darters shelter in watercress and other aquatic plants, overhanging or flooded terrestrial vegetation, and even in the loose silt of the stream bottom. In some places, they have been observed to move down into larger streams, but this has not been so in Arkansas. They grow to a maximum size of around two inches and …

Arkansas Entomological Society

The Arkansas Entomological Society (AES) was founded in May 1991 by entomology educators, researchers, and industry professionals under the guidance of Dr. William Yearian, former chair of the Entomology Department at the University of Arkansas (UA) in Fayetteville (Washington County). The first president of the society, Dr. Timothy Kring, drafted the society’s constitution with the purpose of fostering entomological accomplishment among its members as well as bringing about closer coordination and understanding among research, regulatory, educational, and commercial entomologists. Entomology is the study of insects and related organisms. Meetings of the society have been held annually since its founding, with locations and dates varying, but most often held on the first Friday and Saturday in October. Every other year, the …

Arkansas Fatmucket

aka: Lampsilis powellii
The Arkansas fatmucket is a bivalve mollusk belonging to the family Unionidae, commonly referred to as freshwater mussels, naiads, or clams. Each freshwater mussel is composed to two halves (valves) of a hard outer shell, with the living animal (soft tissues) residing securely inside. The Arkansas fatmucket (Lampsilis powellii) was described as a species new to science in 1852 by Isaac Lea, a naturalist and publisher by trade residing in Philadelphia, Pennsylvania. Lea based his description on specimens provided to him by Dr. Josiah Hale and Professor W. Byrd Powell from the Saline River at Benton (Saline County). Adults rarely reach a length of four inches (100 millimeters), and males and females are sexually dimorphic—that is, they have slightly different …

Atherinopsids

aka: Neotropical Silversides
Atherinopsids, or neotropical silversides, belong to the order Atheriniformes and family Atherinopidae. There are about 104 species within thirteen genera found in euryhaline, marine, and freshwater habitats distributed throughout the tropical and temperate waters of the Western Hemisphere. Three well-known atherinopsid fishes are the Atlantic silverside (Menidia menidia), California grunion (Leuresthes tenuis), and Gulf grunion (L. sardina). There are three species in Arkansas: the brook silverside (Labidesthes sicculus), golden silverside (L. vanhyningi), and Mississippi silverside (Menidia audens). Prior to the Neogene Period of the late Tertiary Period (66 to 2.5 million years ago), there is no fossil record of atherinopsids in North America. However, on San Francisco Bay, important prehistoric intertidal fisheries were especially well documented for atherinopsids. Silversides are …

Audubon Arkansas

Audubon Arkansas was established in 2000 as the twenty-fifth state office of the National Audubon Society through a seed grant from the Winthrop Rockefeller Charitable Trust. Audubon Arkansas’s mission is to inspire and lead Arkansans in environmental education, resource management, habitat restoration, bird conservation, and enlightened advocacy. In 2003, Audubon Arkansas was recognized as “Conservation Organization of the Year” by the Arkansas Wildlife Federation. Robert Shults was the founding board chairman of Audubon Arkansas. Shults, an Arkansan, served on the National Audubon Society board of directors from 1980 to 1986. The chairman of the National Audubon Society at the time was Donal C. O’Brien. O’Brien and Shults both served on the board of trustees of the Winthrop Rockefeller Charitable Trust. …

Audubon, John James

John James Audubon, a frontier naturalist and artist, is famous for illustrating and writing The Birds of America. He visited Arkansas Territory in 1820 and 1822 and documented Arkansas’s birds, including the Traill’s flycatcher, also known as the willow flycatcher, which is the only bird originally discovered in Arkansas. John Audubon was born Jean Rabin on April 26, 1785, in Saint-Domingue (Haiti). He was the illegitimate child of Jean Audubon, a ship’s captain, and Jeanne Rabin, a French chambermaid. His mother died in 1785 or 1786, and Jean Audubon and his children returned to France after a slave revolt. Along with his sister, he was adopted by his father and stepmother in 1794. Audubon stayed with his father and stepmother …

Bachman’s Warbler

aka: Vermivora bachmanii
Bachman’s warbler (Vermivora bachmanii) was a small, yellow-and-black bird of the American wood-warbler family (Parulidae) that formerly nested in the southeastern United States, including Arkansas. In winter, Bachman’s warblers migrated south to spend the winter on the island of Cuba. Preferring swampy bottomland habitat, the species suffered severe population decline in the early twentieth century when that habitat began disappearing and is now believed by most ornithologists to be extinct. Bachman’s warbler was discovered in 1832 near Charleston, South Carolina, by the Reverend John Bachman, a skilled amateur naturalist. Bachman (pronounced BACKman) was a close friend to John James Audubon, the famed naturalist and artist. Audubon painted a pair of the birds based on skins (prepared specimens) and named the …

Baerg, William J.

William J. Baerg was a naturalist, entomologist, and teacher who served as head of the Department of Entomology at the University of Arkansas (UA) in Fayetteville (Washington County) for thirty-one years. His research on black widow spiders, tarantulas, scorpions, and other arthropods led to descriptions of their behavior, biology, and natural history that had previously been largely ignored by biologists and entomologists. William Baerg was born in Hillsboro, Kansas, to Johann and Magaretha (Hildebrand) Baerg on September 24, 1885. His parents, who had left Russia in 1874, worked as field hands on a Kansas wheat farm. The family later acquired a small piece of land for their own. Baerg was the sixth of seven children. Baerg began school at age seven. At …

Banded Pygmy Sunfish

The banded pygmy sunfish (Elassoma zonatum) belongs to its own family (Elassomatidae) and the Order Perciformes. It is a diminutive sunfish that is about 25 to 40 mm (1.0 to 1.5 in.) in total length. This fish is endemic to the United States, where it ranges in the Mississippi River drainage from Indiana and Illinois south to Texas and east along the Atlantic Coast from North Carolina south to Florida. There are six additional species of Elassoma, including spring pygmy sunfish (E. alabamae), Carolina pygmy sunfish (E. boehlkei), Everglades pygmy sunfish (E. evergladei), Gulf Coast pygmy sunfish (E. gilberti), bluebarred pygmy sunfish (E. okatie), and Okefenokee pygmy sunfish (E. okefenokee). Interestingly, E. zonatum was described by the “Father of American …

Bats

Bats belong to the class Mammalia and the order Chiroptera. There are two suborders: the Yinpterochiroptera (formerly Megachiroptera), which includes the horseshoe and Old World fruit bats (megabats), and the Yangochiroptera (formerly Microchiroptera), the remainder of bats. Worldwide, there are eighteen families, 202 genera, and more than 1,100 species of bats with only about four percent (at least forty-five species) occurring in the United States. This mammalian order is second only in number of species behind the rodents (order Rodentia). Sixteen bat species occur in Arkansas. Much of the past research on bats in Arkansas was conducted by Michael J. (Mick) Harvey (1934–2015) of Tennessee Technical University in Cookeville. His research on several endangered bats in Arkansas was instrumental in …

Big Arkie

Big Arkie was a thirteen-foot-long alligator caught in 1952 near Hope (Hempstead County). He was the Little Rock Zoo’s main attraction for eighteen years. Weighing 500 pounds, Big Arkie was considered to be the largest alligator in captivity in the western hemisphere. Big Arkie was spied by a young boy in a flooded pasture by Yellow Creek, which is west of Hope. Ed Jackson, caretaker of a local hunting club, was alerted and, with some companions, wrapped Big Arkie in a fifty-foot-long cable attached to a tractor. The alligator spent one night in Hope’s public children’s pool, encased in chicken wire. On the following day, he was delivered to the Little Rock Zoo, doubled up in a crate. When the …

Birds

The birdlife of Arkansas (its avifauna) comprises just over 400 species, although that number includes more than forty species that have been extirpated (that is, they no longer occur) in the state, are completely extinct, or are rarities that have strayed into Arkansas fewer than a half dozen times. Around 350 species, then, can be found in Arkansas with some regularity. About 145 species nest within the state. Others nest north of Arkansas and spend the winter here or pass through the state in spring and fall as they migrate to and from nesting grounds to the north and wintering areas to the south. Arkansas’s location in the south-central United States means that its avifauna is generally typical of North …

Birdwatching

aka: Birding
Birdwatching, also commonly called birding, is the hobby of observing wild birds. Involvement in the pursuit ranges from enjoying birds on backyard feeders to traveling thousands of miles, nationally or internationally, to see new and different species. Birdwatching is usually considered to be distinct from ornithology, which is the scientific study of birds, although there is considerable overlap between the two. Birdwatchers often keep records of when and where they saw different species. Many people keep records simply for the personal satisfaction of remembering interesting and unusual sightings. Records kept by amateur birdwatchers, however, have made significant contributions to ornithology by helping with the knowledge of bird distribution and abundance. Most birdwatchers keep a life list—a record of all the …

Black Bears

aka: Ursus americanus
Black bears have a rich and varied history in Arkansas. Once giving to the state its unofficial nickname (the “Bear State”), bruins long shaped society and culture in Arkansas and continue to do so. Used for meat, fur, and fat, bears were a valuable commodity in the colonial period. By the early nineteenth century, although bears were still prized for their original uses, the bear-human relationship began to shift toward overt exploitation and bear hunting as a quest for masculine identity. By the first decades of the twentieth century, Arkansas black bears were at the brink of extirpation, but the population has since been revived. Native Americans were the first to hunt black bears in the region. Documented evidence of …

Bowfin

aka: Grinnell
Bowfin (Amia calva) belong to the primitive North American fish family Amiidae and Order Amiiformes. The family is monotypic and contains a single genus and species (A. calva). Bowfin are basal bony fishes related to gars in the infraclass Holostei. They are native to North America and are commonly found throughout much of the eastern United States, the St. Lawrence River, and Lake Champlain drainages of southern Ontario, and Quebec, Canada. Their range extends farther westward around the Great Lakes into Minnesota and south to the Colorado River in Texas. In Arkansas, A. calva is found in all major river drainages of the Gulf Coastal Plain lowlands and westward through the Arkansas River Valley; they are rarely found in the …

Branchiobdellidans

aka: Crayfish Worms
Branchiobdellidans, or crayfish worms, are leech-like, clitellate annelids belonging to the Phylum Annelida and Order Brachiobdellida (single family Brachiobdellidae) that form an obligate, ectosymbiotic association primarily with astacoidean crayfishes. They have long been known as “branchiobdellid worms” because they were considered a separate family of the oligochaetes; however, more recent treatment of these worms as a separate taxonomic order technically renders their epithet more correctly as “branchiobdellidan worms” or simply “branchiobdellidans.” Branchiobdellidans are a monophyletic clade of more than 150 ectosymbiont species within twenty-one genera found throughout North and Central America, Europe, and eastern Asia, of which about fifteen genera and 107 species have been reported from North America, including in Arkansas. However, branchiobdellid fauna in Arkansas need further study. …

Bryozoans

aka: Ectoprocta
aka: Moss Animals
Bryozoans (commonly called moss animals) are generally sessile, colonial invertebrates that belong to the phylum Bryozoa (or Ectoprocta), which is sometimes combined with two other phyla (Phoronida and Brachiopoda) to form a possible clade within the Deuterostomia. The three are sometimes referred to as the Lophophorata. Fossil bryozoans commonly found in Arkansas can be divided into two broad groups: the lacy colonies and the twig-shaped colonies. One fossil, the Archimedes, is especially abundant in northwestern Arkansas. In the southeastern United States, large gelatinous colonies of P. magnifica are a common sight, sometimes called “dinosaur snot.” These are often seen at Lake Wilhelmina in Polk County, and some have been reported in eastern Arkansas County. The primary uniting characteristic of this …

Butterflies and Moths

Arkansas has long been an ideal place to see butterflies and moths, but an increase in public awareness has occurred since the mid-1990s with the publication of scientific papers and checklists, as well as the emergence of special events in state parks. Butterflies and moths are classified in the insect order Lepidoptera, meaning “scale-wing.” Of approximately 350,000 species of butterflies and moths on earth, approximately 15,000 species are butterflies. Butterflies are distinguished from moths by the thousands of microscopic scales that create the color patterns on both sides of the wings. During a typical year, 134 butterfly species may be sighted in Arkansas, including year-round residents, summer residents, and migrants; 94 of these species live on Mount Magazine. An estimated …

Caddisflies

aka: Trichopterans
Caddisflies (Phylum Arthropoda, Class Insecta, Order Trichoptera) make up the largest and most diverse group of aquatic insects. More specifically, caddisflies are a group of small to medium-sized (2 to 30 mm in length), moth-like insects with two pairs of hairy membranous wings; they have aquatic larval forms that metamorphose into terrestrial adults. The name for the order Trichoptera comes from the name Trichos, which means “hairy,” and ptera, which means “wings.” The word “caddis” dates back to The Compleat Angler, written by Izaak Walton (1594–1683) and published in 1653, in which “cod-worms or caddis” were named as being used for bait. Caddisflies are a favorite food of many fish, and therefore are attractive to anglers, particularly trout fly fishermen, …

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 …

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 …

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 …

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. …