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Claw
A claw is a curved, pointed appendage found at the end of a toe or finger in most amniotes (mammals, reptiles, birds). Some invertebrates such as beetles and spiders have somewhat similar fine, hooked structures at the end of the leg or tarsus for gripping a surface as they walk. The pincers of crabs, lobsters and scorpions, more formally known as their chelae, are sometimes called claws. A true claw is made of a hard protein called keratin. Claws are used to catch and hold prey in carnivorous mammals such as cats and dogs, but may also be used for such purposes as digging, climbing trees, self-defense and grooming, in those and other species. Similar appendages that are flat and do not come to a sharp point are called nails instead. Claw-like projections that do not form at the end of digits but spring from other parts of the foot are properly named spurs. Tetrapods In tetrapods, claws are made of keratin and consist of two layers. The unguis is the harder external layer, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dewclaw
A dewclaw is a digit – vestigial in some animals – on the foot of many mammals, birds, and reptiles (including some extinct orders, like certain theropods). It commonly grows higher on the leg than the rest of the foot, such that in digitigrade or unguligrade species it does not make contact with the ground when the animal is standing. The name refers to the dewclaw's alleged tendency to brush dew away from the grass.Danziger, D., & McCrum, M. (2008). ''The Thingummy: A book about those everyday objects you just can't name''. London: Doubleday. On dogs and cats the dewclaws are on the inside of the front legs, similarly to a human's thumb, which shares evolutionary homology. Although many animals have dewclaws, other similar species do not, such as horses, giraffes and the African wild dog. Dogs Dogs almost always have dewclaws on the inside of the front legs and occasionally also on the hind legs. Unlike front dewclaws, rear dewclaws tend to have little bone or musc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crabs
Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the world's oceans, in freshwater, and on land, are generally covered with a thick exoskeleton, and have a single pair of pincers. They first appeared during the Jurassic Period. Description Crabs are generally covered with a thick exoskeleton, composed primarily of highly mineralized chitin, and armed with a pair of chelae (claws). Crabs vary in size from the pea crab, a few millimeters wide, to the Japanese spider crab, with a leg span up to . Several other groups of crustaceans with similar appearances – such as king crabs and porcelain crabs – are not true crabs, but have evolved features similar to true crabs through a process known as carcinisation. Environment Crabs are found in all of the world's oceans, as well as in fresh w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nail (anatomy)
A nail is a claw-like plate found at the tip of the fingers and toes on most primates. Nails correspond to the claws found in other animals. Fingernails and toenails are made of a tough protective protein called alpha-keratin, which is a polymer. Alpha-keratin is found in the hooves, claws, and horns of vertebrates. Structure The nail consists of the nail plate, the nail matrix and the nail bed below it, and the grooves surrounding it. Parts of the nail The matrix, sometimes called the ''matrix unguis'', keratogenous membrane, nail matrix, or onychostroma, is the active tissue (or germinal matrix) that generates cells, which harden as they move outward from the nail root to the nail plate. It is the part of the nail bed that is beneath the nail and contains nerves, lymph and blood vessels. The matrix produces cells that become the nail plate. The width and thickness of the nail plate is determined by the size, length, and thickness of the matrix, while the shape of the fing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cat Claw Closeup
The cat (''Felis catus'') is a domestic species of small carnivorous mammal. It is the only domesticated species in the family Felidae and is commonly referred to as the domestic cat or house cat to distinguish it from the wild members of the family. Cats are commonly kept as house pets but can also be farm cats or feral cats; the feral cat ranges freely and avoids human contact. Domestic cats are valued by humans for companionship and their ability to kill rodents. About 60 cat breeds are recognized by various cat registries. The cat is similar in anatomy to the other felid species: they have a strong flexible body, quick reflexes, sharp teeth, and retractable claws adapted to killing small prey. Their night vision and sense of smell are well developed. Cat communication includes vocalizations like meowing, purring, trilling, hissing, growling, and grunting as well as cat-specific body language. Although the cat is a social species, they are a solitary hunter. As a pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Predator
Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the host) and parasitoidism (which always does, eventually). It is distinct from scavenging on dead prey, though many predators also scavenge; it overlaps with herbivory, as seed predators and destructive frugivores are predators. Predators may actively search for or pursue prey or wait for it, often concealed. When prey is detected, the predator assesses whether to attack it. This may involve ambush or pursuit predation, sometimes after stalking the prey. If the attack is successful, the predator kills the prey, removes any inedible parts like the shell or spines, and eats it. Predators are adapted and often highly specialized for hunting, with acute senses such as vision, hearing, or smell. Many predatory animals, both vertebrate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pangolin
Pangolins, sometimes known as scaly anteaters, are mammals of the order Pholidota (, from Ancient Greek ϕολιδωτός – "clad in scales"). The one extant family, the Manidae, has three genera: '' Manis'', ''Phataginus'', and '' Smutsia''. ''Manis'' comprises the four species found in Asia, while ''Phataginus'' and ''Smutsia'' include two species each, all found in sub-Saharan Africa. These species range in size from . A number of extinct pangolin species are also known. Pangolins have large, protective keratin scales, similar in material to fingernails and toenails, covering their skin; they are the only known mammals with this feature. They live in hollow trees or burrows, depending on the species. Pangolins are nocturnal, and their diet consists of mainly ants and termites, which they capture using their long tongues. They tend to be solitary animals, meeting only to mate and produce a litter of one to three offspring, which they raise for about two years. Pangoli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scorpions
Scorpions are predatory arachnids of the order Scorpiones. They have eight legs, and are easily recognized by a pair of grasping pincers and a narrow, segmented tail, often carried in a characteristic forward curve over the back and always ending with a stinger. The evolutionary history of scorpions goes back 435 million years. They mainly live in deserts but have adapted to a wide range of environmental conditions, and can be found on all continents except Antarctica. There are over 2,500 described species, with 22 extant (living) families recognized to date. Their taxonomy is being revised to account for 21st-century genomic studies. Scorpions primarily prey on insects and other invertebrates, but some species hunt vertebrates. They use their pincers to restrain and kill prey, or to prevent their own predation. The venomous sting is used for offense and defense. During courtship, the male and female grasp each other's pincers and dance while he tries to move her onto his sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lobsters
Lobsters are a family (Nephropidae, synonym Homaridae) of marine crustaceans. They have long bodies with muscular tails and live in crevices or burrows on the sea floor. Three of their five pairs of legs have claws, including the first pair, which are usually much larger than the others. Highly prized as seafood, lobsters are economically important and are often one of the most profitable commodities in coastal areas they populate. Commercially important species include two species of '' Homarus'' from the northern Atlantic Ocean and scampi (which look more like a shrimp, or a "mini lobster")—the Northern Hemisphere genus '' Nephrops'' and the Southern Hemisphere genus '' Metanephrops''. Distinction Although several other groups of crustaceans have the word "lobster" in their names, the unqualified term "lobster" generally refers to the clawed lobsters of the family Nephropidae. Clawed lobsters are not closely related to spiny lobsters or slipper lobsters, which have no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cats
The cat (''Felis catus'') is a domestic species of small carnivorous mammal. It is the only domesticated species in the family Felidae and is commonly referred to as the domestic cat or house cat to distinguish it from the wild members of the family. Cats are commonly kept as house pets but can also be farm cats or feral cats; the feral cat ranges freely and avoids human contact. Domestic cats are valued by humans for companionship and their ability to kill rodents. About 60 cat breeds are recognized by various cat registries. The cat is similar in anatomy to the other felid species: they have a strong flexible body, quick reflexes, sharp teeth, and retractable claws adapted to killing small prey. Their night vision and sense of smell are well developed. Cat communication includes vocalizations like meowing, purring, trilling, hissing, growling, and grunting as well as cat-specific body language. Although the cat is a social species, they are a solitary hunter. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mammals
Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or hair, and three middle ear bones. These characteristics distinguish them from reptiles (including birds) from which they diverged in the Carboniferous, over 300 million years ago. Around 6,400 extant species of mammals have been described divided into 29 orders. The largest orders, in terms of number of species, are the rodents, bats, and Eulipotyphla ( hedgehogs, moles, shrews, and others). The next three are the Primates (including humans, apes, monkeys, and others), the Artiodactyla (cetaceans and even-toed ungulates), and the Carnivora ( cats, dogs, seals, and others). In terms of cladistics, which reflects evolutionary history, mammals are the only living members of the Synapsida (synapsids); this clade, together with S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthropod Leg
The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments (called podomeres) are of Latin origin, and may be confused with terms for bones: ''coxa'' (meaning hip, plural ''coxae''), ''trochanter'', ''femur'' (plural ''femora''), ''tibia'' (plural ''tibiae''), ''tarsus'' (plural ''tarsi''), ''ischium'' (plural ''ischia''), ''metatarsus'', ''carpus'', ''dactylus'' (meaning finger), ''patella'' (plural ''patellae''). Homologies of leg segments between groups are difficult to prove and are the source of much argument. Some authors posit up to eleven segments per leg for the most recent common ancestor of extant arthropods but modern arthropods have eight or fewer. It has been argued that the ancestral leg need not have been so complex, and that other events, such as successive loss of function of a ''Hox''-gene, could result in parallel gains of leg segments. In arthropods, each of the leg segments arti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrapod
Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids ( reptiles, including dinosaurs and therefore birds) and synapsids ( pelycosaurs, extinct therapsids and all extant mammals). Tetrapods evolved from a clade of primitive semiaquatic animals known as the Tetrapodomorpha which, in turn, evolved from ancient lobe-finned fish (sarcopterygians) around 390 million years ago in the Middle Devonian period; their forms were transitional between lobe-finned fishes and true four-limbed tetrapods. Limbed vertebrates (tetrapods in the broad sense of the word) are first known from Middle Devonian trackways, and body fossils became common near the end of the Late Devonian but these were all aquatic. The first crown-tetrapods ( last common ancestors of extant tetrapods capable of terrestrial locomotion) appeared by the very early Carboniferous, 350 million years ago. The specific aquat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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