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An order of batoid fishes (subclass Elasmobranchii), the typical members of which are described by the following characteristics: The disc is strongly depressed and varies from oval longitudinally to much broader than long; the tail is well marked off from the body sector, very short to long and whiplike, and equipped with a poisonous spine in some species; the pectoral rays are either continuous along the side of the head or separate from the head and modified to form rostral lobes or finlike rostral appendages (cephalic fins); the dorsal fin, if present, is near the base of the tail; and development is ovoviviparous. Sometimes an individual ray may have two or three, very rarely four, tail spines rather than the usual one. Multiple spines result from the failure of older spines to shed before new ones develop. Most species are tropical or subtropical, although some species occur in warm temperate and cool temperate zones. The usual habitat is shallow shore waters and upper continental and insular slopes. Some, such as the eagle rays, may venture far out to sea, but none are considered truly oceanic rays.
Industry:Science
An order of batoid fishes occurring in the subclass Elasmobranchii and known as the torpedo electric rays and numbfishes. Typical members of Torpediniformes are identifiable by their flat, pancakelike body sector (disc); relatively robust tail sector; smooth skin; small or obsolete eyes; distinct caudal fin; and ovoviviparous development (that is, producing eggs that develop internally and hatch before or soon after extrusion). Of special interest is a pair of enlarged electric organs located on the disc lateral to the gill slits. These kidney-shaped organs can best be seen from the ventral side, although the columnar structures that compose them occupy the thickness of the disc. These electric organs, which may constitute 17% of the total body weight, deliver shocks up to 220 volts. The voltage depends on the species, its size, and physical condition. The electric organs are thought to be used primarily for feeding and defense. Electric rays are poor swimmers, depending primarily on the tail because the disc is rather inflexible and of little use in locomotion, although it is flexible enough for capturing prey. They spend most of their time partially buried in sand or mud and feed on a variety of invertebrates, including crustaceans, mollusks, and worms, as well as small fishes. Members of the genus <i>Torpedo</i> are reported to reach a length of 1.8 m (6 ft) and a weight of 44 kg (100 lb). Torpediniforms occur in intertidal waters to deep waters (1070 m or 3510 ft in the case of blind species (<i>Benthobatis</i>)) in temperate to tropical zones of all oceans.
Industry:Science
An order of birds comprising two families, the screamers (Anhimidae) of South America and the worldwide waterfowl (Anatidae). They are closely related to the Galliformes (fowls), with the screamers being a rather intermediate group. The waterfowl and the fowls are closely related within the Aves and are often placed within a distinct superorder, the Galloanserae. The large, flightless diatrymids (giant ground birds) of the early Tertiary appear to be specialized offshoots of the Anseriformes.
Industry:Science
An order of birds consisting of two dissimilar groups, the swifts (Apodi) and the hummingbirds (Trochili). These birds have been placed together because of several anatomical specializations of the wings and feathers, although an alternative classification based on morphological and molecular characters places the swifts and hummingbirds in two separate orders. Swifts and hummingbirds have strong wings and are excellent fliers but have small, weak feet and cannot walk. Some of these features may be convergences because of the rapid but different flight of these birds. The two groups share a unique crossover structure of a superficial neck muscle which cannot be related to their ways of life. The relationship of the swifts and hummingbirds to other birds is obscure.
Industry:Science
An order of birds containing the family Columbidae (worldwide; true pigeons and doves) and two smaller related families. The members of this order are characterized by an ability to drink water by “sucking” (actually lapping using the tongue) instead of the sip-and-tilt method of most birds. However, some other groups of birds are able to “suck” water by various methods.
Industry:Science
An order of birds having zygodactyl feet (two toes are in front and two behind) in which the fourth toe is reversed, but not having any close relationship to other birds with this foot structure, such as the parrots or piciforms. The relationship of the touracos to the cuckoos has been strongly debated and is still unresolved. However, this conclusion is very controversial because the hoatzin possesses an anisodactyl pattern of the toes (three toes are in front and one is in back); thus, many authors still place the hoatzin in its own order next to the Cuculiformes.
Industry:Science
An order of bivalves in subclass Lamellibranchia whose hinge dentition is characterized by a series of numerous similar alternating teeth and sockets. Typical genera of so-called ark shells are <i>Arca</i>, <i>Barbatia</i>, and <i>Anadara</i>, all with heavy coarse or matted periostracum, and mostly with strong radial ribs on globose or purse-shaped shells. The filibranch gills are enlarged to form the four double lamellae of the filter-feeding organs as in all true lamellibranchs, and the labial palps form complex sorting surfaces.
Industry:Science
An order of branchiopod crustaceans, sometimes called tadpole shrimps. Generally they range from about 20 mm (0.4 in.) to (exceptionally) about 90 mm (3.5 in.) in length. The multisegmented trunk, up to 44 segments in some species, is elongate and cylindrical. The anterior part of the body is covered dorsally by a domed carapace beneath which lie the paired sessile eyes. Each of the first 11 trunk segments bears a pair of limbs, while a varying number of more posterior segments bear up to six pairs of smaller limbs per segment—a very unusual situation. At least four, often more, posterior segments are limbless. The trunk terminates in a telson that bears a pair of slender, segmented, caudal filaments. Each trunk limb bears several endites. These are mostly used for handling the food and become progressively reduced on the smaller posterior limbs, but are drawn out into long, filiform sensory structures on the first pair. In the female, the eleventh pair bears a bowl-shaped pouch with a hinged lid that acts as a temporary receptacle for the eggs that are then shed, or are stuck to surfaces.
Industry:Science
An order of bryozoans in the class Stenolaemata. Cyclostomes tend to have delicate colonies composed of relatively isolated, loosely bundled or tightly packed, comparatively simple, long, slender, and tubular zooecia (individual living chambers), with thin, highly porous, calcareous walls. When regionated, their colonies display a very gradual transition between rather indistinct endozones and exozones.
Industry:Science
An order of carnivorous branchiopod crustaceans formerly included in the order Cladocera. Only one species, the fresh-water <i>Leptodora kindti</i>, is included.
Industry:Science
