1.
Taxonomy (biology)
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Taxonomy is the science of defining groups of biological organisms on the basis of shared characteristics and giving names to those groups. The exact definition of taxonomy varies from source to source, but the core of the remains, the conception, naming. There is some disagreement as to whether biological nomenclature is considered a part of taxonomy, the broadest meaning of taxonomy is used here. The word taxonomy was introduced in 1813 by Candolle, in his Théorie élémentaire de la botanique, the term alpha taxonomy is primarily used today to refer to the discipline of finding, describing, and naming taxa, particularly species. In earlier literature, the term had a different meaning, referring to morphological taxonomy, ideals can, it may be said, never be completely realized. They have, however, a value of acting as permanent stimulants. Some of us please ourselves by thinking we are now groping in a beta taxonomy, turrill thus explicitly excludes from alpha taxonomy various areas of study that he includes within taxonomy as a whole, such as ecology, physiology, genetics, and cytology. He further excludes phylogenetic reconstruction from alpha taxonomy, thus, Ernst Mayr in 1968 defined beta taxonomy as the classification of ranks higher than species. This activity is what the term denotes, it is also referred to as beta taxonomy. How species should be defined in a group of organisms gives rise to practical and theoretical problems that are referred to as the species problem. The scientific work of deciding how to define species has been called microtaxonomy, by extension, macrotaxonomy is the study of groups at higher taxonomic ranks, from subgenus and above only, than species. While some descriptions of taxonomic history attempt to date taxonomy to ancient civilizations, earlier works were primarily descriptive, and focused on plants that were useful in agriculture or medicine. There are a number of stages in scientific thinking. Early taxonomy was based on criteria, the so-called artificial systems. Later came systems based on a complete consideration of the characteristics of taxa, referred to as natural systems, such as those of de Jussieu, de Candolle and Bentham. The publication of Charles Darwins Origin of Species led to new ways of thinking about classification based on evolutionary relationships and this was the concept of phyletic systems, from 1883 onwards. This approach was typified by those of Eichler and Engler, the advent of molecular genetics and statistical methodology allowed the creation of the modern era of phylogenetic systems based on cladistics, rather than morphology alone. Taxonomy has been called the worlds oldest profession, and naming and classifying our surroundings has likely been taking place as long as mankind has been able to communicate
2.
Animal
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Animals are multicellular, eukaryotic organisms of the kingdom Animalia. The animal kingdom emerged as a clade within Apoikozoa as the group to the choanoflagellates. Animals are motile, meaning they can move spontaneously and independently at some point in their lives and their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later in their lives. All animals are heterotrophs, they must ingest other organisms or their products for sustenance, most known animal phyla appeared in the fossil record as marine species during the Cambrian explosion, about 542 million years ago. Animals can be divided broadly into vertebrates and invertebrates, vertebrates have a backbone or spine, and amount to less than five percent of all described animal species. They include fish, amphibians, reptiles, birds and mammals, the remaining animals are the invertebrates, which lack a backbone. These include molluscs, arthropods, annelids, nematodes, flatworms, cnidarians, ctenophores, the study of animals is called zoology. The word animal comes from the Latin animalis, meaning having breath, the biological definition of the word refers to all members of the kingdom Animalia, encompassing creatures as diverse as sponges, jellyfish, insects, and humans. Aristotle divided the world between animals and plants, and this was followed by Carl Linnaeus, in the first hierarchical classification. In Linnaeuss original scheme, the animals were one of three kingdoms, divided into the classes of Vermes, Insecta, Pisces, Amphibia, Aves, and Mammalia. Since then the last four have all been subsumed into a single phylum, in 1874, Ernst Haeckel divided the animal kingdom into two subkingdoms, Metazoa and Protozoa. The protozoa were later moved to the kingdom Protista, leaving only the metazoa, thus Metazoa is now considered a synonym of Animalia. Animals have several characteristics that set apart from other living things. Animals are eukaryotic and multicellular, which separates them from bacteria and they are heterotrophic, generally digesting food in an internal chamber, which separates them from plants and algae. They are also distinguished from plants, algae, and fungi by lacking cell walls. All animals are motile, if only at life stages. In most animals, embryos pass through a stage, which is a characteristic exclusive to animals. With a few exceptions, most notably the sponges and Placozoa and these include muscles, which are able to contract and control locomotion, and nerve tissues, which send and process signals
3.
Parasitoid
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A parasitoid is an organism that spends a significant portion of its life history attached to or within a single host organism in a relationship where the host is ultimately killed. Thus, parasitoidy is an evolutionary strategy to typical parasitism. There are parasitoids in a variety of taxa, including microbial diseases, plants, crustaceans, insects. Especially among the Hymenoptera, ichneumons and many wasps are highly specialised for a way of life. Some parasitoidal wasps are used in biological pest control, the term parasitoid was coined in 1913 by the Swedo-Finnish writer Odo Morannal Reuter, and adopted in English by his reviewer, William Morton Wheeler. Reuter used it to describe the strategy where the parasite develops in or on the body of a single host individual, eventually killing that host, since that time, the concept has been variously generalised and widely applied. These are adaptive peaks, with possible intermediate strategies. Parasitoids eventually kill their host, typically before it can produce offspring, a nonlethal parasitic organism, especially if it is a fungus, is sometimes termed a biotroph, while a parasitoidal fungus may be called a necrotroph. Idiobiont parasitoids prevent further development of the host after initially immobilizing it, koinobiont parasitoids allow the host to continue its development while feeding upon it, and may parasitise any host life stage. There is no separation between conventional parasitism and parasitoidy. For example, blood-sucking mites sometimes overwhelm nestlings of birds such as swallows to the point that the birds cannot fledge successfully. At the opposite extreme, parasitoidy grades into predation, differences between various hunting wasps provide convenient illustrations. Predatory social wasps hunt flies, caterpillars and the like, grab them, butcher them, carry them home and feed them to their young. Similarly, some solitary wasps such as beewolves, sting prey, sometimes fatally, before saving it, usually entire, in contrast, the best-known protelean solitary hunting wasps sting prey to paralyse it before storing it for the young in the nest. Other wasps paralyse prey in the plant or other environment in which it feeds, before laying eggs nearby, some insect parasitoids lay their eggs where the larvae must locate the prey for themselves when they hatch from the eggs. Examples include flies in the families Tachinidae and Bombyliidae, often with sophisticated physiological, in another strategy, some parasitoids influence the hosts behaviour in ways that favour the propagation of the parasitoid, often at the cost of the hosts life. Similarly, as strepsipteran parasitoids of ants mature, they cause the hosts to climb high on grass stalks, positions that are risky, but favour the emergence of the strepsipterans. Other species of endoparasitoids cause infected woodlice and land Amphipoda such as Talitroides to run about in the open by day, the rabies virus affects the hosts central nervous system, eventually killing it, but perhaps helping to disseminate the virus by modifying the hosts behaviour
4.
Nematode
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The nematodes or roundworms constitute the phylum Nematoda. They are an animal phylum inhabiting a broad range of environments. Nematodes are classified along with insects and other moulting animals in the clade Ecdysozoa, Nematodes have successfully adapted to nearly every ecosystem from marine to fresh water, to soils, and from the polar regions to the tropics, as well as the highest to the lowest of elevations. They are found in part of the earths lithosphere, even at great depths below the surface of the Earth in gold mines in South Africa. They represent 90% of all animals on the ocean floor, the many parasitic forms include pathogens in most plants and animals. The location of towns would be decipherable, since for every massing of human beings there would be a corresponding massing of certain nematodes, trees would still stand in ghostly rows representing our streets and highways. In 1758, Linnaeus described some nematode genera, then included in Vermes, the name of the group Nematoda, informally called nematodes, came from Nematoidea, originally defined by Karl Rudolphi, from Ancient Greek νῆμα and -eiδἠς. It was treated as family Nematodes by Burmeister, at its origin, the Nematoidea erroneously included Nematodes and Nematomorpha, attributed by von Siebold. Along with Acanthocephala, Trematoda and Cestoidea, it formed the obsolete group Entozoa and they were also classed along with Acanthocephala in the obsolete phylum Nemathelminthes by Gegenbaur. In 1861, K. M. Diesing treated the group as order Nematoda, in 1877, the taxon Nematoidea, including the family Gordiidae, was promoted to the rank of phylum by Ray Lankester. In 1919, Nathan Cobb proposed that nematodes should be recognized alone as a phylum and he argued they should be called nema in English rather than nematodes and defined the taxon Nemates, listing Nematoidea sensu restricto as a synonym. Since Cobb was the first to all but nematodes from the group, some sources consider the valid taxon name to be Nemates or Nemata. The phylogenetic relationships of the nematodes and their close relatives among the protostomian Metazoa are unresolved, traditionally, they were held to be a lineage of their own but in the 1990s, they were proposed to form the group Ecdysozoa together with moulting animals, such as arthropods. The identity of the closest living relatives of the Nematoda has always considered to be well resolved. Morphological characters and molecular phylogenies agree with placement of the roundworms as a taxon to the parasitic Nematomorpha. Together with the Scalidophora, the Nematoida form the clade Cycloneuralia, the Cycloneuralia or the Introverta—depending on the validity of the former—are often ranked as a superphylum. Due to the lack of knowledge regarding many nematodes, their systematics is contentious, an earliest and influential classification was proposed by Chitwood and Chitwood—later revised by Chitwood—who divided the phylum into two—the Aphasmidia and the Phasmidia. These were later renamed Adenophorea and Secernentea, respectively, the Secernentea share several characteristics, including the presence of phasmids, a pair of sensory organs located in the lateral posterior region, and this was used as the basis for this division
5.
Parasitism
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In biology/ecology, parasitism is a non-mutual relationship between species, where one species, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred primarily to organisms visible to the naked eye, Parasites can be microparasites, which are typically smaller, such as protozoa, viruses, and bacteria. Examples of parasites include the plants mistletoe and cuscuta, and animals such as hookworms, unlike predators, parasites typically do not kill their host, are generally much smaller than their host, and will often live in or on their host for an extended period. Both are special cases of consumer-resource interactions, Parasites show a high degree of specialization, and reproduce at a faster rate than their hosts. Classic examples of parasitism include interactions between vertebrate hosts and tapeworms, flukes, the Plasmodium species, and fleas, parasitism differs from the parasitoid relationship in that parasitoids generally kill their hosts. Parasites reduce host biological fitness by general or specialized pathology, such as parasitic castration and impairment of secondary sex characteristics, Parasites increase their own fitness by exploiting hosts for resources necessary for their survival, e. g. food, water, heat, habitat, and transmission. Although parasitism applies unambiguously to many cases, it is part of a continuum of types of interactions between species, rather than an exclusive category, in many cases, it is difficult to demonstrate harm to the host. In others, there may be no apparent specialization on the part of the parasite, coined in English in 1611, the word parasitism comes from the Greek παρά + σιτισμός feeding, fattening. Parasites are classified based on their interactions with their hosts and on their life cycles, an obligate parasite is totally dependent on the host to complete its life cycle, while a facultative parasite is not. A direct parasite has one host while an indirect parasite has multiple hosts. For indirect parasites, there always be a definitive host. Parasites that live on the outside of the host, either on the skin or the outgrowths of the skin, are called ectoparasites and those that live inside the host are called endoparasites. Endoparasites can exist in one of two forms, intercellular parasites or intracellular parasites, intracellular parasites, such as protozoa, bacteria or viruses, tend to rely on a third organism, which is generally known as the carrier or vector. The vector does the job of transmitting them to the host, an example of this interaction is the transmission of malaria, caused by a protozoan of the genus Plasmodium, to humans by the bite of an anopheline mosquito. Those parasites living in a position, being half-ectoparasites and half-endoparasites, are called mesoparasites. An epiparasite is one that feeds on another parasite and this relationship is also sometimes referred to as hyperparasitism, exemplified by a protozoan living in the digestive tract of a flea living on a dog. Social parasites take advantage of interactions between members of social organisms such as ants, termites, and bumblebees, an extreme example of social parasitism is the ant species of Tetramorium inquilinum of the Alps, which spend their whole lives on the back of Tetramorium host ants. With tiny and deprecated bodies they have evolved for one single task, if they fall off, they most likely would not have the strength to climb back on top of another ant, and eventually they will die
6.
Arthropod
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An arthropod is an invertebrate animal having an exoskeleton, a segmented body, and jointed appendages. Arthropods form the phylum Arthropoda, which includes the insects, arachnids, myriapods, arthropods are characterized by their jointed limbs and cuticle made of chitin, often mineralised with calcium carbonate. The arthropod body plan consists of segments, each with a pair of appendages, the rigid cuticle inhibits growth, so arthropods replace it periodically by moulting. Their versatility has enabled them to become the most species-rich members of all guilds in most environments. They have over a million described species, making up more than 80% of all described living species, some of which. Arthropods range in size from the microscopic crustacean Stygotantulus up to the Japanese spider crab, arthropods primary internal cavity is a hemocoel, which accommodates their internal organs, and through which their haemolymph – analogue of blood – circulates, they have open circulatory systems. Like their exteriors, the organs of arthropods are generally built of repeated segments. Their nervous system is ladder-like, with paired ventral nerve cords running through all segments and their heads are formed by fusion of varying numbers of segments, and 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, arthropods also have a wide range of chemical and mechanical sensors, mostly based on modifications of the many setae that project through their cuticles. Aquatic species use internal or external fertilization. Almost 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 eventually undergo a total metamorphosis to produce the adult form. The level of care for hatchlings varies from nonexistent to the prolonged care provided by scorpions. The evolutionary ancestry of arthropods dates back to the Cambrian period, the group is generally regarded as monophyletic, and many analyses support the placement of arthropods with cycloneuralians in a superphylum Ecdysozoa. Overall however, the relationships of Metazoa are not yet well resolved. Likewise, the relationships between various groups are still actively debated. Arthropods contribute to the food supply both directly as food, and more importantly indirectly as pollinators of crops. Some species are known to spread disease to humans, livestock. The word arthropod comes from the Greek ἄρθρον árthron, joint, and πούς pous, i. e. foot or leg, arthropods are invertebrates with segmented bodies and jointed limbs
7.
Cockroach
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Cockroaches are insects of the order Blattodea, which also includes termites. About 30 cockroach species out of 4,600 are associated with human habitats, about four species are well known as pests. The cockroaches are an ancient group, dating back at least as far as the Carboniferous period and those early ancestors however lacked the internal ovipositors of modern roaches. They are common and hardy insects, and can tolerate a range of environments from Arctic cold to tropical heat. Some species, such as the gregarious German cockroach, have a social structure involving common shelter, social dependence, information transfer. Cockroaches have appeared in human culture since classical antiquity and they are popularly depicted as dirty pests, though the great majority of species are inoffensive and live in a wide range of habitats around the world. Cockroaches are members of the order Blattodea, which includes the termites, currently,4,600 species and over 460 genera are described worldwide. The name cockroach comes from the Spanish word for cockroach, cucaracha, transformed by 1620s English folk etymology into cock and roach. The scientific name derives from the Latin blatta, an insect that shuns the light, which in classical Latin was applied not only to cockroaches, the current catalogue of world cockroach species uses the name Blattodea for the group. Another name, Blattoptera, is sometimes used. The earliest cockroach-like fossils are from the Carboniferous period 320 million years ago, since the 19th century, scientists believed that cockroaches were an ancient group of insects that had a Devonian origin, according to one hypothesis. Fossil roachoids that lived during that time differ from modern cockroaches in having long external ovipositors and are the ancestors of mantises, as the body, hind wings and mouthparts are not preserved in fossils frequently, the relationship of these roachoids and modern cockroaches remains disputed. The first fossils of modern cockroaches with internal ovipositors appeared in the early Cretaceous, a recent phylogenetic analysis suggests that cockroaches originated at least in the Jurassic. The evolutionary relationships of the Blattodea shown in the cladogram are based on Eggleton, the cockroach families Lamproblattidae and Tryonicidae are not shown but are placed within the superfamily Blattoidea. The cockroach families Corydiidae and Ectobiidae were previously known as the Polyphagidae and Blattellidae, termites were previously regarded as a separate order Isoptera to cockroaches. However, recent genetic evidence suggests that they evolved directly from true cockroaches. This evidence supported a hypothesis suggested in 1934 that termites are closely related to the wood-eating cockroaches and this hypothesis was originally based on similarity of the symbiotic gut flagellates in termites regarded as living fossils and wood-eating cockroaches. Additional evidence emerged when F. A. McKittrick noted similar morphological characteristics between some termites and cockroach nymphs, the similarities among these cockroaches and termites have led some scientists to reclassify termites as a single family, the Termitidae, within the order Blattodea
8.
Mantidae
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Mantidae is the largest family of the order Mantodea, commonly known as praying mantises, most are tropical or subtropical. Historically, this was the family in the order. Technically, however, mantid refers only to members of the Mantidae family, many species are found in North America, the three most common being the European Mantis, the Chinese Mantis, and the Carolina Mantis. Of these, only the last is native to the continent - the European, many mantises prey on Polybia occidentalis, a swarm founding wasp. As the wasps leave the nest to forage, the mantises will prey on them, list of mantis genera and species Flower mantis Key to Mantidae Genera Tree of Life - Mantidae Naturess Best Masked Flower Image North American mantids MantisOnline. eu, All about praying mantids
9.
Orthoptera
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The Orthoptera order of insects includes the grasshoppers, crickets, cave crickets, Jerusalem crickets, katydids, weta, lubber, Acrida, and locusts. More than 27,000 species are distributed worldwide, the tympanum or ear is located in the front tibia in crickets, mole crickets, and katydids, and on the first abdominal segment in the grasshoppers and locusts. These organisms use vibrations to other individuals. Grasshoppers are able to fold their wings, placing them in the group Neoptera, the name is derived from the Greek ortho meaning straight and ptera meaning winged. Orthopterans have a cylindrical body, with hindlegs elongated for jumping. They have mandibulate mouthparts for biting and chewing and large compound eyes, the antennae have multiple joints and filiform type, and are of variable length. The first and third segments on the thorax are larger, while the segment is much smaller. They have two pairs of wings, which are held overlapping the abdomen at rest, the forewings, or tegmina, are narrower than the hindwings and hardened at the base, while the hindwing is membranous, with straight veins and numerous cross-veins. At rest, the hindwings are held folded fan-like under the forewings, the final two to three segments of the abdomen are reduced, and have single-segmented cerci. and their wing type is tegmina. Orthopteroid species have a paurometabolous lifecycle or incomplete metamorphosis, the use of sound is generally crucial in courtship, and most species have distinct songs. Most grasshoppers lay their eggs in the ground or on vegetation, the eggs hatch and the young nymphs resemble adults, but lack wings and at this stage are often called hoppers. They may often also have a different coloration from the adults. Through successive moults, the nymphs develop wings until their final moult into an adult with fully developed wings. The number of moults varies between species, growth is very variable and may take a few weeks to some months depending on food availability. The branching order of animals is fairly well understood. The suborders Caelifera and Ensifera appear to be monophyletic and the Rhaphidophoridae are a group of the Tettigoniidae. The Pyrgomorphidae are the most basal group of Caelifera, the Myrmecophilidae appear to form a clade with the Gryllotalpidae instead of with the Gryllidae. Additional work may be needed to confirm this, among the four subfamilies of Tettigoniidae, the relationships are, among six acridid subfamilies the relationships are
10.
Crustacean
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Crustaceans form a large, diverse arthropod taxon which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill, woodlice and barnacles. In other words, some crustaceans are more related to insects. The 67,000 described species range in size from Stygotantulus stocki at 0.1 mm, to the Japanese spider crab with a leg span of up to 3.8 m, like other arthropods, crustaceans have an exoskeleton, which they moult to grow. Most crustaceans are free-living aquatic animals, but some are terrestrial, some are parasitic, the group has an extensive fossil record, reaching back to the Cambrian, and includes living fossils such as Triops cancriformis, which has existed apparently unchanged since the Triassic period. More than 10 million tons of crustaceans are produced by fishery or farming for human consumption, krill and copepods are not as widely fished, but may be the animals with the greatest biomass on the planet, and form a vital part of the food chain. The scientific study of crustaceans is known as carcinology, and a scientist who works in carcinology is a carcinologist, the body of a crustacean is composed of segments, which are grouped into three regions, the cephalon or head, the thorax, and the pleon or abdomen. The head and thorax may be fused together to form a cephalothorax, the crustacean body is protected by the hard exoskeleton, which must be moulted for the animal to grow. The shell around each somite can be divided into a dorsal tergum, ventral sternum, various parts of the exoskeleton may be fused together. The abdomen bears pleopods, and ends in a telson, which bears the anus, the number and variety of appendages in different crustaceans may be partly responsible for the groups success. It is unclear whether the condition is a derived state which evolved in crustaceans. Trilobites, for instance, also possessed biramous appendages, the main body cavity is an open circulatory system, where blood is pumped into the haemocoel by a heart located near the dorsum. Malacostraca have haemocyanin as the pigment, while copepods, ostracods, barnacles. The alimentary canal consists of a tube that often has a gizzard-like gastric mill for grinding food and a pair of digestive glands that absorb food. Structures that function as kidneys are located near the antennae, a brain exists in the form of ganglia close to the antennae, and a collection of major ganglia is found below the gut. In many decapods, the first pair of pleopods are specialised in the male for sperm transfer, many terrestrial crustaceans mate seasonally and return to the sea to release the eggs. Others, such as woodlice, lay their eggs on land, in most decapods, the females retain the eggs until they hatch into free-swimming larvae. Marine crustaceans are as ubiquitous in the oceans as insects are on land, some branchiurans are able to withstand rapid changes of salinity and will also switch hosts from marine to non-marine species. Krill are the layer and the most important part of the food chain in Antarctic animal communities
11.
Respiratory system
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The respiratory system is a biological system consisting of specific organs and structures used for the process of respiration in an organism. The respiratory system is involved in the intake and exchange of oxygen, in air-breathing vertebrates like human beings, respiration takes place in the respiratory organs called lungs. In humans and other mammals, the features of the respiratory system include trachea, bronchi, bronchioles, lungs. Molecules of oxygen and carbon dioxide are exchanged, by diffusion. This exchange process occurs in the alveoli in the lungs, in fish and many invertebrates, respiration takes place through the gills. Other animals, such as insects, have respiratory systems with very simple anatomical features, 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 features such as holes on the undersides of leaves known as stomata. The elephant is the animal known to have no pleural space. Rather, the parietal and visceral pleura are both composed of connective tissue and joined to each other via loose connective tissue. The respiratory system of birds differs significantly from that found in mammals, 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, 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, both the lungs and the skin serve as respiratory organs in amphibians. The ventilation of the lungs in amphibians uses positive pressure ventilation, muscles lower the floor of the oral cavity, enlarging it and drawing in air through the nostrils. While the lungs are of importance to breathing control, the skins unique properties aid rapid gas exchange when amphibians are submerged in oxygen-rich water. In most fish, respiration takes place through gills, lungfish, however, do possess one or two lungs. The labyrinth fish have developed an organ that allows them to take advantage of the oxygen of the air. Some species of crab use an organ called a branchiostegal lung
12.
Cloaca
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In animal anatomy, a cloaca /kloʊˈeɪkə/ kloh-AY-kə is the posterior orifice that serves as the only opening for the digestive, reproductive, and urinary tracts of certain animals, opening at the vent. Excretory systems with analogous purpose in certain invertebrates are sometimes referred to as cloacae. The cloacal region is often associated with a secretory organ, the cloacal gland, which has been implicated in the scent-marking behavior of some reptiles, amphibians. The word comes from Latin, and means sewer, derived from cluō, birds reproduce using their cloaca, this occurs during a cloacal kiss in most birds. Birds that mate using this method touch their cloacae together, in species for only a few seconds. The reproductive system must be re-engorged before the season of each species. Such regeneration usually takes about a month, birds generally produce one batch of eggs per year, but they will produce another if the first is taken away. For some birds, such as ostriches, cassowaries, kiwi, geese, and some species of swans and ducks, the males do not use the cloaca for reproduction, in those, the penis helps ensure water does not wash away the males sperm during copulation. One study has looked into birds that use their cloaca for cooling, among fish, a true cloaca is present only in elasmobranchs and lobe-finned fishes. In lampreys and in some ray-finned fishes, part of the remains in the adult to receive the urinary and reproductive ducts. In chimaeras and most teleosts, however, all three openings are entirely separated, with a few exceptions noted below, mammals have no cloacae. Even in those that have one, the cloaca is partially subdivided into regions for the anus. The monotremes possess a true cloaca, in marsupials, the genital tract is separate from the anus, but a trace of the original cloaca does remain externally. Unlike other marsupials, marsupial moles have a cloaca, a fact that has been argued against a marsupial identity for these mammals. Most adult placental mammals have no remaining trace of the cloaca, however, the tenrecs and golden moles, small placental mammals native to Africa, as well as some shrews retain a cloaca as adults. Being placental animals, humans only have a cloaca, which is split up into separate tracts during the development of the urinary. However, a few human congenital disorders result in persons being born with a cloaca, including persistent cloaca, some species have modified cloacae for increased gas exchange. This is where reproductive activity occurs, some turtles, especially those specialized in diving, are highly reliant on cloacal respiration during dives
