The webbed foot is a specialized limb present in a variety of vertebrates to aid in locomotion. This adaptation is primarily found in semi-aquatic species, and has convergently evolved many times across vertebrate taxa. It likely arose from mutations in developmental genes that normally cause tissue between the digits to apoptose. These mutations were beneficial to many semi-aquatic animals because the increased surface area from the webbing allowed for more swimming propulsion and swimming efficiency, especially in surface swimmers. The webbed foot also has enabled other novel behaviors like escape responses and mating behaviors.
A webbed foot has connecting tissue between the toes of the foot. Several distinct conditions can give rise to webbed feet, including interdigital webbing and syndactyly. The webbing can consist of membrane, skin, or other connective tissue and varies widely in different taxa. This modification significantly increases the surface area of the feet. One of the consequences of this modification in some species, specifically birds, is that the feet are a major location for heat loss. In birds, the legs utilize countercurrent heat exchange so that blood reaching the feet is already cooled by blood returning to the heart to minimize this effect. Webbed feet take on a variety of different shapes; in birds, the webbing can even be discontinuous, as seen in lobate-footed birds like grebes. However, one of the most common is the delta (Δ) or triangular shape seen in most waterfowl and frogs. This delta wing shape is a solution that has convergently evolved in many taxa, and is also used in aircraft to allow for high lift forces at high attack angles. This shape allows for the production of large forces during swimming through both drag-based and lift-based propulsion.
Webbed feet are the result of mutations in genes that normally cause interdigital tissue between the toes to apoptose. Apoptosis, or programmed cell death, in development is mediated by a variety of pathways, and normally causes the creation of digits by death of tissue separating the digits. This process is mediated by a variety of pathways. Different vertebrate species with webbed feet have different mutations that disrupt this process, indicating that the structure arose independently in these lineages.
In humans, syndactyly can arise from as many as nine unique subtypes with their own clinical, morphological, and genetic fingerprints. In addition, the same genetic mutations can underlie different phenotypic expressions of syndactyly. While these conditions are disorders in humans, the variability in genetic cause of webbed digits informs our understanding of how this morphological change arose in species where webbed feet were selectifvely advantageous. These conditions also demonstrate a variety of genetic targets for mutation resulting in webbed feet, which may explain how this homologous structure could have arose many times over the course of evolutionary history. One pathway implicated in interdigital necrosis is the Bone morphogenetic protein (BMP) signaling pathway. BMP signaling molecules (BMPs) are expressed in the tissue regions between digits during development. In experiments with chickens, mutations to a BMP receptor disrupted the apoptosis of interdigital tissue and caused webbed feet similar to ducks to develop. In ducks, BMPs are not expressed at all. These results indicate that in avian lineages, the disruption of BMP signaling in interdigital tissue caused webbed feet to arise. The magnitude of attenuation in this pathway is correlated with the amount of interdigital tissue preserved. Other genetic changes implicated in webbed feet development in avians include reduction of TGFβ-induced chondrogenesis and reduction of msx-1 and msx-2 gene expression.
Webbed feet could also arise due to being linked to other morphological changes, without a selective advantage. In salamanders, webbed feet have arisen in multiple lineages, but in most do not contribute to increased function. However, in the cave salamander species Chiropterotriton magnipes (bigfoot splayfoot salamander), their webbed feet are morphologically unique from other salamanders and may serve a functional purpose. This demonstrates that webbed feet arise from developmental changes, but do not necessarily correlate with a selective advantage functionally.
Webbed feet have arisen in all major vertebrate lineages with limbed animals. Most webbed-footed species spend part of their time in aquatic environments, indicating that this homologous structure provides some advantage to swimmers. Some examples from each class are highlighted here, but this is not a complete listing.
Of the three orders of amphibians, Anura (frogs and toads) and Urodela (salamanders) have representative species with webbed feet. Frogs that live in aquatic environments, like the common frog (Rana temporaria), have webbed feet. Salamanders in arboreal and cave environments also have webbed feet, but in most species, this morphological change does not likely have a functional advantage.
Birds are typically classified as a sub-group of reptiles, but they are a distinct class within vertebrates, so are discussed separately. Birds have a wide span of representatives with webbed feet, due to the diversity of waterfowl. Ducks, geese, and swans all have webbed feet. They utilize different foraging behaviors in water, but use similar modes of locomotion. There is a wide variety of webbing and lobation styles in bird feet, including birds with all digits joined in webbing, like the Brandt's cormorant and birds with lobed digits, like grebes. Palmations and lobes enable swimming or help walking on loose ground such as mud. The webbed or palmated feet of birds can be categorized into several types:
The palmate foot is most common.
Some semi-aquatic mammals have webbed feet. Most of these have interdigital webbing, as opposed to the syndactyly found in birds. Some notable examples include the platypus, the beaver, the otter, and the water opossum.
In many species, webbed feet likely evolved to aid in generation of propulsion during swimming. Most webbed-footed animals utilize paddling modes of locomotion where their feet stroke backwards relative to their whole body motion, generating a propulsive force. The interdigital membrane increases the surface area, which increases the propulsive drag the animal can generate with each stroke of its foot. This is a drag-based mode of propulsion. However, some waterfowl also utilize lift-based modes of propulsion, where their feet generate hydrodynamic lift due to the angle of attack of the foot and the relative water velocity. For example, great-crested grebes use solely lift-based propulsion due to their lateral foot stroke and asymmetric, lobated toes. Most waterfowl use a combination of these two modes of propulsion, where the first third of their foot stroke generates propulsive drag and the last two-thirds of the stroke generates propulsive lift.
The stroke of the foot through the water also generates vortices that aid propulsion. During the transition from drag-based to lift-based propulsion in ducks, leading edge vortices formed on the front of the foot are shed, which creates a flow of water over the foot that likely aids lift production. Other species also create these vortices during their webbed foot stroke. Frogs also create vortices that shed off their feet when swimming in water. The vortices from the two feet do not interfere with each other; therefore, each foot is generating forward propulsion independently.
Most fully aquatic vertebrates do not use paddling modes of locomotion, instead using undulatory modes of locomotion or flipper locomotion. Fully aquatic mammals and animals typically have flippers instead of webbed feet, which are a more heavily specialized and modified limb. It is hypothesized that an evolutionary transition between semi-aquatic and fully aquatic higher vertebrates (especially mammals) involved both the specialization of swimming limbs and the transition to underwater, undulatory modes of motion. However, for semi-aquatic animals that mainly swim at the surface, webbed feet are highly functional; they trade-off effectively between efficient terrestrial and aquatic locomotion. In addition, some waterfowl can also use paddling modes for underwater swimming, with added propulsion from flapping their wings. Diving ducks can swim underwater to forage. These ducks expend more than 90% of their energy to overcome their own buoyancy when they dive. They can also achieve higher speeds underwater due to surface speeds being limited to their hull speed; at this speed, the wave drag increases to the point where the duck cannot swim faster.
In ducks, webbed feet have also enabled extreme forms of propulsion that are used for escape behaviors and courtship display. Surface swimmers are speed-limited due to increasing drag as they approach a physically-defined hull speed, which is determined by their body length. In order to achieve speeds higher than hull speed, some ducks, like eider ducks, use distinctive modes of locomotion that involve lifting the body out of the water. They can hydroplane, where they lift part of their body out of the water and paddle with their webbed feet to generate forces that allow them to overcome gravity; they also use paddle-assisted flying, where the whole body is lifted out of the water, and the wings and feet work in concert to generate lift forces. In extreme cases, this type of behavior is used for sexual selection. Western and Clark's grebes utilize their lobated feet to generate nearly 50% of the force required to allow them to walk on water in elaborate sexual displays. They are likely the largest animal to "walk" on water, and are an order of magnitude heavier than the well-known lizards that exhibit a similar behavior.
While webbed feet have mainly arisen in swimming species, they can also aid in terrestrial locomotors by increasing contact area on slick or soft surfaces. For P. rangei, the Namib sand gecko, their webbed feet may serve as sand shoes that enable them to move atop sand dunes. However, some ecologists believe that their webbed feet do not aid aboveground locomotion, but are mainly utilized as shovels for burrowing and digging in the sand. In salamanders, most species do not benefit from the increased surface area of their feet. However, some, like the bigfoot splayfoot salamander (Chiropterotriton magnipes) increase their body size to foot surface area ratio enough to provide increased suction. This species lives in cave environments where they often encounter wet, slick surfaces. Therefore, their webbed feet may enable them to move on these surfaces with ease.
The Anaheim Ducks are a professional ice hockey team based in Anaheim, California. They are members of the Pacific Division of the Western Conference of the National Hockey League (NHL). Since their inception, the Ducks have played their home games at the Honda Center (formerly The Arrowhead Pond of Anaheim).
The club was founded in 1993 by The Walt Disney Company as the Mighty Ducks of Anaheim, a name based on the 1992 film The Mighty Ducks. Disney sold the franchise in 2005 to Henry and Susan Samueli, who along with then-general manager Brian Burke changed the name of the team to the Anaheim Ducks before the 2006–07 season. The Ducks have made the playoffs 14 times (and 11 times in the past 13 seasons) and won six Pacific Division titles (2006–07, 2012–13, 2013–14, 2014–15, 2015–16 and 2016–17), two Western Conference championships (2002–03 and 2006–07) and one Stanley Cup (2006–07).Aporrhais pespelecani
Aporrhais pespelecani, common name the "pelican's foot" (or more precisely "common pelican's foot" to distinguish it from congeners), is a species of sea snail, a marine gastropod mollusk in the family Aporrhaidae.
Until the early 20th century the scientific name was usually written with a hyphen and spelled "pes-pelicani". Cagot
The Cagots (pronounced [ka.ɡo]) were a persecuted and despised minority found in the west of France and northern Spain: the Navarrese Pyrenees, Basque provinces, Béarn, Aragón, Gascony and Brittany. Their name has differed by province and the local language: Cagots, Gézitains, Gahets, and Gafets in Gascony; Agotes, Agotak, and Gafos in Basque country; Capots in Anjou and Languedoc; and Cacons, Cahets, Caqueux, and Caquins in Brittany. Evidence of the group exists back as far as AD 1000.Cagots were shunned and hated. While restrictions varied by time and place, they were typically required to live in separate quarters in towns, called cagoteries, which were often on the far outskirts of the villages. Cagots were excluded from all political and social rights. They were not allowed to marry non-Cagots, enter taverns, hold cabarets, use public fountains, sell food or wine, touch food in the market, work with livestock, or enter mills. They were allowed to enter a church only by a special door and, during the service, a rail separated them from the other worshippers. Either they were altogether forbidden to partake of the sacrament, or the Eucharist was given to them on the end of a wooden spoon, while a holy water stoup was reserved for their exclusive use. They were compelled to wear a distinctive dress to which, in some places, was attached the foot of a goose or duck (whence they were sometimes called "Canards"). So pestilential was their touch considered that it was a crime for them to walk the common road barefooted or to drink from the same cup as non-Cagots. The Cagots were often restricted to the trades of carpenter, butcher, and rope-maker.The Cagots were not an ethnic group, nor a religious group. They spoke the same language as the people in an area and generally kept the same religion as well. Their only distinguishing feature was their descent from families identified as Cagots. Few consistent reasons were given as to why they should be hated; accusations varied from Cagots being cretins, lepers, heretics, cannibals, to simply being intrinsically evil. The Cagots did have a culture of their own, but very little of it was written down or preserved; as a result, almost everything that is known about them relates to their persecution. Their cruel treatment lasted through the Middle Ages, Renaissance, and Industrial Revolution, with the prejudice fading only in the 19th and 20th centuries.Dorsal fin
A dorsal fin is a fin located on the back of most marine and freshwater vertebrates such as fishes, cetaceans (whales, dolphins, and porpoises), and the (extinct) ichthyosaur. Most species have only one dorsal fin, but some have two or three.
Wildlife biologists often use the distinctive nicks and wear patterns which develop on the dorsal fins of large cetaceans to identify individuals in the field.
The bony or cartilaginous bones that support the base of the dorsal fin in fish are called pterygiophores.Eastern mole
The eastern mole or common mole (Scalopus aquaticus) is a medium-sized, overall grey North American mole and the only member of the genus Scalopus. Its large, hairless, spade-shaped forefeet are adapted for digging. The species is native to Canada (Ontario), Mexico, and the eastern United States, and has the widest range of any North American mole.
The species prefers the loamy soils found in thin woods, fields, pastures, and meadows, and builds both deep and shallow burrows characterized by discarded excess soil collected in molehills. Its nest is composed of leaves and grasses, and its two to five young are on their own at about four weeks. Its diet consists principally of earthworms and other soil life, but the mole will eat vegetable matter.
Dogs, cats, foxes, and coyotes prey upon the mole, and the species hosts a variety of parasites. Unlike gophers, moles do not eat vegetation and pose no threat to human concerns; the occasional damage to lawns is offset by the aeration provided the soil and consumption of insects. The construction of golf courses has provided the mole with ideal habitat. The species is abundant, occurs in protected areas, faces no major threats and is of little concern to conservationists.Fin and flipper locomotion
Fin and flipper locomotion occurs mostly in aquatic locomotion, and rarely in terrestrial locomotion. From the three common states of matter — gas, liquid and solid, these appendages are adapted for liquids, mostly fresh or saltwater and used in locomotion, steering and balancing of the body. Locomotion is important in order to escape predators, acquire food, find mates and bury for shelter, nest or food. Aquatic locomotion consists of swimming, whereas terrestrial locomotion encompasses walking, 'crutching', jumping, digging as well as covering. Some animals such as sea turtles and mudskippers use these two environments for different purposes, for example using the land for nesting, and the sea to hunt for food.Fish fin
Fins are usually the most distinctive anatomical features of a fish. They are composed of bony spines or rays protruding from the body with skin covering them and joining them together, either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as seen in sharks. Apart from the tail or caudal fin, fish fins have no direct connection with the spine and are supported only by muscles. Their principal function is to help the fish swim. Fins located in different places on the fish serve different purposes such as moving forward, turning, keeping an upright position or stopping. Most fish use fins when swimming, flying fish use pectoral fins for gliding, and frogfish use them for crawling. Fins can also be used for other purposes; male sharks and mosquitofish use a modified fin to deliver sperm, thresher sharks use their caudal fin to stun prey, reef stonefish have spines in their dorsal fins that inject venom, anglerfish use the first spine of their dorsal fin like a fishing rod to lure prey, and triggerfish avoid predators by squeezing into coral crevices and using spines in their fins to lock themselves in place.Gerald of Wales
Gerald of Wales (Latin: Giraldus Cambrensis; Welsh: Gerallt Gymro; French: Gerald de Barri; c. 1146 – c. 1223) was a Cambro-Norman archdeacon of Brecon and historian. As a royal clerk to the king and two archbishops, he travelled widely and wrote extensively. He both studied and taught in France and visited Rome several times, meeting the Pope. He was nominated for several bishoprics but turned them down in the hope of becoming bishop of St Davids, but was unsuccessful despite considerable support. His final post was as archdeacon of Brecon, from which he retired to academic study for the remainder of his life. Much of his writing survives.La Carabina de Ambrosio
La Carabina de Ambrosio was a Mexican television show created and developed by Humberto Navarro, filmed at the Televisa Studios, Chapultepec in Mexico City, from 1978 until 1987. The slogan of the show was "A Magical, Comical, and Musical Variety Show." The show had guest emcees that included César Costa, Gualberto Castro, Fito Girón, and Manolo Muñoz. While the emcees sang a cast member would interrupt rudely and a comedy skit began. The show consisted of numerous skits, jokes and tricks played on the emcees. It is rumored that the reason there were so many emcees during the run of the show was due the numerous tricks played on them.
Since 2007, the show is in re-runs on TV Clásico.Long Island Ducks
The Long Island Ducks are an American professional baseball team based on Long Island in the Suffolk County town of Central Islip, New York. The Ducks compete in the Atlantic League of Professional Baseball (ALPB) as a member of the Liberty Division. The ALPB is an independent baseball league which is not affiliated with Major League Baseball. They are the only team in the league to be based in New York. The Long Island Ducks played their first season in 2000, two years after the Atlantic League of Professional Baseball played its inaugural season in 1998. The Ducks' home ballpark has been Bethpage Ballpark since their inception in 2000. Throughout its history, the stadium has formerly been known as Suffolk County Sports Park (1999), EAB Park (2000-2001), and Citibank Park (2002-2009). The "Ducks" name refers to Long Island's duck-farming heritage, which is further represented by the Big Duck ferrocement. The Big Duck is also located in Suffolk County in the hamlet of Flanders, New York.The Ducks set the independent league baseball single-season attendance record at the time by welcoming 443,142 fans during the 2001 season. This surpassed the previous record of 436,361 fans which the team had also set in 2000. The Ducks reached the 5 million fan mark in attendance in July 2011 and welcomed their Atlantic League record 6 millionth fan in mid-2014.
Bud Harrelson, a 1971 Rawlings Gold Glove Award winner, is a part-owner of the Ducks. He was the first manager of the team following a stint as the New York Mets manager.Martin Lockley
Martin Lockley (born 1950) is a Welsh palaeontologist. He was educated in the United Kingdom where he obtained degrees (BSc and PhD) and post-doctoral experience in Geology in the 1970s. Since 1980 he has been a professor at the University of Colorado at Denver, (UCD) and is currently a Professor Emeritus. He is best known for work on fossil footprints and was former director of the Dinosaur Tracks Museum at UCD. He is an Associate Curator at the University of Colorado Museum of Natural History and Research Associate at the Denver Museum of Nature and Science. During his years at UCD he earned a BA in 2007 in Spanish with a minor in Religious Studies, became a member of the Scientific and Medical Network and taught and published on the evolution of consciousness.Osprey
The osprey or more specifically the western osprey (Pandion haliaetus) — also called sea hawk, river hawk, and fish hawk — is a diurnal, fish-eating bird of prey with a cosmopolitan range. It is a large raptor, reaching more than 60 cm (24 in) in length and 180 cm (71 in) across the wings. It is brown on the upperparts and predominantly greyish on the head and underparts.
The osprey tolerates a wide variety of habitats, nesting in any location near a body of water providing an adequate food supply. It is found on all continents except Antarctica, although in South America it occurs only as a non-breeding migrant.
As its other common names suggest, the osprey's diet consists almost exclusively of fish. It possesses specialised physical characteristics and exhibits unique behaviour to assist in hunting and catching prey. As a result of these unique characteristics, it has been given its own taxonomic genus, Pandion and family, Pandionidae. Three subspecies are usually recognized; one of the former subspecies, cristatus, has recently been given full species status and is referred to as the eastern osprey.Rodgersia
Rodgersia is a genus of flowering plants in the Saxifragaceae family. Rodgersia are herbaceous perennials originating from east Asia.Rotating locomotion in living systems
Several organisms are capable of rolling locomotion; however, true wheels and propellers—despite their utility in human vehicles—do not appear to play a significant role in the movement of living things (with the exception of certain flagella, which function like corkscrews). Biologists have expounded on the reasons for this apparent absence of biological wheels, and wheeled creatures have appeared often in speculative fiction.
Given the ubiquity of the wheel in human technology, and the existence of biological analogues of many other technologies (such as wings and lenses), the lack of wheels in the natural world would seem to demand explanation—and the phenomenon is broadly explained by two main factors. First, there are several developmental and evolutionary obstacles to the advent of a wheel by natural selection, addressing the question "Why can't life evolve wheels?" Secondly, wheels are often at a competitive disadvantage when compared with other means of propulsion (such as walking, running, or slithering) in natural environments, addressing the question "If wheels could evolve, why might they be rare nonetheless?" This environment-specific disadvantage also explains why at least one historical civilization abandoned the wheel as a mode of transport.Webbed toes
Webbed toes is the common name for syndactyly affecting the feet. It is characterised by the fusion of two or more digits of the feet. This is normal in many birds, such as ducks; amphibians, such as frogs; and mammals, such as kangaroos. In humans it is considered unusual, occurring in approximately one in 2,000 to 2,500 live births. Most commonly the second and third toes are webbed or joined by skin and flexible tissue. This can reach either part way up or nearly all the way up the toe.