From Wikipedia, the free encyclopedia This article is about writing prose. For writing style guides, see style guide.
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This article's tone or style may not reflect the formal tone used on Wikipedia. Specific concerns may be found on the talk page. See Wikipedia's guide to writing better articles for suggestions. (September 2009) Writing style is the manner in which an author chooses to write to his or her audience. A style reveals both the writer's personality and voice, but it also shows how she or he perceives the audience, and chooses conceptual writing style which reveal those choices by which the writer may change the conceptual world of the overall character of the work. This might be done by a simple change of words; a syntactical structure, parsing prose, adding diction, and organizing figures of thought into usable frameworks. Certainly, there are similar and analogous questions of style and audience that exist in the choices of expressive possibilities in speech. Contents [hide] 1 Constraints on style 1.1 Situation and purpose 2 Stylistic choices 2.1 Sentence forms 2.1.1 The loose sentence 2.1.2 The periodic sentence 2.1.3 The balanced sentence 2.1.4 Diction 2.2 Connotation 2.3 Punctuation 2.3.1 Clichés 3 Bibliography 4 See also [edit]Constraints on style
[edit]Situation and purpose The writer needs to tailor style to the situation. For example, the same person writing a letter to the same reader would use a different style depending on whether it is a letter of complaint, a letter of condolence, or a business letter. The author needs to decide whether the goal of the writing is to inform, persuade, or entertain. [edit]Stylistic choices
[edit]Sentence forms A writer controls not only the density of prose but its distribution. Within the rules of grammar, the writer can arrange words in many ways. A sentence may state the main proposition first and then modify it; or it may contain language to prepare the reader before stating the main proposition. Varying the style may avoid monotony. However, in technical writing, using different styles to make two similar utterances makes the reader ask whether the use of different styles was intended to carry additional meaning. Stylistic choices may be influenced by the culture. In the modern age, for instance, the loose sentence has been favored in all modes of discourse. In classical times, the periodic sentence held equal or greater favor, and during the Age of Enlightenment, the balanced sentence was a favorite of writers. [edit]The loose sentence The most common sentence in modern usage, the loose sentence begins with the main point (an independent clause), followed by one or more subordinate clauses. For example: Uncle Tom's Cabin is a very influential novel, having its self-righteous, virtuous sentimentality, much in common with Cat in the Hat. The cat sat on the mat, purring softly, having licked his paws. According to Francis Christensen: The loose sentence ... characterized the anti-Ciceronian movement in the seventeenth century. This movement, according to Morris W. Croll [“The Baroque Style in Prose,” (1929)] began with Montaigne and Bacon and continued with such men as Donne, Browne, Taylor, Pascal. To Montaigne, its art was the art of being natural; to Pascal, its eloquence was the eloquence that mocks formal eloquence; to Bacon, it presented knowledge so that it could be examined, not so that it must be accepted. (in Winterowd, 'Contemporary Rhetoric: A Conceptual Background with Readings,' p.348) [edit]The periodic sentence In general, a periodic sentence places the main point in the middle or at the end of the sentence. In the former case, the main point is modified by subordinate clauses before and after its position in the sentence. In the latter case, the main point is modified by preceding subordinate clauses. Under a government which imprisons any unjustly, the true place for a just man is also a prison. (Henry David Thoreau) The purpose of such form is well-stated by Adams Sherman Hill in The Foundation of Rhetoric (1897): To secure force in a sentence, it is necessary not only to choose the strongest words and to be as concise as is consistent with clearness, but also to arrange words, phrases, and clauses in the order which gives a commanding position to what is most important, and thus fixes the attention on the central idea. [edit]The balanced sentence A balanced sentence is characterized by parallel structure: two or more parts of the sentence have the same form, emphasizing similarities or differences. [edit]Diction Depending on the mode in which the writer is writing, diction can also pertain to the writer's style. Argumentative and expository prose on a particular subject matter frequently makes use of a set of jargon in which the subject matter is commonly discussed. By contrast, narrative and descriptive prose is open to the vast variety of words. Insofar as a style of diction can be discerned, however, it is best to examine the diction against a number of spectrums: Abstract-concrete: how much of the diction is physical? General-specific: to what degree is the diction precise, to what degree is it vague? Denotation-connotation Literal-metaphorical Other attributes of diction include: Density Length [edit]Connotation The connotation of a word refers to the special meaning , apart from its dictionary definition, that it may convey. Connotation especially depends on the audience. The word "dog" denotes any animal from the genus canis, but it may connote friendship to one reader and terror to another. This partly depends on the reader's personal dealings with dogs, but the author can provide context to guide the reader's interpretation. Deliberate use of connotation may involve selection of a word to convey more than its dictionary meaning, or substitution of another word that has a different shade of meaning. The many words for dogs have a spectrum of implications regarding the dog's training, obedience, or expected role, and may even make a statement about the social status of its owner ("lap dog" versus "cur"). Even synonyms have different connotations: slender, thin, skinny may each convey different images to the reader's mind. The writer should choose the connotation, positive, negative, or neutral, that supports the mood. Writing for the learned, connotation may involve etymology or make reference to classic works. In schoolbooks, awareness of connotation can avoid attracting extraneous ideas (as when writing "Napoleon was a bigger influence than Frederick the Great on world history" provokes thoughts of Napoleon's physical stature). In encyclopedias, words should connote authority and dispassion; the writer should avoid words whose connotations suggest bias, such as pejorative words. [edit]Punctuation Punctuation is now so standardized that it rarely is a factor in a writer's style. The same is true for gratuitous changes to spelling and grammar, unless the goal is to represent a regional or ethnic dialect in which such changes are customary. [edit]Clichés Some figures of speech are phrases that briefly describe a complicated concept through connotation. However, some of these phrases are used so frequently that they have lost their novelty, sincerity, and perhaps even their meaning. They are disparagingly referred to as clichés or bromides. Whether a given expression has fallen into this category is a matter of opinion. A reader who knows, or is a member of, the target audience may have a strong opinion that one or the other alternative seems better-written. [edit]Bibliography
Fawcett, Susan (2004). Evergreen: A Guide to Writing With Readings. Houghton Mifflin Company. ISBN 0-618-27387-5. Polking, Kirk (1990). Writing A to Z. Writer's Digest Books. ISBN 0-89879-556-7. Rozakis, Laurie (2003). The Complete Idiot's Guide to Grammar and Style, 2nd Edition. Alpha. ISBN 1-59257-115-8 Shaw, Harry (1965). A Complete Course in Freshman English. Harper & Row. Strunk, William and E. B. White. (1959). The Elements of Style. MacMillan Publishing Co. ISBN 0-02-418220-6. Watkins, Floyd C., William B. Dillingham, and Edwin T. Martin. (1974). Practical English Handbook. Houghton Mifflin Company. ISBN 0-395-16822-8. Williams, Joseph (2007) Style: Lessons in Clarity and Grace. Pearson Longman ISBN 032-147935-1 ISBN 978-032-147935-8 Zinsser, William (2001). On Writing Well. Quill. ISBN 0-06-000664-1.
From Wikipedia, the free encyclopedia For other uses, see Fish (disambiguation).
Fish Fossil range: Ordovician–Neogene PreЄЄOSDCPTJKPgN
A giant grouper at the Georgia Aquarium, seen swimming among schools of other fish
The ornate red lionfish as seen from a head-on view Scientific classification Kingdom: Animalia Phylum: Chordata (unranked) Craniata Included groups Jawless fish †Armoured fish Cartilaginous fish Ray-finned fish Lobe-finned fishes Excluded groups Tetrapods Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate (or craniate) animals that lacks limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups. Most fish are "cold-blooded", or ectothermic, allowing their body temperatures to vary as ambient temperatures change, though some of the large active swimmers like white shark and tuna can hold a higher core temperature.[1][2] Fish are abundant in most bodies of water. They can be found in nearly all aquatic environments, from high mountain streams (e.g., char and gudgeon) to the abyssal and even hadal depths of the deepest oceans (e.g., gulpers and anglerfish). At 32,000 species, fish exhibit greater species diversity than any other class of vertebrates.[3] Fish, especially as food, are an important resource worldwide. Commercial and subsistence fishers hunt fish in wild fisheries (see fishing) or farm them in ponds or in cages in the ocean (see aquaculture). They are also caught by recreational fishers, kept as pets, raised by fishkeepers, and exhibited in public aquaria. Fish have had a role in culture through the ages, serving as deities, religious symbols, and as the subjects of art, books and movies. Because the term "fish" is defined negatively, and excludes the tetrapods (i.e., the amphibians, reptiles, birds and mammals) which descend from within the same ancestry, it is paraphyletic, and is not considered a proper grouping in systematic biology. The traditional term pisces (also ichthyes) is considered a typological, but not a phylogenetic classification. Contents [hide] 1 Diversity of fish 2 Taxonomy 3 Anatomy 3.1 Respiration 3.2 Circulation 3.3 Digestion 3.4 Excretion 3.5 Scales 3.6 Sensory and nervous system 3.6.1 Central nervous system 3.6.2 Sense organs 3.6.2.1 Vision 3.6.3 Capacity for pain 3.7 Muscular system 3.8 Homeothermy 3.9 Reproductive system 3.9.1 Organs 3.9.2 Reproductive method 3.10 Immune system 4 Diseases 5 Evolution 6 Conservation 6.1 Overfishing 6.2 Habitat destruction 6.3 Exotic species 7 Importance to humans 7.1 Aquarium collecting 7.2 Economic importance 7.3 Recreation 7.4 Culture 8 Terminology 8.1 Shoal or school? 8.2 Fish or fishes? 9 See also 10 Notes 11 References 12 External links Diversity of fish
Fish come in many shapes and sizes. This is a sea dragon, a close relative of the seahorse. Their leaf-like appendages enable them to blend in with floating seaweed. Main article: Diversity of fish The term "fish" most precisely describes any non-tetrapod craniate (i.e. an animal with a skull and in most cases a backbone) that has gills throughout life and whose limbs, if any, are in the shape of fins.[4] Unlike groupings such as birds or mammals, fish are not a single clade but a paraphyletic collection of taxa, including hagfishes, lampreys, sharks and rays, ray-finned fish, coelacanths, and lungfish.[5][6] Indeed, lungfish and coelacanths are closer relatives of tetrapods (such as mammals, birds, amphibians, etc.) than of other fish such as ray-finned fish or sharks, so the last common ancestor of all fish is also an ancestor to tetrapods. As paraphyletic groups are no longer recognised in modern systematic biology, the use of the term "fish" as a biological group must be avoided. Many types of aquatic animals commonly referred to as "fish" are not fish in the sense given above; examples include shellfish, cuttlefish, starfish, crayfish and jellyfish. In earlier times, even biologists did not make a distinction – sixteenth century natural historians classified also seals, whales, amphibians, crocodiles, even hippopotamuses, as well as a host of aquatic invertebrates, as fish.[7] However, according the definition above, all mammals, including Cetaceans like Whales and Dolphins, are not fish. In some contexts, especially in aquaculture, the true fish are referred to as finfish (or fin fish) to distinguish them from these other animals. A typical fish is ectothermic, has a streamlined body for rapid swimming, extracts oxygen from water using gills or uses an accessory breathing organ to breathe atmospheric oxygen, has two sets of paired fins, usually one or two (rarely three) dorsal fins, an anal fin, and a tail fin, has jaws, has skin that is usually covered with scales, and lays eggs. Each criterion has exceptions. Tuna, swordfish, and some species of sharks show some warm-blooded adaptations—they can heat their bodies significantly above ambient water temperature.[5] Streamlining and swimming performance varies from fish such as tuna, salmon, and jacks that can cover 10–20 body-lengths per second to species such as eels and rays that swim no more than 0.5 body-lengths per second.[5] Many groups of freshwater fish extract oxygen from the air as well as from the water using a variety of different structures. Lungfish have paired lungs similar to those of tetrapods, gouramis have a structure called the labyrinth organ that performs a similar function, while many catfish, such as Corydoras extract oxygen via the intestine or stomach.[8] Body shape and the arrangement of the fins is highly variable, covering such seemingly un-fishlike forms as seahorses, pufferfish, anglerfish, and gulpers. Similarly, the surface of the skin may be naked (as in moray eels), or covered with scales of a variety of different types usually defined as placoid (typical of sharks and rays), cosmoid (fossil lungfish and coelacanths), ganoid (various fossil fish but also living gars and bichirs), cycloid, and ctenoid (these last two are found on most bony fish).[9] There are even fish that live mostly on land. Mudskippers feed and interact with one another on mudflats and go underwater to hide in their burrows.[10] The catfish Phreatobius cisternarum lives in underground, phreatic habitats, and a relative lives in waterlogged leaf litter.[11][12] Fish range in size from the huge 16-metre (52 ft) whale shark to the tiny 8-millimetre (0.3 in) stout infantfish. Fish species diversity is roughly divided equally between marine (oceanic) and freshwater ecosystems. Coral reefs in the Indo-Pacific constitute the center of diversity for marine fishes, whereas continental freshwater fishes are most diverse in large river basins of tropical rainforests, especially the Amazon, Congo, and Mekong basins. More than 5,600 fish species inhabit Neotropical freshwaters alone, such that Neotropical fishes represent about 10% of all vertebrate species on the Earth. Taxonomy
Fish are a paraphyletic group: that is, any clade containing all fish also contains the tetrapods, which are not fish. For this reason, groups such as the "Class Pisces" seen in older reference works are no longer used in formal classifications. Traditional classification divide fish into three extant classes, and with extinct forms sometimes classified within the tree, sometimes as their own classes:[13][14] Class Agnatha (Jawless fish) Subclass Cyclostomata (hagfish and lampreys) Subclass Ostracodermi (armoured jawless fish) † Class Chondrichthyes (cartilaginous fish) Subclass Elasmobranchii (sharks and rayes) Subclass Holocephali (chimaeras and extinct relatives) Class Placodermi (armoured fish) † Class Acanthodii ("spiny sharks", sometimes classified under bony fishes)† Class Osteichthyes (bony fish) Subclass Actinopterygii (ray finned fishes) Subclass Sarcopterygii (fleshy finned fishes, ancestors of tetrapods) The above scheme is the one most commonly encountered in non-specialist and general works. Many of the above groups are paraphyletic, in that they have given rise to successive groups: Agnathans are ancestral to Chondrichthyes, who again have given rise to Acanthodiians, the ancestors of Osteichthyes. With the arrival of phylogenetic nomenclature, the fishes has been spit up into a more detailed scheme, with the following major groups: Class Myxini (hagfish) Class Pteraspidomorphi † (early jawless fish) Class Thelodonti † Class Anaspida † Class Petromyzontida or Hyperoartia Petromyzontidae (lampreys) Class Conodonta (conodonts) † Class Cephalaspidomorphi † (early jawless fish) (unranked) Galeaspida † (unranked) Pituriaspida † (unranked) Osteostraci † Infraphylum Gnathostomata (jawed vertebrates) Class Placodermi † (armoured fish) Class Chondrichthyes (cartilaginous fish) Class Acanthodii † (spiny sharks) Superclass Osteichthyes (bony fish) Class Actinopterygii (ray-finned fish) Subclass Chondrostei Order Acipenseriformes (sturgeons and paddlefishes) Order Polypteriformes (reedfishes and bichirs). Subclass Neopterygii Infraclass Holostei (gars and bowfins) Infraclass Teleostei (many orders of common fish) Class Sarcopterygii (lobe-finned fish) Subclass Coelacanthimorpha (coelacanths) Subclass Dipnoi (lungfish) † - indicates extinct taxon Some palaeontologists contend that because Conodonta are chordates, they are primitive fish. For a fuller treatment of this taxonomy, see the vertebrate article. The position of hagfish in the phylum chordata is not settled. Phylogenetic research in 1998 and 1999 supported the idea that the hagfish and the lampreys form a natural group, the Cyclostomata, that is a sister group of the Gnathostomata.[15][16] The various fish groups account for more than half of vertebrate species. There are almost 28,000 known extant species, of which almost 27,000 are bony fish, with 970 sharks, rays, and chimeras and about 108 hagfish and lampreys.[17] A third of these species fall within the nine largest families; from largest to smallest, these families are Cyprinidae, Gobiidae, Cichlidae, Characidae, Loricariidae, Balitoridae, Serranidae, Labridae, and Scorpaenidae. About 64 families are monotypic, containing only one species. The final total of extant species may grow to exceed 32,500.[18] Anatomy
Main article: Fish anatomy
The anatomy of Lampanyctodes hectoris (1) – operculum (gill cover), (2) – lateral line, (3) – dorsal fin, (4) – fat fin, (5) – caudal peduncle, (6) – caudal fin, (7) – anal fin, (8) – photophores, (9) – pelvic fins (paired), (10) – pectoral fins (paired) Respiration Most fish exchange gases using gills on either side of the pharynx. Gills consist of threadlike structures called filaments. Each filament contains a capillary network that provides a large surface area for exchanging oxygen and carbon dioxide. Fish exchange gases by pulling oxygen-rich water through their mouths and pumping it over their gills. In some fish, capillary blood flows in the opposite direction to the water, causing countercurrent exchange. The gills push the oxygen-poor water out through openings in the sides of the pharynx. Some fish, like sharks and lampreys, possess multiple gill openings. However, bony fish have a single gill opening on each side. This opening is hidden beneath a protective bony cover called an operculum. Juvenile bichirs have external gills, a very primitive feature that they share with larval amphibians. Fish from multiple groups can live out of the water for extended time periods. Amphibious fish such as the mudskipper can live and move about on land for up to several days, or live in stagnant or otherwise oxygen depleted water. Many such fish can breathe air via a variety of mechanisms. The skin of anguillid eels may absorb oxygen directly. The buccal cavity of the electric eel may breathe air. Catfish of the families Loricariidae, Callichthyidae, and Scoloplacidae absorb air through their digestive tracts.[19] Lungfish, with the exception of the Australian lungfish, and bichirs have paired lungs similar to those of tetrapods and must surface to gulp fresh air through the mouth and pass spent air out through the gills. Gar and bowfin have a vascularized swim bladder that functions in the same way. Loaches, trahiras, and many catfish breathe by passing air through the gut. Mudskippers breathe by absorbing oxygen across the skin (similar to frogs). A number of fish have evolved so-called accessory breathing organs that extract oxygen from the air. Labyrinth fish (such as gouramis and bettas) have a labyrinth organ above the gills that performs this function. A few other fish have structures resembling labyrinth organs in form and function, most notably snakeheads, pikeheads, and the Clariidae catfish family. Breathing air is primarily of use to fish that inhabit shallow, seasonally variable waters where the water's oxygen concentration may seasonally decline. Fish dependent solely on dissolved oxygen, such as perch and cichlids, quickly suffocate, while air-breathers survive for much longer, in some cases in water that is little more than wet mud. At the most extreme, some air-breathing fish are able to survive in damp burrows for weeks without water, entering a state of aestivation (summertime hibernation) until water returns.
Tuna gills inside of the head. The fish head is oriented snout-downwards, with the view looking towards the mouth. Air breathing fish can be divided into obligate air breathers and facultative air breathers. Obligate air breathers, such as the African lungfish, must breathe air periodically or they suffocate. Facultative air breathers, such as the catfish Hypostomus plecostomus, only breathe air if they need to and will otherwise rely on their gills for oxygen. Most air breathing fish are facultative air breathers that avoid the energetic cost of rising to the surface and the fitness cost of exposure to surface predators.[19] Circulation Fish have a closed-loop circulatory system. The heart pumps the blood in a single loop throughout the body. In most fish, the heart consists of four parts, including two chambers and an entrance and exit.[20] The first part is the sinus venosus, a thin-walled sac that collects blood from the fish's veins before allowing it to flow to the second part, the atrium, which is a large muscular chamber. The atrium serves as a one-way antechamber, sends blood to the third part, ventricle. The ventricle is another thick-walled, muscular chamber and it pumps the blood, first to the fourth part, bulbus arteriosus, a large tube, and then out of the heart. The bulbus arteriosus connects to the aorta, through which blood flows to the gills for oxygenation. Digestion Jaws allow fish to eat a wide variety of food, including plants and other organisms. Fish ingest food through the mouth and break it down in the esophagus. In the stomach, food is further digested and, in many fish, processed in finger-shaped pouches called pyloric caeca, which secrete digestive enzymes and absorb nutrients. Organs such as the liver and pancreas add enzymes and various chemicals as the food moves through the digestive tract. The intestine completes the process of digestion and nutrient absorption. Excretion As with many aquatic animals, most fish release their nitrogenous wastes as ammonia. Some of the wastes diffuse through the gills. Blood wastes are filtered by the kidneys. Saltwater fish tend to lose water because of osmosis. Their kidneys return water to the body. The reverse happens in freshwater fish: they tend to gain water osmotically. Their kidneys produce dilute urine for excretion. Some fish have specially adapted kidneys that vary in function, allowing them to move from freshwater to saltwater. Scales Main article: Scale (zoology)#Fish scales The scales of fish originate from the mesoderm (skin); they may be similar in structure to teeth. Sensory and nervous system
Dorsal view of the brain of the rainbow trout Central nervous system Fish typically have quite small brains relative to body size compared with other vertebrates, typically one-fifteenth the brain mass of a similarly sized bird or mammal.[21] However, some fish have relatively large brains, most notably mormyrids and sharks, which have brains about as massive relative to body weight as birds and marsupials.[22] Fish brains are divided into several regions. At the front are the olfactory lobes, a pair of structures that receive and process signals from the nostrils via the two olfactory nerves.[21] The olfactory lobes are very large in fish that hunt primarily by smell, such as hagfish, sharks, and catfish. Behind the olfactory lobes is the two-lobed telencephalon, the structural equivalent to the cerebrum in higher vertebrates. In fish the telencephalon is concerned mostly with olfaction.[21] Together these structures form the forebrain. Connecting the forebrain to the midbrain is the diencephalon (in the diagram, this structure is below the optic lobes and consequently not visible). The diencephalon performs functions associated with hormones and homeostasis.[21] The pineal body lies just above the diencephalon. This structure detects light, maintains circadian rhythms, and controls color changes.[21] The midbrain or mesencephalon contains the two optic lobes. These are very large in species that hunt by sight, such as rainbow trout and cichlids.[21] The hindbrain or metencephalon is particularly involved in swimming and balance.[21] The cerebellum is a single-lobed structure that is typically the biggest part of the brain.[21] Hagfish and lampreys have relatively small cerebellae, while the mormyrid cerebellum is massive and apparently involved in their electrical sense.[21] The brain stem or myelencephalon is the brain's posterior.[21] As well as controlling some muscles and body organs, in bony fish at least, the brain stem governs respiration and osmoregulation.[21] Sense organs Most fish possess highly developed sense organs. Nearly all daylight fish have color vision that is at least as good as a human's (see vision in fishes). Many fish also have chemoreceptors that are responsible for extraordinary senses of taste and smell. Although they have ears, many fish may not hear very well. Most fish have sensitive receptors that form the lateral line system, which detects gentle currents and vibrations, and senses the motion of nearby fish and prey.[23] Some fish, such as catfish and sharks, have organs that detect weak electric currents on the order of millivolt.[24] Other fish, like the South American electric fishes Gymnotiformes, can produce weak electric currents, which they use in navigation and social communication. Fish orient themselves using landmarks and may use mental maps based on multiple landmarks or symbols. Fish behavior in mazes reveals that they possess spatial memory and visual discrimination.[25] Vision Main article: Vision in fishes Vision is an important sensory system for most species of fish. Fish eyes are similar to those of terrestrial vertebrates like birds and mammals, but have a more spherical lens. Their retinas generally have both rod cells and cone cells (for scotopic and photopic vision), and most species have colour vision. Some fish can see ultraviolet and some can see polarized light. Amongst jawless fish, the lamprey has well-developed eyes, while the hagfish has only primitive eyespots.[26] Fish vision shows adaptation to their visual environment, for example deep sea fishes have eyes suited to the dark environment. Capacity for pain Further information: Pain in fish Experiments done by William Tavolga provide evidence that fish have pain and fear responses. For instance, in Tavolga’s experiments, toadfish grunted when electrically shocked and over time they came to grunt at the mere sight of an electrode.[27] In 2003, Scottish scientists at the University of Edinburgh and the Roslin Institute concluded that rainbow trout exhibit behaviors often associated with pain in other animals. Bee venom and acetic acid injected into the lips resulted in fish rocking their bodies and rubbing their lips along the sides and floors of their tanks, which the researchers concluded were attempts to relieve pain, similar to what mammals would do.[28][29][30] Neurons fired in a pattern resembling human neuronal patterns.[30] Professor James D. Rose of the University of Wyoming claimed the study was flawed since it did not provide proof that fish possess "conscious awareness, particularly a kind of awareness that is meaningfully like ours".[31] Rose argues that since fish brains are so different from human brains, fish are probably not conscious in the manner humans are, so that reactions similar to human reactions to pain instead have other causes. Rose had published a study a year earlier arguing that fish cannot feel pain because their brains lack a neocortex.[32] However, animal behaviorist Temple Grandin argues that fish could still have consciousness without a neocortex because "different species can use different brain structures and systems to handle the same functions."[30] Animal welfare advocates raise concerns about the possible suffering of fish caused by angling. Some countries, such as Germany have banned specific types of fishing, and the British RSPCA now formally prosecutes individuals who are cruel to fish.[33] Muscular system Main article: Fish locomotion
Swim bladder of a Rudd (Scardinius erythrophthalmus) Most fish move by alternately contracting paired sets of muscles on either side of the backbone. These contractions form S-shaped curves that move down the body. As each curve reaches the back fin, backward force is applied to the water, and in conjunction with the fins, moves the fish forward. The fish's fins function like an airplane's flaps. Fins also increase the tail's surface area, increasing speed. The streamlined body of the fish decreases the amount of friction from the water. Since body tissue is denser than water, fish must compensate for the difference or they will sink. Many bony fish have an internal organ called a swim bladder that adjusts their buoyancy through manipulation of gases.
A 3-tonne (3.0-long-ton; 3.3-short-ton) great white shark off Isla Guadalupe Homeothermy Although most fish are exclusively ectothermic, there are exceptions. Certain species of fish maintain elevated body temperatures. Endothermic teleosts (bony fish) are all in the suborder Scombroidei and include the billfishes, tunas, and one species of "primitive" mackerel (Gasterochisma melampus). All sharks in the family Lamnidae – shortfin mako, long fin mako, white, porbeagle, and salmon shark – are endothermic, and evidence suggests the trait exists in family Alopiidae (thresher sharks). The degree of endothermy varies from the billfish, which warm only their eyes and brain, to bluefin tuna and porbeagle sharks who maintain body temperatures elevated in excess of 20 °C above ambient water temperatures. See also gigantothermy. Endothermy, though metabolically costly, is thought to provide advantages such as increased muscle strength, higher rates of central nervous system processing, and higher rates of digestion. Reproductive system Further information: Spawn (biology) Organs
Organs: 1. Liver, 2. Gas bladder, 3. Roe, 4. Pyloric caeca, 5. Stomach, 6. Intestine Fish reproductive organs include testes and ovaries. In most species, gonads are paired organs of similar size, which can be partially or totally fused.[34] There may also be a range of secondary organs that increase reproductive fitness. In terms of spermatogonia distribution, the structure of teleosts testes has two types: in the most common, spermatogonia occur all along the seminiferous tubules, while in Atherinomorph fish they are confined to the distal portion of these structures. Fish can present cystic or semi-cystic spermatogenesis in relation to the release phase of germ cells in cysts to the seminiferous tubules lumen.[34] Fish ovaries may be of three types: gymnovarian, secondary gymnovarian or cystovarian. In the first type, the oocytes are released directly into the coelomic cavity and then enter the ostium, then through the oviduct and are eliminated. Secondary gymnovarian ovaries shed ova into the coelom from which they go directly into the oviduct. In the third type, the oocytes are conveyed to the exterior through the oviduct.[35] Gymnovaries are the primitive condition found in lungfish, sturgeon, and bowfin. Cystovaries characterize most teleosts, where the ovary lumen has continuity with the oviduct.[34] Secondary gymnovaries are found in salmonids and a few other teleosts. Oogonia development in teleosts fish varies according to the group, and the determination of oogenesis dynamics allows the understanding of maturation and fertilization processes. Changes in the nucleus, ooplasm, and the surrounding layers characterize the oocyte maturation process.[34] Postovulatory follicles are structures formed after oocyte release; they do not have endocrine function, present a wide irregular lumen, and are rapidly reabsorbed in a process involving the apoptosis of follicular cells. A degenerative process called follicular atresia reabsorbs vitellogenic oocytes not spawned. This process can also occur, but less frequently, in oocytes in other development stages.[34] Some fish are hermaphrodites, having both testes and ovaries either at different phases in their life cycle or, as in hamlets, have them simultaneously. Reproductive method Over 97% of all known fish are oviparous,[36] that is, the eggs develop outside the mother's body. Examples of oviparous fish include salmon, goldfish, cichlids, tuna, and eels. In the majority of these species, fertilisation takes place outside the mother's body, with the male and female fish shedding their gametes into the surrounding water. However, a few oviparous fish practice internal fertilization, with the male using some sort of intromittent organ to deliver sperm into the genital opening of the female, most notably the oviparous sharks, such as the horn shark, and oviparous rays, such as skates. In these cases, the male is equipped with a pair of modified pelvic fins known as claspers. Marine fish can produce high numbers of eggs which are often released into the open water column. The eggs have an average diameter of 1 millimetre (0.039 in).
Egg of lamprey
Egg of catshark (mermaids' purse)
Egg of bullhead shark
Egg of chimaera
An example of zooplankton The newly hatched young of oviparous fish are called larvae. They are usually poorly formed, carry a large yolk sac (for nourishment) and are very different in appearance from juvenile and adult specimens. The larval period in oviparous fish is relatively short (usually only several weeks), and larvae rapidly grow and change appearance and structure (a process termed metamorphosis) to become juveniles. During this transition larvae must switch from their yolk sac to feeding on zooplankton prey, a process which depends on typically inadequate zooplankton density, starving many larvae. In ovoviviparous fish the eggs develop inside the mother's body after internal fertilization but receive little or no nourishment directly from the mother, depending instead on the yolk. Each embryo develops in its own egg. Familiar examples of ovoviviparous fish include guppies, angel sharks, and coelacanths. Some species of fish are viviparous. In such species the mother retains the eggs and nourishes the embryos. Typically, viviparous fish have a structure analogous to the placenta seen in mammals connecting the mother's blood supply with that of the embryo. Examples of viviparous fish include the surf-perches, splitfins, and lemon shark. Some viviparous fish exhibit oophagy, in which the developing embryos eat other eggs produced by the mother. This has been observed primarily among sharks, such as the shortfin mako and porbeagle, but is known for a few bony fish as well, such as the halfbeak Nomorhamphus ebrardtii.[37] Intrauterine cannibalism is an even more unusual mode of vivipary, in which the largest embryos eat weaker and smaller siblings. This behavior is also most commonly found among sharks, such as the grey nurse shark, but has also been reported for Nomorhamphus ebrardtii.[37] Aquarists commonly refer to ovoviviparous and viviparous fish as livebearers. Immune system Immune organs vary by type of fish.[38] In the jawless fish (lampreys and hagfish), true lymphoid organs are absent. These fish rely on regions of lymphoid tissue within other organs to produce immune cells. For example, erythrocytes, macrophages and plasma cells are produced in the anterior kidney (or pronephros) and some areas of the gut (where granulocytes mature.) They resemble primitive bone marrow in hagfish. Cartilaginous fish (sharks and rays) have a more advanced immune system. They have three specialized organs that are unique to chondrichthyes; the epigonal organs (lymphoid tissue similar to mammalian bone) that surround the gonads, the Leydig's organ within the walls of their esophagus, and a spiral valve in their intestine. These organs house typical immune cells (granulocytes, lymphocytes and plasma cells). They also possess an identifiable thymus and a well-developed spleen (their most important immune organ) where various lymphocytes, plasma cells and macrophages develop and are stored. Chondrostean fish (sturgeons, paddlefish and bichirs) possess a major site for the production of granulocytes within a mass that is associated with the meninges (membranes surrounding the central nervous system.) Their heart is frequently covered with tissue that contains lymphocytes, reticular cells and a small number of macrophages. The chondrostean kidney is an important hemopoietic organ; where erythrocytes, granulocytes, lymphocytes and macrophages develop. Like chondrostean fish, the major immune tissues of bony fish (or teleostei) include the kidney (especially the anterior kidney), which houses many different immune cells.[39] In addition, teleost fish possess a thymus, spleen and scattered immune areas within mucosal tissues (e.g. in the skin, gills, gut and gonads). Much like the mammalian immune system, teleost erythrocytes, neutrophils and granulocytes are believed to reside in the spleen whereas lymphocytes are the major cell type found in the thymus.[40][41] In 2006, a lymphatic system similar to that in mammals was described in one species of teleost fish, the zebrafish. Although not confirmed as yet, this system presumably will be where naive (unstimulated) T cells accumulate while waiting to encounter an antigen.[42] Diseases
Main article: Fish diseases and parasites Like other animals, fish suffer from diseases and parasites. To prevent disease they have a variety of defenses. Non-specific defenses include the skin and scales, as well as the mucus layer secreted by the epidermis that traps and inhibits the growth of microorganisms. If pathogens breach these defenses, fish can develop an inflammatory response that increases blood flow to the infected region and delivers white blood cells that attempt to destroy pathogens. Specific defenses respond to particular pathogens recognised by the fish's body, i.e., an immune response.[43] In recent years, vaccines have become widely used in aquaculture and also with ornamental fish, for example furunculosis vaccines in farmed salmon and koi herpes virus in koi.[44][45] Some species use cleaner fish to remove external parasites. The best known of these are the Bluestreak cleaner wrasses of the genus Labroides found on coral reefs in the Indian and Pacific Oceans. These small fish maintain so-called "cleaning stations" where other fish congregate and perform specific movements to attract the attention of the cleaners.[46] Cleaning behaviors have been observed in a number of fish groups, including an interesting case between two cichlids of the same genus, Etroplus maculatus, the cleaner, and the much larger Etroplus suratensis.[47] Evolution
See also: prehistoric fish
Outdated evolutionary view of continual gradation (animation)
Dunkleosteus was a gigantic, 10 meter (33 ft) long prehistoric fish. Fish do not represent a monophyletic group, and therefore the "evolution of fish" is not studied as a single event.[49] Proliferation of fish was apparently due to the hinged jaw, because jawless fish left very few descendants.[50] Lampreys may approximate pre-jawed fish. The first jaws are found in Placodermi fossils. It is unclear if the advantage of a hinged jaw is greater biting force, improved respiration, or a combination of factors. Fish may have evolved from a creature similar to a coral-like Sea squirt, whose larvae resemble primitive fish in important ways. The first ancestors of fish may have kept the larval form into adulthood (as some sea squirts do today), although perhaps the reverse is the case. Conservation
From Wikipedia, the free encyclopedia (Redirected from Respiratory) See also: Respiratory tract Respiratory
A complete, schematic view of the human respiratory system with their parts and functions. Latin systema respiratorium The respiratory system is the anatomical system of an organism that introduces respiratory gases to the interior and performs gas exchange. In humans and other mammals, the anatomical features of the respiratory system include airways, lungs, and the respiratory muscles. Molecules of oxygen and carbon dioxide are passively exchanged, by diffusion, between the gaseous external environment and the blood. This exchange process occurs in the alveolar region of the lungs.[1] Other animals, such as insects, have respiratory systems with very simple anatomical features, and in amphibians even the skin plays a vital role in gas exchange. Plants also have respiratory systems but the directionality of gas exchange can be opposite to that in animals. The respiratory system in plants also includes anatomical features such as holes on the undersides of leaves known as stomata.[2] Contents [hide] 1 Comparative anatomy and physiology 1.1 Horses 1.2 Elephants 1.3 Birds 1.4 Reptiles 1.5 Amphibians 1.6 Fish 2 Anatomy in invertebrates 2.1 Insects 2.2 Mollusks 3 Physiology in mammals 3.1 Ventilation 3.1.1 Control 3.1.2 Inhalation 3.1.3 Exhalation 3.2 Gas exchange 3.3 Non-respiratory functions 3.4 Lung Defense Mechanisms 3.5 Metabolic & Endocrine Functions of the Lungs 3.5.1 Vocalization 3.5.2 Temperature control 3.5.3 Coughing and sneezing 4 Development in People 4.1 Humans and mammals 5 Disease 6 Plants 7 References 8 External links [edit]Comparative anatomy and physiology
[edit]Horses Horses are obligate nasal breathers which means that they are different from many other mammals because they do not have the option of breathing through their mouths and must take in oxygen through their noses. [edit]Elephants The elephant is the only animal known to have no pleural space. Rather, the parietal and visceral pleura are both composed of dense connective tissue and joined to each other via loose connective tissue.[3] This lack of a pleural space, along with an unusually thick diaphragm, are thought to be evolutionary adaptations allowing the elephant to remain underwater for long periods of time while breathing through its trunk which emerges as a snorkel.[4] [edit]Birds The respiratory system of birds differs significantly from that found in mammals, containing unique anatomical features such as air sacs. The lungs of birds also do not have the capacity to inflate as birds lack a diaphragm and a pleural cavity. Gas exchange in birds occurs between air capillaries and blood capillaries, rather than in alveoli. See Avian respiratory system for a detailed description of these and other features. [edit]Reptiles The anatomical structure of the lungs is less complex in reptiles than in mammals, with reptiles lacking the very extensive airway tree structure found in mammalian lungs. Gas exchange in reptiles still occurs in alveoli however, reptiles do not possess a diaphragm. Thus, breathing occurs via a change in the volume of the body cavity which is controlled by contraction of intercostal muscles in all reptiles except turtles. In turtles, contraction of specific pairs of flank muscles governs inspiration or expiration.[5] See also reptiles for more detailed descriptions of the respiratory system in these animals. [edit]Amphibians Both the lungs and the skin serve as respiratory organs in amphibians. The skin of these animals is highly vascularized and moist, with moisture maintained via secretion of mucus from specialized cells. While the lungs are of primary importance to breathing control, the skin's unique properties aid rapid gas exchange when amphibians are submerged in oxygen-rich water.[6] [edit]Fish In most fish respiration takes place through gills. (See also aquatic respiration.) Lungfish, however, do possess one or two lungs. The labyrinth fish have developed a special organ that allows them to take advantage of the oxygen of the air. [edit]Anatomy in invertebrates
[edit]Insects Air enters the respiratory systems of most insects through a series of external openings called spiracles. These external openings, which act as muscular valves in some insects, lead to the internal respiratory system, a densely networked array of tubes called tracheae. The scientific tracheal system within an individual is composed of interconnecting transverse and longitudinal tracheae which maintain equivalent pressure throughout the system. These tracheae branch repeatedly, eventually forming tracheoles, which are blind-ended, water-filled compartments only one micrometer in diameter.[7] It is at this level of the tracheoles that oxygen is delivered to the cells for respiration. The trachea are water-filled due to the permeable membrane of the surrounding tissues. During exercise, the water level retracts due to the increase in concentration of lactic acid in the muscle cells. This lowers the water potential and the water is drawn back into the cells via osmosis and air is brought closer to the muscle cells. The diffusion pathway is then reduced and gases can be transferred more easily. Insects were once believed to exchange gases with the environment continuously by the simple diffusion of gases into the tracheal system. More recently, however, large variation in insect ventilatory patterns have been documented and insect respiration appears to be highly variable. Some small insects do demonstrate continuous respiration and may lack muscular control of the spiracles. Others, however, utilize muscular contraction of the abdomen along with coordinated spiracle contraction and relaxation to generate cyclical gas exchange patterns and to reduce water loss into the atmosphere. The most extreme form of these patterns is termed discontinuous gas exchange cycles (DGC).[8] [edit]Mollusks Mollusks generally possess gills that allow exchange of oxygen from an aqueous environment into the circulatory system. These animals also possess a heart that pumps blood which contains hemocyaninine as its oxygen-capturing molecule. Hence, this respiratory system is similar to that of vertebrate fish. The respiratory system of gastropods can include either gills or a lung. [edit]Physiology in mammals
For more detailed descriptions see also Respiratory physiology or Respiration. [edit]Ventilation In respiratory physiology, ventilation (or ventilation rate) is the rate at which gas enters or leaves the lung. It is categorised under the following definitions: Measurement Equation Description Minute ventilation tidal volume * respiratory rate[1][2] the total volume of gas entering the lungs per minute. Alveolar ventilation (tidal volume - dead space) * respiratory rate [1] the volume of gas per unit time that reaches the alveoli, the respiratory portions of the lungs where gas exchange occurs. Dead space ventilation dead space * respiratory rate[3] the volume of gas per unit time that does not reach these respiratory portions, but instead remains in the airways (trachea, bronchi, etc.). [edit]Control Ventilation occurs under the control of the autonomic nervous system from parts of the brain stem, the medulla oblongata and the pons. This area of the brain forms the respiration regulatory center, a series of interconnected brain cells within the lower and middle brain stem which coordinate respiratory movements. The sections are the pneumotaxic center, the apneustic center, and the dorsal and ventral respiratory groups. This section is especially sensitive during infancy, and the neurons can be destroyed if the infant is dropped and/or shaken violently. The result can be death due to "shaken baby syndrome".[9] [edit]Inhalation Inhalation is initiated by the diaphragm and supported by the external intercostal muscles. Normal resting respirations are 10 to 18 breaths per minute, with a time period of 2 seconds. During vigorous inhalation (at rates exceeding 35 breaths per minute), or in approaching respiratory failure, accessory muscles of respiration are recruited for support. These consist of sternocleidomastoid, platysma, and the scalene muscles of the neck. Pectoral muscles and latissimus dorsi are also accessory muscles. Under normal conditions, the diaphragm is the primary driver of inhalation. When the diaphragm contracts, the ribcage expands and the contents of the abdomen are moved downward. This results in a larger thoracic volume and negative pressure (with respect to atmospheric pressure) inside the thorax. As the pressure in the chest falls, air moves into the conducting zone. Here, the air is filtered, warmed, and humidified as it flows to the lungs. During forced inhalation, as when taking a deep breath, the external intercostal muscles and accessory muscles aid in further expanding the thoracic cavity. During inhalation the diaphragm contracts. [edit]Exhalation Exhalation is generally a passive process; however, active or forced exhalation is achieved by the abdominal and the internal intercostal muscles. During this process air is forced or exhaled out. The lungs have a natural elasticity: as they recoil from the stretch of inhalation, air flows back out until the pressures in the chest and the atmosphere reach equilibrium.[10] During forced exhalation, as when blowing out a candle, expiratory muscles including the abdominal muscles and internal intercostal muscles, generate abdominal and thoracic pressure, which forces air out of the lungs. [edit]Gas exchange The major function of the respiratory system is gas exchange between the external environment and an organism's circulatory system. In humans and mammals, this exchange facilitates oxygenation of the blood with a concomitant removal of carbon dioxide and other gaseous metabolic wastes from the circulation. As gas exchange occurs, the acid-base balance of the body is maintained as part of homeostasis. If proper ventilation is not maintained, two opposing conditions could occur: respiratory acidosis, a life threatening condition, and respiratory alkalosis. Upon inhalation, gas exchange occurs at the alveoli, the tiny sacs which are the basic functional component of the lungs. The alveolar walls are extremely thin (approx. 0.2 micrometres). These walls are composed of a single layer of epithelial cells (type I and type II epithelial cells) close to the pulmonary capillaries which are composed of a single layer of endothelial cells. The close proximity of these two cell types allows permeability to gases and, hence, gas exchange. This whole mechanism of gas exchange is carried by the simple phenomenon of pressure difference. When the atmospheric pressure is low outside, the air from lungs flow out. When the air pressure is low inside, then the vice versa. [edit]Non-respiratory functions [edit]Lung Defense Mechanisms Airway epithelial cells can secrete a variety of molecules that aid in lung defense. Secretory immunoglobulins (IgA), collectins (including Surfactant A and D), defensins and other peptides and proteases, reactive oxygen species, and reactive nitrogen species are all generated by airway epithelial cells. These secretions can act directly as antimicrobials to help keep the airway free of infection. Airway epithelial cells also secrete a variety of chemokines and cytokines that recruit the traditional immune cells and others to site of infections. [edit]Metabolic & Endocrine Functions of the Lungs In addition to their functions in gas exchange, the lungs have a number of metabolic functions. They manufacture surfactant for local use, as noted above. They also contain a fibrinolytic system that lyses clots in the pulmonary vessels. They release a variety of substances that enter the systemic arterial blood and they remove other substances from the systemic venous blood that reach them via the pulmonary artery. Prostaglandins are removed from the circulation, but they are also synthesized in the lungs and released into the blood when lung tissue is stretched. The lungs also activate one hormone; the physiologically inactive decapeptide angiotensin I is converted to the pressor, aldosterone-stimulating octapeptide angiotensin II in the pulmonary circulation. The reaction occurs in other tissues as well, but it is particularly prominent in the lungs. Large amounts of the angiotensin-converting enzyme responsible for this activation are located on the surface of the endothelial cells of the pulmonary capillaries. The converting enzyme also inactivates bradykinin. Circulation time through the pulmonary capillaries is less than 1 s, yet 70% of the angiotensin I reaching the lungs is converted to angiotensin II in a single trip through the capillaries. Four other peptidases have been identified on the surface of the pulmonary endothelial cells. [edit]Vocalization The movement of gas through the larynx, pharynx and mouth allows humans to speak, or phonate. Vocalization, or singing, in birds occurs via the syrinx, an organ located at the base of the trachea. The vibration of air flowing across the larynx (vocal chords), in humans, and the syrinx, in birds, results in sound. Because of this, gas movement is extremely vital for communication purposes. [edit]Temperature control Panting in dogs and some other animals provides a means of controlling body temperature. This physiological response is used as a cooling mechanism. [edit]Coughing and sneezing Irritation of nerves within the nasal passages or airways, can induce coughing and sneezing. These responses cause air to be expelled forcefully from the trachea or nose, respectively. In this manner, irritants caught in the mucus which lines the respiratory tract are expelled or moved to the mouth where they can be swallowed. [edit]Development in People
[edit]Humans and mammals Further information: Development of human lung The respiratory system lies dormant in the human fetus during pregnancy. At birth, the respiratory system becomes fully functional upon exposure to air, although some lung development and growth continues throughout childhood. Pre-term birth can lead to infants with under-developed lungs. These lungs show incomplete development of the alveolar type II cells, cells that produce surfactant. The lungs of pre-term infants may not function well because the lack of surfactant leads to increased surface tension within the alveoli. Thus, many alveoli collapse such that no gas exchange can occur within some or most regions of an infant's lungs, a condition termed respiratory distress syndrome. Basic scientific experiments, carried out using cells from chicken lungs, support the potential for using steroids as a means of furthering development of type II alveolar cells.[11] In fact, once a pre-mature birth is threatened, every effort is made to delay the birth, and a series of steroid shots is frequently administered to the mother during this delay in an effort to promote lung growth.[12] [edit]Disease
Disorders of the respiratory system can be classified into four general areas: Obstructive conditions (e.g., emphysema, bronchitis, asthma) Restrictive conditions (e.g., fibrosis, sarcoidosis, alveolar damage, pleural effusion) Vascular diseases (e.g., pulmonary edema, pulmonary embolism, pulmonary hypertension) Infectious, environmental and other "diseases" (e.g., pneumonia, tuberculosis, asbestosis, particulate pollutants): Coughing is of major importance, as it is the body's main method to remove dust, mucus, saliva, and other debris from the lungs. Inability to cough can lead to infection. Deep breathing exercises may help keep finer structures of the lungs clear from particulate matter, etc. The respiratory tract is constantly exposed to microbes due to the extensive surface area, which is why the respiratory system includes many mechanisms to defend itself and prevent pathogens from entering the body. Disorders of the respiratory system are usually treated internally by a pulmonologist and Respiratory Therapist. [edit]Plants
Plants use carbon dioxide gas in the process of photosynthesis, and exhale oxygen gas as waste. The chemical equation of photosynthesis is 6 CO2 (carbon dioxide) and 6 H2O (water) and that makes 6 O2 (oxygen) and C6H12O6 (glucose). Respiration is the opposite of that. However, plants also sometimes respire as humans do, taking in oxygen and producing carbon dioxide. Plant respiration is limited by the process of diffusion. Plants take in carbon dioxide through holes on the undersides of their leaves known as stoma or pores. However, most plants require little air.[citation needed] Most plants have relatively few living cells outside of their surface because air (which is required for metabolic content) can penetrate only skin deep. However, most plants are not involved in highly aerobic activities, and thus have no need of these living cells. [edit]References
^ Haton, Anthea; Jean, Hopkins Susan, Johnson Charles William, McLaughlin Maryanna Quon Warner David, LaHart Wright, Jill D. (2009). Human Biology and Health. Englewood Cliffs,: Prentice Hall. pp. 108–118. ISBN 0-12-981176-1. ^ West, John B.. Respiratory physiology-- the essentials. Baltimore: Williams & Wilkins. pp. 1–10. ISBN 0-683-08937-4. ^ West, John B.; Ravichandran (1993). "Snorkel breathing in the elephant explains the unique anatomy of its pleura". Respiration Physiology 126 (1): 1–8. doi:10.1016/S0034-5687(01)00203-1. PMID 11311306. ^ West, John B. (2002). "Why doesn't the elephant have a pleural space?". News Physiol Sci 17: 47–50. PMID 11909991. ^ Britannica On-line Encyclopedia ^ Gottlieb, G; Jackson DC (1976). "Importance of pulmonary ventilation in respiratory control in the bullfrog". Am J Physiol 230 (3): 608–13. PMID 4976. ^ Introduction to Insect Anatomy ^ Lighton, JRB (January 1996). "Discontinuous gas exchange in insects". Annu Rev Entomology 41: 309–324. ^ *Fact sheet on Shaken Baby Syndrome ^ A simple model of how the lungs are inflated can be built from a bell jar ^ Department of Environmental Biology, University of Adelaide, Adelaide, South Australia ^ Pregnancy-facts.com
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