Reptile
Reptiles are tetrapod animals in the class Reptilia, comprising today's turtles, snakes, lizards and their extinct relatives. The study of these traditional reptile orders combined with that of modern amphibians, is called herpetology; because some reptiles are more related to birds than they are to other reptiles, the traditional groups of "reptiles" listed above do not together constitute a monophyletic grouping or clade. For this reason, many modern scientists prefer to consider the birds part of Reptilia as well, thereby making Reptilia a monophyletic class, including all living Diapsids; the earliest known proto-reptiles originated around 312 million years ago during the Carboniferous period, having evolved from advanced reptiliomorph tetrapods that became adapted to life on dry land. Some early examples include Casineria. In addition to the living reptiles, there are many diverse groups that are now extinct, in some cases due to mass extinction events. In particular, the Cretaceous–Paleogene extinction event wiped out the pterosaurs, plesiosaurs and sauropods, as well as many species of theropods, including troodontids, dromaeosaurids and abelisaurids, along with many Crocodyliformes, squamates.
Modern non-avian reptiles inhabit all the continents except Antarctica, although some birds are found on the periphery of Antarctica. Several living subgroups are recognized: Testudines, 350 species. Reptiles are tetrapod vertebrates, creatures that either have four limbs or, like snakes, are descended from four-limbed ancestors. Unlike amphibians, reptiles do not have an aquatic larval stage. Most reptiles are oviparous, although several species of squamates are viviparous, as were some extinct aquatic clades – the fetus develops within the mother, contained in a placenta rather than an eggshell; as amniotes, reptile eggs are surrounded by membranes for protection and transport, which adapt them to reproduction on dry land. Many of the viviparous species feed their fetuses through various forms of placenta analogous to those of mammals, with some providing initial care for their hatchlings. Extant reptiles range in size from a tiny gecko, Sphaerodactylus ariasae, which can grow up to 17 mm to the saltwater crocodile, Crocodylus porosus, which can reach 6 m in length and weigh over 1,000 kg.
In the 13th century the category of reptile was recognized in Europe as consisting of a miscellany of egg-laying creatures, including "snakes, various fantastic monsters, assorted amphibians, worms", as recorded by Vincent of Beauvais in his Mirror of Nature. In the 18th century, the reptiles were, from the outset of classification, grouped with the amphibians. Linnaeus, working from species-poor Sweden, where the common adder and grass snake are found hunting in water, included all reptiles and amphibians in class "III – Amphibia" in his Systema Naturæ; the terms "reptile" and "amphibian" were interchangeable, "reptile" being preferred by the French. Josephus Nicolaus Laurenti was the first to formally use the term "Reptilia" for an expanded selection of reptiles and amphibians similar to that of Linnaeus. Today, the two groups are still treated under the same heading as herptiles, it was not until the beginning of the 19th century that it became clear that reptiles and amphibians are, in fact, quite different animals, Pierre André Latreille erected the class Batracia for the latter, dividing the tetrapods into the four familiar classes of reptiles, amphibians and mammals.
The British anatomist Thomas Henry Huxley made Latreille's definition popular and, together with Richard Owen, expanded Reptilia to include the various fossil "antediluvian monsters", including dinosaurs and the mammal-like Dicynodon he helped describe. This was not the only possible classification scheme: In the Hunterian lectures delivered at the Royal College of Surgeons in 1863, Huxley grouped the vertebrates into mammals and ichthyoids, he subsequently proposed the names of Ichthyopsida for the latter two groups. In 1866, Haeckel demonstrated that vertebrates could be divided based on their reproductive strategies, that reptiles and mammals were united by the amniotic egg; the terms "Sauropsida" and "Theropsida" were used again in 1916 by E. S. Goodrich to distinguish between lizards and their relatives on the one hand and mammals and their extinct relatives on the other. Goodrich supported this division by the nature of the hearts and blood vessels in each group, other features, such as the structure of the forebrain.
According to Goodrich, both lineages evolved from an earlier stem group, Protosauria in which he included some animals today considered reptile-like amphibians, as well as early reptiles. In 1956, D. M. S. Watson observed that the first two groups diverged early in reptilian history, so he divided Goodrich's Protosauria between them, he reinterpreted Sauropsida and Theropsida to exclude birds and mammals, respectively. Thus his Sauropsida included Procolophonia, Millerosauria, Squamata, Rhynchocephalia
Wolf
The wolf known as the grey/gray wolf or timber wolf, is a canine native to the wilderness and remote areas of Eurasia and North America. It is the largest extant member of its family, with males averaging 43 -- females 36 -- 38.5 kg. It is distinguished from other Canis species by its larger size and less pointed features on the ears and muzzle, its winter fur is long and bushy and predominantly a mottled gray in color, although nearly pure white and brown to black occur. Mammal Species of the World, a standard reference work in zoology, recognises 38 subspecies of C. lupus. The gray wolf is the second most specialized member of the genus Canis, after the Ethiopian wolf, as demonstrated by its morphological adaptations to hunting large prey, its more gregarious nature, its advanced expressive behavior, it is nonetheless related enough to smaller Canis species, such as the coyote, golden jackal, to produce fertile hybrids. It is the only species of Canis to have a range encompassing both Eurasia and North America, originated in Eurasia during the Pleistocene, colonizing North America on at least three separate occasions during the Rancholabrean.
It is a social animal, travelling in nuclear families consisting of a mated pair, accompanied by the pair's adult offspring. The gray wolf is an apex predator throughout its range, with only humans and tigers posing a serious threat to it, it feeds on large ungulates, though it eats smaller animals, livestock and garbage. A seven-year-old wolf is considered to be old, the maximum lifespan is about 16 years; the global gray wolf population is estimated to be 300,000. The gray wolf is one of the world's best-known and most-researched animals, with more books written about it than any other wildlife species, it has a long history of association with humans, having been despised and hunted in most pastoral communities because of its attacks on livestock, while conversely being respected in some agrarian and hunter-gatherer societies. Although the fear of wolves is pervasive in many human societies, the majority of recorded attacks on people have been attributed to animals suffering from rabies. Non-rabid wolves have attacked and killed people children, but this is rare, as wolves are few, live away from people, have developed a fear of humans from hunters and shepherds.
The English'wolf' stems from the Old English wulf, itself thought to be derived from the Proto-Germanic *wulfaz. The Latin lupus is a Sabine loanword. Both derive from the Proto-Indo-European root * lukwos; the species Canis lupus was first recorded by Carl Linnaeus in his publication Systema Naturae in 1758, with the Latin classification translating into the English words "dog wolf". The 37 subspecies of Canis lupus are listed under the designated common name of "wolf" in Mammal Species of the World, published in 2005; the nominate subspecies is the Eurasian wolf known as the common wolf. The subspecies includes the domestic dog, eastern wolf and red wolf, but lists C. l. italicus as a synonym of C. l. lupus. However, the classification of several as either species or subspecies has been challenged; the evolution of the wolf occurred over a geologic time scale of at least 300,000 years. The gray wolf Canis lupus is a adaptable species, able to exist in a range of environments and which possesses a wide distribution across the Holarctic.
Studies of modern gray wolves have identified distinct sub-populations that live in close proximity to each other. This variation in sub-populations is linked to differences in habitat – precipitation, temperature and prey specialization – which affect cranio-dental plasticity; the archaeological and paleontological records show gray wolf continuous presence for at least the last 300,000 years. This continuous presence contrasts with genomic analyses, which suggest that all modern wolves and dogs descend from a common ancestral wolf population that existed as as 20,000 years ago; these analyses indicate a population bottleneck, followed by a rapid radiation from an ancestral population at a time during, or just after, the Last Glacial Maximum. However, the geographic origin of this radiation is not known. In 2018, whole genome sequencing was used to compare members of the genus Canis, along with the dhole and the African hunting dog. There is evidence of gene flow between African golden wolves, golden jackals, gray wolves.
One African golden wolf from the Egyptian Sinai Peninsula showed high admixture with the Middle Eastern gray wolves and dogs, highlighting the role of the land bridge between the African and Eurasian continents in canid evolution. There was evidence of gene flow between golden jackals and Middle Eastern wolves, less so with European and Asian wolves, least with North American wolves; the study proposes that the golden jackal ancestry found in North American wolves may have occurred before the divergence of the Eurasian and North American gray wolves. The study indicates that the common ancestor of the coyote and gray wolf has genetically admixed with a ghost population of an extinct unidentified canid; the canid is genetically close to the dhole and has evolved after the divergence of the African hunting dog from the other canid species. The basal position of the coyote compared to the wolf is proposed to be due to the coyote retaining more of the mitochondrial genome of this unknown canid.
In 2013, a genetic study found that the wolf population in Europe was divided along a north-south axis and formed five major clusters. Three clusters were identified occupying southern and
Biology
Biology is the natural science that studies life and living organisms, including their physical structure, chemical processes, molecular interactions, physiological mechanisms and evolution. Despite the complexity of the science, there are certain unifying concepts that consolidate it into a single, coherent field. Biology recognizes the cell as the basic unit of life, genes as the basic unit of heredity, evolution as the engine that propels the creation and extinction of species. Living organisms are open systems that survive by transforming energy and decreasing their local entropy to maintain a stable and vital condition defined as homeostasis. Sub-disciplines of biology are defined by the research methods employed and the kind of system studied: theoretical biology uses mathematical methods to formulate quantitative models while experimental biology performs empirical experiments to test the validity of proposed theories and understand the mechanisms underlying life and how it appeared and evolved from non-living matter about 4 billion years ago through a gradual increase in the complexity of the system.
See branches of biology. The term biology is derived from the Greek word βίος, bios, "life" and the suffix -λογία, -logia, "study of." The Latin-language form of the term first appeared in 1736 when Swedish scientist Carl Linnaeus used biologi in his Bibliotheca botanica. It was used again in 1766 in a work entitled Philosophiae naturalis sive physicae: tomus III, continens geologian, phytologian generalis, by Michael Christoph Hanov, a disciple of Christian Wolff; the first German use, was in a 1771 translation of Linnaeus' work. In 1797, Theodor Georg August Roose used the term in the preface of a book, Grundzüge der Lehre van der Lebenskraft. Karl Friedrich Burdach used the term in 1800 in a more restricted sense of the study of human beings from a morphological and psychological perspective; the term came into its modern usage with the six-volume treatise Biologie, oder Philosophie der lebenden Natur by Gottfried Reinhold Treviranus, who announced: The objects of our research will be the different forms and manifestations of life, the conditions and laws under which these phenomena occur, the causes through which they have been effected.
The science that concerns itself with these objects we will indicate by the name biology or the doctrine of life. Although modern biology is a recent development, sciences related to and included within it have been studied since ancient times. Natural philosophy was studied as early as the ancient civilizations of Mesopotamia, the Indian subcontinent, China. However, the origins of modern biology and its approach to the study of nature are most traced back to ancient Greece. While the formal study of medicine dates back to Hippocrates, it was Aristotle who contributed most extensively to the development of biology. Important are his History of Animals and other works where he showed naturalist leanings, more empirical works that focused on biological causation and the diversity of life. Aristotle's successor at the Lyceum, wrote a series of books on botany that survived as the most important contribution of antiquity to the plant sciences into the Middle Ages. Scholars of the medieval Islamic world who wrote on biology included al-Jahiz, Al-Dīnawarī, who wrote on botany, Rhazes who wrote on anatomy and physiology.
Medicine was well studied by Islamic scholars working in Greek philosopher traditions, while natural history drew on Aristotelian thought in upholding a fixed hierarchy of life. Biology began to develop and grow with Anton van Leeuwenhoek's dramatic improvement of the microscope, it was that scholars discovered spermatozoa, bacteria and the diversity of microscopic life. Investigations by Jan Swammerdam led to new interest in entomology and helped to develop the basic techniques of microscopic dissection and staining. Advances in microscopy had a profound impact on biological thinking. In the early 19th century, a number of biologists pointed to the central importance of the cell. In 1838, Schleiden and Schwann began promoting the now universal ideas that the basic unit of organisms is the cell and that individual cells have all the characteristics of life, although they opposed the idea that all cells come from the division of other cells. Thanks to the work of Robert Remak and Rudolf Virchow, however, by the 1860s most biologists accepted all three tenets of what came to be known as cell theory.
Meanwhile and classification became the focus of natural historians. Carl Linnaeus published a basic taxonomy for the natural world in 1735, in the 1750s introduced scientific names for all his species. Georges-Louis Leclerc, Comte de Buffon, treated species as artificial categories and living forms as malleable—even suggesting the possibility of common descent. Although he was opposed to evolution, Buffon is a key figure in the history of evolutionary thought. Serious evolutionary thinking originated with the works of Jean-Baptiste Lamarck, the first to present a coherent theory of evolution, he posited that evolution was the result of environmental stress on properties of animals, meaning that the more and rigorously an organ was used, the more complex and efficient it would become, thus adapting the animal to its environment. Lamarck believed that these acquired traits could be passed on to the animal's offspring, who would
Nest
A nest is a structure built by certain animals to hold eggs and the animal itself. Although nests are most associated with birds, members of all classes of vertebrates and some invertebrates construct nests, they may be composed of organic material such as twigs and leaves, or may be a simple depression in the ground, or a hole in a rock, tree, or building. Human-made materials, such as string, cloth, or paper, may be used. Nests can be found in all types of habitat. Nest building is driven by a biological urge known as the nesting instinct in mammals; each species has a distinctive style of nest. Nest complexity is correlated with the level of parental care by adults. Nest building is considered a key adaptive advantage among birds, they exhibit the most variation in their nests ranging from simple holes in the ground to elaborate communal nests hosting hundreds of individuals. Nests of prairie dogs and several social insects can host millions of individuals. Nest building is driven by a biological urge in pregnant animals to protect one's offspring known as the nesting instinct.
Animals build nests to protect their offspring, or themselves from danger. The simplest nest structures are adapted to hide eggs from predators, shield them from the sun or other environmental factors, or keep them from being scattered in ocean currents. In some cases, nests help provide safety in numbers for egg-laying animals. Many nest builders provide parental care to their young, while others lay their eggs and leave. Brooding is common among birds. In general, nest complexity increases in relation to the level of parental care provided. Nest building reinforces social behavior, allowing for larger populations in small spaces to the point of increasing the carrying capacity of an environment. Insects that exhibit the most complex nest building exhibit the greatest social structure. Among mammals, the naked mole-rat displays a caste structure similar to the social insects while building extensive burrows that house hundreds of individuals. Versatility in use of construction material may be a disadvantage.
The available evidence suggests that natural selection more favors specialization over flexibility in nest construction. At the most basic level, there are only two types of nest building: assembly. Sculpting is the process of removing material to achieve a desired outcome. Most this entails burrowing into the ground or plant matter to create a nesting site. Assembly entails gathering and arranging materials to create a novel structure. Transportation has the greatest time and energy cost so animals are adapted to build with materials available in their immediate environment. Plant matter is the most common construction material for nests. Other common materials include fur or feathers from the animal itself, mud or dirt, fecal matter, specialized secretions from the animal's body. Nest building can have a substantial impact on the environment; the combined digging activity of termites and mole-rats in South Africa has created a "mima prairie" landscape marked by huge areas of flat land punctuated by mounds 30 metres wide and 2 metres high.
Similar structures exist in the United States, created by pocket gophers, Argentina, rodents of the genus Ctenomys. Nests constructed by megapode birds have been mistaken for anthropological features by professionals, due to their exceptional height and abundance. Nest architecture may be as useful for distinguishing species as the animals' physical appearance. Species identified through such means are called ethospecies; this is common in wasps and termites, but can apply to birds. In most animals, there is some variation in nest construction between individuals. Whether these differences are driven by genetics or learned behavior is unknown. With the exception of a few tunneling mammals, nest builders exhibit no specialized anatomy, instead making use of body parts used for other purposes; this is due to the sporadic nature of nest building, minimizing the selective pressures of anatomy used for nest building. In general, birds are the most skilled nest builders, although not all species of birds build nests, some laying their eggs directly onto rock ledges or bare soil without first modifying the area.
Complex nest building is considered to be one of the key adaptive advantages of birds. Nests help regulate temperature and reduce predation risks, thus increasing the chance that offspring live to adulthood. Bird nests vary from simple depressions in the ground known as scrapes to unstructured collections of branches to elaborately woven pendants or spheres; the megapodes, one of the few groups who do not directly brood their young, incubate their young in a mound of decomposing vegetation. One species, Macrocephalon maleo, uses volcanic sand warmed by geothermal heat to keep its eggs warm. Among the simple nest builders are falcons and many shorebirds; the weavers exhibit the most elaborate nests, complete with strands of grass tied into knots. Most bird nests lie somewhere in the middle, with the majority building cup-shaped nests using some combination of mud and leaves, feathers; some birds, such flamingos and swifts, use saliva to help hold their nest together. The edible-nest swiftlet uses saliva alone to construct their nests.
The rufous hornero nest is composed of mud and feces, placed on tree branches to allow the sun to ha
Dragonfly
A dragonfly is an insect belonging to the order Odonata, infraorder Anisoptera. Adult dragonflies are characterized by large, multifaceted eyes, two pairs of strong, transparent wings, sometimes with coloured patches, an elongated body. Dragonflies can be mistaken for the related group, which are similar in structure, though lighter in build. Dragonflies are agile fliers. Many dragonflies have brilliant iridescent or metallic colours produced by structural coloration, making them conspicuous in flight. An adult dragonfly's compound eyes have nearly 24,000 ommatidia each. Fossils of large dragonfly ancestors in the Protodonata are found from 325 million years ago in Upper Carboniferous rocks. There are about 3,000 extant species. Most are tropical, with fewer species in temperate regions. Dragonflies are predators, both in their aquatic larval stage, they are known as nymphs or naiads, as adults. Several years of their lives are spent as nymphs living in fresh water, they are fast, agile fliers, sometimes migrating across oceans, live near water.
They have a uniquely complex mode of reproduction involving indirect insemination, delayed fertilization, sperm competition. During mating, the male grasps the female at the back of the head, the female curls her abdomen under her body to pick up sperm from the male's secondary genitalia at the front of his abdomen, forming the "heart" or "wheel" posture. Loss of wetland habitat threatens dragonfly populations around the world. Dragonflies are represented in human culture on artifacts such as pottery, rock paintings, Art Nouveau jewellery, they are used in traditional medicine in Japan and China, caught for food in Indonesia. They are symbols of courage and happiness in Japan, but seen as sinister in European folklore, their bright colours and agile flight are admired in the poetry of Lord Tennyson and the prose of H. E. Bates. Dragonflies and their relatives are an ancient group; the oldest fossils are of the Protodonata from the 325 Mya Upper Carboniferous of Europe, a group that included the largest insect that lived, Meganeuropsis permiana from the early Permian, with a wingspan around 750 mm.
The Protanisoptera, another ancestral group which lacks certain wing vein characters found in modern Odonata, lived from the Early to Late Permian age until the end Permian event, are known from fossil wings from current day United States and Australia, suggesting they might have been cosmopolitan in distribution. The forerunners of modern Odonata are included in a clade called the Panodonata, which include the basal Zygoptera and the Anisoptera. Today there are some 3000 species extant around the world; the relationships of anisopteran families are not resolved as of 2013, but all the families are monophyletic except the Corduliidae. On the cladogram, dashed lines indicate unresolved relationships; the distribution of diversity within the biogeographical regions are summarised below. Dragonflies live on every continent except Antarctica. In contrast to the damselflies, which tend to have restricted distributions, some genera and species are spread across continents. For example, the blue-eyed darner Rhionaeschna multicolor lives all across North America, in Central America.
The globe skimmer Pantala flavescens is the most widespread dragonfly species in the world. Most Anisoptera species are tropical, with far fewer species in temperate regions; some dragonflies, including libellulids and aeshnids, live in desert pools, for example in the Mojave Desert, where they are active in shade temperatures between 18 and 45 °C. Dragonflies live from sea level up to the mountains, their altitudinal limit is about 3700 m, represented by a species of Aeshna in the Pamirs. Dragonflies become scarce at higher latitudes, they are not native to Iceland, but individuals are swept in by strong winds, including a Hemianax ephippiger native to North Africa, an unidentified darter species. In Kamchatka, only a few species of dragonfly including the treeline emerald Somatochlora arctica and some aeshnids such as Aeshna subarctica are found because of the low temperature of the lakes there; the treeline emerald lives in northern Alaska, within the Arctic Circle, making it the most northerly of all dragonflies.
Dragonflies are heavy-bodied, strong-flying insects that hold their win
Arthropod
An arthropod is an invertebrate animal having an exoskeleton, a segmented body, paired jointed appendages. Arthropods form the phylum Euarthropoda, which includes insects, arachnids and crustaceans; the term Arthropoda as proposed refers to a proposed grouping of Euarthropods and the phylum Onychophora. Arthropods are characterized by their jointed limbs and cuticle made of chitin mineralised with calcium carbonate; the arthropod body plan consists of each with a pair of appendages. The rigid cuticle inhibits growth, so arthropods replace it periodically by moulting. Arthopods are bilaterally symmetrical and their body possesses an external skeleton; some species have wings. Their versatility has enabled them to become the most species-rich members of all ecological guilds in most environments, they have over a million described species, making up more than 80 per cent of all described living animal species, some of which, unlike most other animals, are successful in dry environments. Arthropods range in size from the microscopic crustacean Stygotantulus up to the Japanese spider crab.
Arthropods' primary internal cavity is a haemocoel, which accommodates their internal organs, through which their haemolymph – analogue of blood – circulates. Like their exteriors, the internal organs of arthropods are built of repeated segments, their nervous system is "ladder-like", with paired ventral nerve cords running through all segments and forming paired ganglia in each segment. Their heads are formed by fusion of varying numbers of segments, their brains are formed by fusion of the ganglia of these segments and encircle the esophagus; the respiratory and excretory systems of arthropods vary, depending as much on their environment as on the subphylum to which they belong. Their vision relies on various combinations of compound eyes and pigment-pit ocelli: in most species the ocelli can only detect the direction from which light is coming, the compound eyes are the main source of information, but the main eyes of spiders are ocelli that can form images and, in a few cases, can swivel to track prey.
Arthropods have a wide range of chemical and mechanical sensors based on modifications of the many setae that project through their cuticles. Arthropods' methods of reproduction and development are diverse; the evolutionary ancestry of arthropods dates back to the Cambrian period. The group is regarded as monophyletic, many analyses support the placement of arthropods with cycloneuralians in a superphylum Ecdysozoa. Overall, the basal relationships of Metazoa are not yet well resolved; the relationships between various arthropod groups are still debated. Aquatic species use either external fertilization. All arthropods lay eggs, but scorpions give birth to live young after the eggs have hatched inside the mother. Arthropod hatchlings vary from miniature adults to grubs and caterpillars that lack jointed limbs and undergo a total metamorphosis to produce the adult form; the level of maternal care for hatchlings varies from nonexistent to the prolonged care provided by scorpions. Arthropods contribute to the human food supply both directly as food, more indirectly as pollinators of crops.
Some species are known to spread severe disease to humans and crops. The word arthropod comes from the Greek ἄρθρον árthron, "joint", πούς pous, i.e. "foot" or "leg", which together mean "jointed leg". Arthropods are invertebrates with jointed limbs; the exoskeleton or cuticles consists of a polymer of glucosamine. The cuticle of many crustaceans, beetle mites, millipedes is biomineralized with calcium carbonate. Calcification of the endosternite, an internal structure used for muscle attachments occur in some opiliones. Estimates of the number of arthropod species vary between 1,170,000 and 5 to 10 million and account for over 80 per cent of all known living animal species; the number of species remains difficult to determine. This is due to the census modeling assumptions projected onto other regions in order to scale up from counts at specific locations applied to the whole world. A study in 1992 estimated that there were 500,000 species of animals and plants in Costa Rica alone, of which 365,000 were arthropods.
They are important members of marine, freshwater and air ecosystems, are one of only two major animal groups that have adapted to life in dry environments. One arthropod sub-group, insects, is the most species-rich member of all ecological guilds in land and freshwater environments; the lightest insects weigh less than 25 micrograms. Some living crustaceans are much larger; the embryos of all arthropods are segmented, built from a series of repeated modules. The last common ancestor of living arthropods consisted of a series of undifferentiated segments, each with a pair of appendages that functioned as limbs. However, all known living and fossil arthropods have grouped segments into tagmata in which segments and their limbs are specialized in various ways; the three-
Banana slug
Banana slugs are North American terrestrial slugs comprising the genus Ariolimax. These slugs are yellow in color and are sometimes spotted with brown blotches, resembling a ripe banana, the source of their common name, although they can come in other colours. Species within the genus Ariolimax include: Banana slugs are bright yellow although they may be greenish, tan, or white; the species Ariolimax columbianus sometimes has black spots that are so extensive that the animal looks entirely black. Individual slugs will change colors with alterations in food consumption, light exposure, moisture levels. Color may indicate whether a slug is healthy or injured or what age it is; the Pacific banana slug is the second-largest species of terrestrial slug in the world, growing up to 25 centimetres long, weights of 115 grams. Banana slugs have an average lifespan of 1–7 years. Banana slugs have a ribbon-like anatomical structure covered in rows of microscopic teeth. Individuals can move at 6 1⁄2 inches per minute.
Slugs use two pairs of tentacles to sense their environment. The larger, upper pair, termed "eyestalks," are used to detect movement; the second, lower pair are used to detect chemicals. The tentacles can extend themselves to avoid damage. If a predator bites off a tentacle, the slug can grow a new one. Banana slugs have a single lung; the pneumostome lung cavity is vascularized to allow gas exchange. Dehydration is a major problem for the mollusk. To do so, they secrete a protective layer of mucus and insulate themselves with a layer of soil and leaves, they remain inactive in this state. Due to their susceptibility to desiccation, they are more active at night, but appear during cool, moist days; the slime contains pheromones to attract other slugs for mating. Slugs are simultaneous hermaphrodites, reproduce by exchanging sperm with their mate, they produce up to 75 translucent eggs, which are laid on leaves. Slugs lay eggs throughout the year; the adults provide no further care for their eggs beyond finding a suitable hiding spot, the eggs are abandoned as soon as the clutch is laid.
Ariolimax columbianus is native to the forest floors along North America's Pacific coastal coniferous rainforest belt which stretches from Southeastern Alaska to Santa Cruz, California. Several discontinuous populations occur in forested slopes of the coastal and transverse mountain ranges south of Santa Cruz as far south as Ventura County, with a tiny, isolated population located in Palomar Mountain State Park within the Palomar Mountain Range in San Diego County, California; the Palomar Mountains have lush Sierra Nevada-like coniferous forests and black oak woodlands unlike the surrounding semiarid lands of inland San Diego County and mark the southernmost population of banana slugs. The slugs were rediscovered several years ago along Doane Creek, part of the Lower Doane Valley/Lower French Trail; this population is believed to be a relict from the Pleistocene epoch when the climate was cooler and wetter. Small, isolated populations occur east of the Pacific Coast such as in the inland coniferous rainforests of British Columbia's Columbia Mountains, just west of the Canadian Rockies, have been seen at lower elevations near creeks and damp areas of Mount Revelstoke National Park.
Small populations of banana slugs have been seen along creek and damp areas of the western slopes of the Sierra Nevada mountains to the north of Yosemite National Park in California. Slug densities in these outlying areas in the Columbia Mountains, Sierra Nevada Mountains, areas south of Santa Cruz are low compared to densities in the coastal coniferous rainforest belt and are rather restricted to damp areas near creeks and gullies; this population may be a relic from the Pleistocene epoch. Banana slugs decomposers, they process leaves, animal droppings and dead plant material, recycle them into soil humus. They seem to have a fondness for mushrooms, spread seeds and spores when they eat, excrete a nitrogen rich fertilizer. By consuming detritus slugs contribute to decomposition and the nutrient cycles and are an important aspect of the ecosystem. Raccoons, garter snakes, ducks and salamanders sometimes eat banana slugs. Juvenile banana slugs are sometimes eaten by shrews; the mucus secreted by banana slugs contains chemicals.
This mucus can absorb up to 100 times its volume in water. Technically, this slime is not a liquid nor solid, but rather a liquid crystal substance and has many properties that interest materials engineers. Banana slugs have been used as food by Yurok Indians of the North Coast and by German immigrants in the 19th and early 20th centuries. A yearly festival and contest is held at Russian River including slug races and a contest for recipes — though when fed corn meal to purge them or soaked in vinegar to remove slime, the slugs' flavor is not always well regarded, the most successful entries are those in which the flavor is unnoticeable; the banana slug is the mascot of the University of Santa Cruz. It is common in local for
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