An ectotherm, is an organism in which internal physiological sources of heat are of small or quite negligible importance in controlling body temperature. Such organisms rely on environmental heat sources, which permit them to operate at economical metabolic rates; some of these animals live in environments where temperatures are constant, as is typical of regions of the abyssal ocean and hence can be regarded as homeothermic ectotherms. In contrast, in places where temperature varies so as to limit the physiological activities of other kinds of ectotherms, many species habitually seek out external sources of heat or shelter from heat. For home captivity as pet, reptile owners can use a UVB/UVA light system to assist the animals' basking behaviour. In contrast to ectotherms, endotherms rely even predominantly, on heat from internal metabolic processes, mesotherms use an intermediate strategy. In ectotherms, fluctuating ambient temperatures may affect the body temperature; such variation in body temperature is called poikilothermy, though the concept is not satisfactory and the use of the term is declining.
In small aquatic creatures such as Rotifera, the poikilothermy is absolute, but other creatures have wider physiological options at their disposal, they can move to preferred temperatures, avoid ambient temperature changes, or moderate their effects. Ectotherms can display the features of homeothermy within aquatic organisms, their range of ambient environmental temperatures is constant, there are few in number that attempt to maintain a higher internal temperature due to the high associated costs. Various patterns of behavior enable certain ectotherms to regulate body temperature to a useful extent. To warm up, reptiles and many insects find sunny places and adopt positions that maximise their exposure. In cold weather, honey bees huddle together to retain heat. Butterflies and moths may orient their wings to maximize exposure to solar radiation in order to build up heat before take-off. Gregarious caterpillars, such as the Forest Tent caterpillar and fall webworm, benefit from basking in large groups for thermoregulation.
Many flying insects, such as honey bees and bumble bees raise their internal temperatures endothermally prior to flight, by vibrating their flight muscles without violent movement of the wings. Such endothermal activity is an example of the difficulty of consistent application of terms such as poikilothermy and homiothermy. In addition to behavioral adaptations, physiological adaptations help ectotherms regulate temperature. Diving reptiles conserve heat by heat exchange mechanisms, whereby cold blood from the skin picks up heat from blood moving outward from the body core, re-using and thereby conserving some of the heat that otherwise would have been wasted; the skin of bullfrogs secretes more mucus when it is hot. During periods of cold, some ectotherms enter a state of torpor, in which their metabolism slows or, in some cases, such as the wood frog stops; the torpor might last overnight or last for a season, or for years, depending on the species and circumstances. Ectotherms rely on external heat sources such as sunlight to achieve their optimal body temperature for various bodily activities.
Accordingly, they depend on ambient conditions to reach operational body temperatures. In contrast, endothermic animals, as a rule, maintain nearly constant high operational body temperatures by reliance on internal heat produced by metabolically active organs or by specialized heat producing organs like brown adipose tissue; as a rule, ectotherms have lower metabolic rates than endotherms at a given body mass. As a consequence, endotherms rely on higher food consumption, on food of higher energy content; such requirements may limit the carrying capacity of a given environment for endotherms as compared to its carrying capacity for ectotherms. Because ectotherms depend on environmental conditions for body temperature regulation, as a rule, they are more sluggish at night and in early mornings; when they emerge from shelter, many diurnal ectotherms need to heat up in the early sunlight before they can begin their daily activities. In cool weather the foraging activity of such species is therefore restricted to the day time in most vertebrate ectotherms, in cold climates most cannot survive at all.
In lizards, for instance, most nocturnal species are geckos specialising in "sit and wait" foraging strategies. Such strategies do not require as much energy as active foraging and do not, as a rule, require hunting activity of the same intensity. From another point of view, sit-and-wait predation may require long periods of unproductive waiting. Endotherms cannot, in general, afford such long periods without food, but suitably adapted ectotherms can wait without expending much energy. Endothermic vertebrate species are therefore less dependent on the environmental conditions and have developed a higher variability in their daily patterns of activity. Possible confusion can arise from the difference in the terminology of biology. Whereas the thermodynamic terms "exothermic" and "endothermic" refer to processes that give out heat energy and processes that absorb heat energy
The Pythonidae known as pythons, from the Greek word python, are a family of nonvenomous snakes found in Africa and Australia. Among its members are some of the largest snakes in the world. Eight genera and 31 species are recognized. Pythons are found in sub-Saharan Africa, India, Sri Lanka, southern China, Ryukyu Islands in southern Japan, Southeast Asia, from the Philippines southeast through Indonesia to New Guinea and Australia. In the United States, an introduced population of Burmese pythons, Python molurus bivittatus, has existed as an invasive species in the Everglades National Park since the late 1990s. Many species have been hunted aggressively, which has reduced the population of some, such as the Indian python, Python molurus. Most members of this family are ambush predators, in that they remain motionless in a camouflaged position, strike at passing prey. Attacks on humans, although known to occur, are rare. Pythons use their sharp, backward-curving teeth, four rows in the upper jaw, two in the lower, to grasp prey, killed by constriction.
Death occurs by cardiac arrest. Larger specimens eat animals about the size of a house cat, but larger food items are known. In 2017, there was a recorded case of a human devoured by a python in Indonesia. All prey is swallowed whole, may take several days or weeks to digest. Contrary to popular belief the larger species, such as the reticulated python, P. reticulatus, do not crush their prey to death. The speed with which the coils are applied is impressive and the force they exert may be significant, but death is caused by cardiac arrest. Pythons are oviparous; this sets them apart from the family Boidae. After they lay their eggs, females incubate them until they hatch; this is achieved by causing the muscles to "shiver", which raises the temperature of the body to a certain degree, thus that of the eggs. Keeping the eggs at a constant temperature is essential for healthy embryo development. During the incubation period, females do not eat and leave only to bask to raise their body temperature.
Most species in this family are available in the exotic pet trade. However, caution must be exercised with the larger species. *) Not including the nominate subspecies. T) Type genus. Obsolete classification schemes—such as that of Boulenger —place pythons in Pythoninae, a subfamily of the boa family, Boidae. However, despite a superficial resemblance to boas, pythons are more related to sunbeam snakes and burrowing pythons. Pythonidae at the Reptarium.cz Reptile Database. Accessed 3 November 2008. Pythons at Answers.com. Accessed 3 November 2008
Boiga is a large genus of opisthoglyphous, mildly venomous snakes, known as cat-eyed snakes or cat snakes, in the family Colubridae. Species of the genus Boiga are endemic to southeast Asia and Australia, but due to their hardy nature and adaptability, have spread to many other suitable habitats around the world. There are 34 recognized species in the genus. According to the study done by Jiri Smid regarding Old World cat snakes, the ancestor of the cat snake originated in Africa, from where it diversified and expanded to other countries. Despite this diversity however, the different species have similar needs in terms of temperature and precipitation. Boiga andamanensis – Andaman cat snake Boiga angulata – Leyte cat snake Boiga barnesii – Barnes' cat snake Boiga beddomei – Beddome's cat snake Boiga bengkuluensis Orlov, Ryabov & Shumakov, 2003 Boiga blandingii – Blanding's tree snake Boiga bourreti Tillack, Ziegler & Le Khac Quyet, 2004 Boiga ceylonensis – Sri Lanka cat snake Boiga cyanea – green cat snake Boiga cynodon – dog-toothed cat snake Boiga dendrophila – gold-ringed cat snake, mangrove snake Boiga dendrophila annectens Boiga dendrophila dendrophila Boiga dendrophila divergens Taylor, 1922 Boiga dendrophila gemmicincta Boiga dendrophila latifasciata Boiga dendrophila levitoni Gaulke, Demegillo & G. Vogel, 2005 Boiga dendrophila melanota Boiga dendrophila multicincta Boiga dendrophila occidentalis Brongersma, 1934 Boiga dightoni – Pirmad cat snake Boiga drapiezii – white-spotted cat snake Boiga flaviviridis G. Vogel & Ganesh, 2013 Boiga forsteni – Forsten's cat snake Boiga gocool – arrowback tree snake Boiga guangxiensis Wen, 1998 Boiga hoeseli Ramadhan, Iskandar & Subasri, 2010 Boiga irregularis – brown tree snake Boiga jaspidea – jasper cat snake Boiga kraepelini – Kelung cat snake Boiga multifasciata – many-banded cat snake Boiga multomaculata – many-spotted cat snake Boiga nigriceps – black-headed cat snake Boiga nuchalis – Ashahar's cat snake Boiga ochracea – tawny cat snake Boiga philippina – Philippine cat snake Boiga quincunciata Boiga saengsomi Nutphand, 1985 – banded cat snake Boiga schultzei Taylor, 1923 – Schultze's blunt-headed tree snake Boiga siamensis – gray cat snake Boiga tanahjampeana Orlov & Ryabov, 2002 Boiga trigonata – Indian gamma snake Boiga trigonata trigonata Boiga trigonata melanocephala Boiga wallachi Das, 1998 – Nicobar cat snake Boiga westermanni Reinhardt, 1863 – Indian egg-eating snakeNota bene: A binomial authority in parentheses indicates that the species was original described in a genus other than Boiga.
Cat snakes are long-bodied snakes with large eyes. They vary in pattern and color. Many species have banding. Colors are black, brown, or green with white or yellow accents, they are arboreal, nocturnal snakes. They prey on various species of lizards, small snakes, birds, they feed on other mammals in the wild, their venom toxicity varies from species to species, but is not considered to be life-threatening to humans. Since their venom doesn't harm humans, they are popular exotic pets. Boiga species are oviparous. Boiga dendrophila is by far the most common species in captivity, but Boiga cynea and Boiga nigriceps are found. Nowadays, B. cynodon, B. philippina and a “Katherine morph” B. irregularis are circulating in the South-East Asian exotic pet trade. Others are not available, they are hardy and adaptable and tend to do well in captivity after the initial period of stress from the importation process is passed. They are not bred in captivity, so most specimens available are wild caught, thus are prone to heavy internal parasite load.
Adjusting them to a rodent only diet can be difficult for the inexperienced reptile keeper. Boiga irregularis in particular has been federally banned in the United States because of its effect by accidentally being introduced to the island of Guam; some time during the 1950s, these snakes reached the island having hidden in imported plant pots. The island of Guam lacks native snakes or predators that can deal with snakes the size and aggressiveness of Boiga irregularis; as a result, they have bred unchecked as an invasive species, began consuming the island's bird life in extreme numbers. Dozens of bird species have been eradicated from the island, many species that were found nowhere else on earth, the snake has reached astonishing population densities, reported to be as high as 15,000 snakes per square mile. In addition to devouring the native fauna, this species will crawl into power transformers, for all involved, this results in both an electrocuted snake and substantial blackouts. Fitzinger LI.
Neue Classification der Reptilien nach ihren natürlichen Verwandtschaften. Nebst einer Verwandtschafts-tafel und einem Verzeichnisse der Reptilien-Sammlung des k.k. zoologischen Museums zu Wien. Vienna: J. G. Heubner. Five unnumbered + 67 pp. + one plate... Genus Boi
Simoselaps, or Australian coral snakes, is a genus composed of 13 species of venomous elapid snakes. Species of the genus Simoselaps are found throughout Australia. Australian coral snakes are small snakes, they have smooth and polished scales, shovel-shaped snouts, are brightly marked with bands or annuli. Species of Simoselaps are found in arid regions, they are burrowing snakes which move beneath the surface through loose soil. At night they come to the surface to feed on reptile eggs. All species of Australian coral snakes lay clutches of three to five eggs. Several of the above species are sometimes placed in the genus Brachyurophis. Cogger HG. Reptiles and Amphibians of Australia, Sixth Edition. Sanibel Island, Florida: Ralph Curtis Publishing. 808 pp. Horner P. "Simoselaps morrisi sp. nov. A new species of snake of the Northern Territory"; the Beagle 14: 63-70. Jan. "Plan d'une Iconographie descriptive des Ophidiens et Description sommaire de nouvelles espèces de Serpents ". Revue et Magasin de Zoologie Pure et Apliquée, Series 2, 11: 122-130...
Storr GM. "Taxonomic notes on the reptiles of the Shark Bay region, Western Australia". Records of the Western Australian Museum 6: 303-318. Genus Brachyurophis at The Reptile Database Genus Simoselaps at The Reptile Database "Simoselaps". Integrated Taxonomic Information System
The Crotalinae known as pit vipers, crotaline snakes, or pit adders, are a subfamily of venomous vipers found in Eurasia and the Americas. They are distinguished by the presence of a heat-sensing pit organ located between the eye and the nostril on both sides of the head. 18 genera and 151 species are recognized: seven genera and 54 species in the Old World, against a greater diversity of 11 genera and 97 species in the New World. These are the only viperids found in the Americas; the groups of snakes represented here include rattlesnakes and Asian pit vipers. The type genus for this subfamily is Crotalus, of which the type species is the timber rattlesnake, C. horridus. These snakes range in size from the diminutive hump-nosed viper, Hypnale hypnale, that grows to an average total length of only 30–45 cm, to the bushmaster, Lachesis muta, a species known to reach a maximum total length of 3.65 m in length. What makes this subfamily unique is that all member species share a common characteristic: a deep pit, or fossa, in the loreal area between the eye and the nostril on either side of the head.
These loreal pits are the external openings to a pair of sensitive infrared-detecting organs, which in effect give the snakes a sixth sense to help them find and even judge the size of the small, warm-blooded prey on which they feed. Osine triphosphate, monoamine oxidase, generalized esterases and acetylcholine esterase have been found in it; when prey comes into range, infrared radiation falling onto the membrane allows the snake to determine its direction. Experiments have shown, when deprived of their senses of sight and smell, these snakes can strike at moving objects less than 0.2 °C warmer than the background. The paired pit organs provide the snake with thermal rangefinder capabilities; these organs are of great value to a predator that hunts at night, as well as for avoiding the snake’s own predators. Among vipers, these snakes are unique in that they have a specialized muscle, called the muscularis pterigoidius glandulae, between the venom gland and the head of the ectopterygoid. Contraction of this muscle, together with that of the m. compressor glandulae, forces venom out of the gland.
The subfamily Crotalinae is found in the Old World from eastern Europe eastward through Asia to Japan, Indonesia, peninsular India and Sri Lanka. In the Americas, they range from southern Canada southward to Central America to southern South America. Crotalines are a versatile subfamily, with members found in habitats ranging from parched desert to rainforests, they may be either arboreal or terrestrial, one species is semiaquatic: the cottonmouth, Agkistrodon piscivorus. The altitude record is held jointly by Crotalus triseriatus in Mexico and Gloydius strauchi in China, both of which have been found above the treeline at over 4,000 m elevation. Although a few species of crotalines are active by day, such as Trimeresurus trigonocephalus, a bright green pit viper endemic to Sri Lanka, most are nocturnal, preferring to avoid high daytime temperatures and to hunt when their favored prey are active; the snakes' heat-sensitive pits are thought to aid in locating cooler areas in which to rest. As ambush predators, crotalines wait patiently somewhere for unsuspecting prey to wander by.
At least one species, the arboreal Gloydius shedaoensis of China, is known to select a specific ambush site and return to it every year in time for the spring migration of birds. Studies have indicated. Many temperate species of pit vipers congregate in sheltered areas or "dens" to overwinter, the snakes benefiting from the combined heat. In cool temperatures and while pregnant, pit vipers bask on sunny ledges; some species do not mass together in this way, for example the copperhead, Agkistrodon contortrix, or the Mojave rattlesnake, Crotalus scutulatus. Like most snakes, crotalines strike only if cornered or threatened. Smaller snakes are less to stand their ground than larger specimens. Pollution and the destruction of rainforests have caused many pit viper populations to decline. Humans threaten pit vipers, as many are hunted for their skins or killed by cars when they wander onto roads. With few exceptions, crotalines are ovoviviparous. Among the oviparous pit vipers are Lachesis and some Trimeresurus species.
All egg-laying crotalines are believed to guard their eggs. Brood sizes range from two for small species, to as many as 86 for the fer-de-lance, Bothrops atrox, a species among the most prolific of all live-bearing snakes. Many young crotalines have brightly coloured tails that contrast with the rest of their bodies. Used in a behavior known as caudal luring, the young snakes make worm-like movements with their tails to lure unsuspecting prey within striking distance. In the past, the pit vipers were classed as a separate family: the Crotalidae. Today, the monophyly of the viperines and the crotalines as a whole is undisputed, why they are treated here as a subfamily of the Viperidae. *) Not including the nominate subspecies. T) Type genus. List of crotaline species and subspecies Crotalinae by common name Crotalinae by taxonomic synonyms Pit organs at Life is Short, but Snakes are Long
Anacondas or water boas are a group of large snakes of the genus Eunectes. They are found in tropical South America. Four species are recognized. Although the name applies to a group of snakes, it is used to refer only to one species, in particular, the common or green anaconda, the largest snake in the world by weight, the second longest; the South American names anacauchoa and anacaona were suggested in an account by Peter Martyr d'Anghiera but the idea of a South American origin was questioned by Henry Walter Bates who, in his travels in South America, failed to find any similar name in use. The word anaconda is derived from the name of a snake from Ceylon that John Ray described in Latin in his Synopsis Methodica Animalium as serpens indicus bubalinus anacandaia zeylonibus, ides bubalorum aliorumque jumentorum membra conterens. Ray used a catalogue of snakes from the Leyden museum supplied by Dr. Tancred Robinson, but the description of its habit was based on Andreas Cleyer who in 1684 described a gigantic snake that crushed large animals by coiling around their bodies and crushing their bones.
Henry Yule in his Hobson-Jobson notes that the word became more popular due to a piece of fiction published in 1768 in the Scots Magazine by a certain R. Edwin. Edwin described a'tiger' being crushed to death by an anaconda, when there never were any tigers in Sri Lanka. Yule and Frank Wall noted that the snake was in fact a python and suggested a Tamil origin anai-kondra meaning elephant killer. A Sinhalese origin was suggested by Donald Ferguson who pointed out that the word Henakandaya was used in Sri Lanka for the small whip snake and somehow got misapplied to the python before myths were created; the name used for the anaconda in Brazil is sucuri, sucuriju or sucuriuba. The term "anaconda" has been used to refer to: Any member of the genus Eunectes, a group of large, aquatic snakes found in South America: Eunectes murinus, the green anaconda – the largest species, found east of the Andes in Colombia, the Guianas, Peru, Bolivia and Trinidad and Tobago Eunectes notaeus, the yellow anaconda – a small species, found in eastern Bolivia, southern Brazil and northeastern Argentina Eunectes deschauenseei, the darkly-spotted anaconda – a rare species, found in northeastern Brazil and coastal French Guiana Eunectes beniensis, the Bolivian anaconda – the most defined species, found in the Departments of Beni and Pando in Bolivia The giant anaconda, a mythical snake of enormous proportions said to be found in South America The term was applied imprecisely, indicating any large snake that constricts its prey, though this usage is now archaic.
South American jaguar, a competitor or predator
The brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. The brain is located in the head close to the sensory organs for senses such as vision; the brain is the most complex organ in a vertebrate's body. In a human, the cerebral cortex contains 14–16 billion neurons, the estimated number of neurons in the cerebellum is 55–70 billion; each neuron is connected by synapses to several thousand other neurons. These neurons communicate with one another by means of long protoplasmic fibers called axons, which carry trains of signal pulses called action potentials to distant parts of the brain or body targeting specific recipient cells. Physiologically, the function of the brain is to exert centralized control over the other organs of the body; the brain acts on the rest of the body both by generating patterns of muscle activity and by driving the secretion of chemicals called hormones. This centralized control allows coordinated responses to changes in the environment.
Some basic types of responsiveness such as reflexes can be mediated by the spinal cord or peripheral ganglia, but sophisticated purposeful control of behavior based on complex sensory input requires the information integrating capabilities of a centralized brain. The operations of individual brain cells are now understood in considerable detail but the way they cooperate in ensembles of millions is yet to be solved. Recent models in modern neuroscience treat the brain as a biological computer different in mechanism from an electronic computer, but similar in the sense that it acquires information from the surrounding world, stores it, processes it in a variety of ways; this article compares the properties of brains across the entire range of animal species, with the greatest attention to vertebrates. It deals with the human brain insofar; the ways in which the human brain differs from other brains are covered in the human brain article. Several topics that might be covered here are instead covered there because much more can be said about them in a human context.
The most important is brain disease and the effects of brain damage, that are covered in the human brain article. The shape and size of the brain varies between species, identifying common features is difficult. There are a number of principles of brain architecture that apply across a wide range of species; some aspects of brain structure are common to the entire range of animal species. The simplest way to gain information about brain anatomy is by visual inspection, but many more sophisticated techniques have been developed. Brain tissue in its natural state is too soft to work with, but it can be hardened by immersion in alcohol or other fixatives, sliced apart for examination of the interior. Visually, the interior of the brain consists of areas of so-called grey matter, with a dark color, separated by areas of white matter, with a lighter color. Further information can be gained by staining slices of brain tissue with a variety of chemicals that bring out areas where specific types of molecules are present in high concentrations.
It is possible to examine the microstructure of brain tissue using a microscope, to trace the pattern of connections from one brain area to another. The brains of all species are composed of two broad classes of cells: neurons and glial cells. Glial cells come in several types, perform a number of critical functions, including structural support, metabolic support and guidance of development. Neurons, are considered the most important cells in the brain; the property that makes neurons unique is their ability to send signals to specific target cells over long distances. They send these signals by means of an axon, a thin protoplasmic fiber that extends from the cell body and projects with numerous branches, to other areas, sometimes nearby, sometimes in distant parts of the brain or body; the length of an axon can be extraordinary: for example, if a pyramidal cell of the cerebral cortex were magnified so that its cell body became the size of a human body, its axon magnified, would become a cable a few centimeters in diameter, extending more than a kilometer.
These axons transmit signals in the form of electrochemical pulses called action potentials, which last less than a thousandth of a second and travel along the axon at speeds of 1–100 meters per second. Some neurons emit action potentials at rates of 10–100 per second in irregular patterns. Axons transmit signals to other neurons by means of specialized junctions called synapses. A single axon may make as many as several thousand synaptic connections with other cells; when an action potential, traveling along an axon, arrives at a synapse, it causes a chemical called a neurotransmitter to be released. The neurotransmitter binds to receptor molecules in the membrane of the target cell. Synapses are the key functional elements of the brain; the essential function of the brain is cell-to-cell communication, synapses are the points at which communication occurs. The human brain has been estimated to contain 100 trillion synapses; the functions of these synapses are diverse: some are excitatory.