Caterpillars are the larval stage of members of the order Lepidoptera. As with most common names, the application of the word is arbitrary and the larvae of sawflies are called caterpillars as well. Both lepidopteran and symphytan larvae have eruciform body shapes. Caterpillars of most species are herbivorous, but not all; some feed on other animal products. Caterpillars are voracious feeders and many of them are among the most serious of agricultural pests. In fact many moth species are best known in their caterpillar stages because of the damage they cause to fruits and other agricultural produce, whereas the moths are obscure and do no direct harm. Conversely, various species of caterpillar are valued as sources of silk, as human or animal food, or for biological control of pest plants; the origins of the word "caterpillar" date from the early 16th century. They derive from Middle English catirpel, catirpeller an alteration of Old North French catepelose: cate, cat + pelose, hairy; the inchworm, or looper caterpillars from the family Geometridae are so named because of the way they move, appearing to measure the earth.
Caterpillars have soft bodies that can grow between moults. Their size varies between instars from as small as 1 mm up to 14 cm; some larvae of the order Hymenoptera can appear like the caterpillars of the Lepidoptera. Such larvae are seen in the sawfly suborder; however while these larvae superficially resemble caterpillars, they can be distinguished by the presence of prolegs on every abdominal segment, an absence of crochets or hooks on the prolegs, one pair of prominent ocelli on the head capsule, an absence of the upside-down Y-shaped suture on the front of the head. Lepidopteran caterpillars can be differentiated from sawfly larvae by: the numbers of pairs of pro-legs; the number of stemmata. The presence of crochets on the prolegs. Sawfly larvae have an invariably smooth head capsule with no cleavage lines, while lepidopterous caterpillars bear an inverted "Y" or "V". Many animals feed on caterpillars; as a result, caterpillars have evolved various means of defense. Caterpillars have evolved defenses against physical conditions such as cold, hot or dry environmental conditions.
Some Arctic species like Gynaephora groenlandica have special basking and aggregation behaviours apart from physiological adaptations to remain in a dormant state. The appearance of a caterpillar can repel a predator: its markings and certain body parts can make it seem poisonous, or bigger in size and thus threatening, or non-edible; some types of caterpillars are indeed poisonous or distasteful and their bright coloring is aposematic. Others may mimic other animals while not being dangerous themselves. Many caterpillars are cryptically resemble the plants on which they feed. An example of caterpillars that use camouflage for defence is the species Nemoria arizonaria. If the caterpillars hatch in the spring and feed on oak catkins they appear green. If they hatch in the summer they appear dark colored, like oak twigs; the differential development is linked to the tannin content in the diet. Caterpillars may have spines or growths that resemble plant parts such as thorns; some look like objects in the environment such as bird droppings.
More aggressive self-defense measures are taken by some caterpillars. These measures include having spiny bristles or long fine hair-like setae with detachable tips that will irritate by lodging in the skin or mucous membranes; however some birds will swallow the hairiest of caterpillars. Other caterpillars acquire toxins from their host plants that render them unpalatable to most of their predators. For instance, ornate moth caterpillars utilize pyrrolizidine alkaloids that they obtain from their food plants to deter predators; the most aggressive caterpillar defenses are bristles associated with venom glands. These bristles are called urticating hairs. A venom, among the most potent defensive chemicals in any animal is produced by the South American silk moth genus Lonomia, its venom is an anticoagulant powerful enough to cause a human to hemorrhage to death. This chemical is being investigated for potential medical applications. Most urticating hairs range in effect from mild irritation to dermatitis.
Example: Brown-tail moth. Plants contain toxins which protect them from herbivores, but some caterpillars have evolved countermeasures which enable them to eat the leaves of such toxic plants. In addition to being unaffected by the poison, the caterpillars sequester it in their body, making them toxic to predators; the chemicals are carried on into the adult stages. These toxic species, such as the cinnabar moth and monarch caterpillars advertise themselves with the danger colors of red and black in bright stripes. Any predator that attempts to eat a caterpillar with an aggressive defense mechanism will learn and avoid future attempts; some caterpill
Wikispecies is a wiki-based online project supported by the Wikimedia Foundation. Its aim is to create a comprehensive free content catalogue of all species. Jimmy Wales stated that editors are not required to fax in their degrees, but that submissions will have to pass muster with a technical audience. Wikispecies is available under the GNU Free Documentation License and CC BY-SA 3.0. Started in September 2004, with biologists across the world invited to contribute, the project had grown a framework encompassing the Linnaean taxonomy with links to Wikipedia articles on individual species by April 2005. Benedikt Mandl co-ordinated the efforts of several people who are interested in getting involved with the project and contacted potential supporters in early summer 2004. Databases were evaluated and the administrators contacted, some of them have agreed on providing their data for Wikispecies. Mandl defined two major tasks: Figure out how the contents of the data base would need to be presented—by asking experts, potential non-professional users and comparing that with existing databases Figure out how to do the software, which hardware is required and how to cover the costs—by asking experts, looking for fellow volunteers and potential sponsorsAdvantages and disadvantages were discussed by the wikimedia-I mailing list.
The board of directors of the Wikimedia Foundation voted by 4 to 0 in favor of the establishment of a Wikispecies. The project is hosted at species.wikimedia.org. It was merged to a sister project of Wikimedia Foundation on September 14, 2004. On October 10, 2006, the project exceeded 75,000 articles. On May 20, 2007, the project exceeded 100,000 articles with a total of 5,495 registered users. On September 8, 2008, the project exceeded 150,000 articles with a total of 9,224 registered users. On October 23, 2011, the project reached 300,000 articles. On June 16, 2014, the project reached 400,000 articles. On January 7, 2017, the project reached 500,000 articles. On October 30, 2018, the project reached 600,000 articles, a total of 1.12 million pages. Wikispecies comprises taxon pages, additionally pages about synonyms, taxon authorities, taxonomical publications, institutions or repositories holding type specimen. Wikispecies asks users to use images from Wikimedia Commons. Wikispecies does not allow the use of content.
All Species Foundation Catalogue of Life Encyclopedia of Life Tree of Life Web Project List of online encyclopedias The Plant List Wikispecies, The free species directory that anyone can edit Species Community Portal The Wikispecies Charter, written by Wales
Panama the Republic of Panama, is a country in Central America, bordered by Costa Rica to the west, Colombia to the southeast, the Caribbean Sea to the north, the Pacific Ocean to the south. The capital and largest city is Panama City, whose metropolitan area is home to nearly half the country's 4 million people. Panama was inhabited by indigenous tribes before Spanish colonists arrived in the 16th century, it broke away from Spain in 1821 and joined the Republic of Gran Colombia, a union of Nueva Granada and Venezuela. After Gran Colombia dissolved in 1831, Panama and Nueva Granada became the Republic of Colombia. With the backing of the United States, Panama seceded from Colombia in 1903, allowing the construction of the Panama Canal to be completed by the US Army Corps of Engineers between 1904 and 1914; the 1977 Torrijos–Carter Treaties led to the transfer of the Canal from the United States to Panama on December 31, 1999. Revenue from canal tolls continues to represent a significant portion of Panama's GDP, although commerce and tourism are major and growing sectors.
It is regarded as a high-income country. In 2015 Panama ranked 60th in the world in terms of the Human Development Index. In 2018, Panama was ranked seventh-most competitive economy in Latin America, according to the World Economic Forum's Global Competitiveness Index. Covering around 40 percent of its land area, Panama's jungles are home to an abundance of tropical plants and animals – some of them found nowhere else on the planet. Panama is a founding member of the United Nations and other international organizations such as OAS, LAIA, G77, WHO and NAM; the definite origin of the name Panama is unknown. There are several theories. One postulates that the country was named after a found species of tree. Another that the first settlers arrived in Panama in August, when butterflies abound, that the name means "many butterflies" in one or several of indigenous Amerindian languages that were spoken in the territory prior to Spanish colonization. Most scientifically corroborated theory, that by Panamanian linguists, states that the word is a hispanicization of Kuna language word "bannaba" which means "distant" or "far away".
A relayed legend in Panama is that there was a fishing village that bore the name "Panamá", which purportedly meant "an abundance of fish", when the Spanish colonizers first landed in the area. The exact location of the village is unspecified; the legend is corroborated by Captain Antonio Tello de Guzmán's diary entries, who reports landing at an unnamed village while exploring the Pacific coast of Panama in 1515. In 1517, Don Gaspar de Espinosa, a Spanish lieutenant, decided to settle a post in the same location Guzmán described. In 1519, Pedrarias Dávila decided to establish the Spanish Empire's Pacific port at the site; the new settlement replaced Santa María La Antigua del Darién, which had lost its function within the Crown's global plan after the Spanish exploitation of the riches in the Pacific began. The official definition and origin of the name as promoted by Panama's Ministry of Education is the "abundance of fish and butterflies"; this is the usual description given in social studies textbooks.
At the time of the arrival of the Spanish in the 16th century, the known inhabitants of Panama included the Cuevas and the Coclé tribes. These people have nearly disappeared; the Isthmus of Panama was formed about three million years ago when the land bridge between North and South America became complete, plants and animals crossed it in both directions. The existence of the isthmus affected the dispersal of people and technology throughout the American continent from the appearance of the first hunters and collectors to the era of villages and cities; the earliest discovered artifacts of indigenous peoples in Panama include Paleo-Indian projectile points. Central Panama was home to some of the first pottery-making in the Americas, for example the cultures at Monagrillo, which date back to 2500–1700 BC; these evolved into significant populations best known through their spectacular burials at the Monagrillo archaeological site, their beautiful Gran Coclé style polychrome pottery. The monumental monolithic sculptures at the Barriles site are important traces of these ancient isthmian cultures.
Before Europeans arrived Panama was settled by Chibchan and Cueva peoples. The largest group were the Cueva; the size of the indigenous population of the isthmus at the time of European colonization is uncertain. Estimates range as high as two million people, but more recent studies place that number closer to 200,000. Archaeological finds and testimonials by early European explorers describe diverse native isthmian groups exhibiting cultural variety and suggesting people developed by regular regional routes of commerce; when Panama was colonized, the indigenous peoples fled into nearby islands. Scholars believe that infectious disease was the primary cause of the population decline of American natives; the indigenous peoples had no acquired immunity to diseases, chronic in Eurasian populations for centuries. Rodrigo de Bastidas sailed westward from Venezuela in 1501 in search of gold, became the first European to explore the isthmus of Panama. A year Christopher Columbus visited the isthmus, established a short-lived settlement in the Darien.
Vasco Núñez de Balboa's tortuous
Birds known as Aves, are a group of endothermic vertebrates, characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, a strong yet lightweight skeleton. Birds range in size from the 5 cm bee hummingbird to the 2.75 m ostrich. They rank as the world's most numerically-successful class of tetrapods, with ten thousand living species, more than half of these being passerines, sometimes known as perching birds. Birds have wings which are less developed depending on the species. Wings, which evolved from forelimbs, gave birds the ability to fly, although further evolution has led to the loss of flight in flightless birds, including ratites and diverse endemic island species of birds; the digestive and respiratory systems of birds are uniquely adapted for flight. Some bird species of aquatic environments seabirds and some waterbirds, have further evolved for swimming; the fossil record demonstrates that birds are modern feathered dinosaurs, having evolved from earlier feathered dinosaurs within the theropod group, which are traditionally placed within the saurischian dinosaurs.
The closest living relatives of birds are the crocodilians. Primitive bird-like dinosaurs that lie outside class Aves proper, in the broader group Avialae, have been found dating back to the mid-Jurassic period, around 170 million years ago. Many of these early "stem-birds", such as Archaeopteryx, were not yet capable of powered flight, many retained primitive characteristics like toothy jaws in place of beaks, long bony tails. DNA-based evidence finds that birds diversified around the time of the Cretaceous–Palaeogene extinction event 66 million years ago, which killed off the pterosaurs and all the non-avian dinosaur lineages, but birds those in the southern continents, survived this event and migrated to other parts of the world while diversifying during periods of global cooling. This makes them the sole surviving dinosaurs according to cladistics; some birds corvids and parrots, are among the most intelligent animals. Many species annually migrate great distances. Birds are social, communicating with visual signals and bird songs, participating in such social behaviours as cooperative breeding and hunting and mobbing of predators.
The vast majority of bird species are monogamous for one breeding season at a time, sometimes for years, but for life. Other species have breeding systems that are polygynous or polyandrous. Birds produce offspring by laying eggs, they are laid in a nest and incubated by the parents. Most birds have an extended period of parental care after hatching; some birds, such as hens, lay eggs when not fertilised, though unfertilised eggs do not produce offspring. Many species of birds are economically important as food for human consumption and raw material in manufacturing, with domesticated and undomesticated birds being important sources of eggs and feathers. Songbirds and other species are popular as pets. Guano is harvested for use as a fertiliser. Birds prominently figure throughout human culture. About 120–130 species have become extinct due to human activity since the 17th century, hundreds more before then. Human activity threatens about 1,200 bird species with extinction, though efforts are underway to protect them.
Recreational birdwatching is an important part of the ecotourism industry. The first classification of birds was developed by Francis Willughby and John Ray in their 1676 volume Ornithologiae. Carl Linnaeus modified that work in 1758 to devise the taxonomic classification system in use. Birds are categorised as the biological class Aves in Linnaean taxonomy. Phylogenetic taxonomy places Aves in the dinosaur clade Theropoda. Aves and a sister group, the clade Crocodilia, contain the only living representatives of the reptile clade Archosauria. During the late 1990s, Aves was most defined phylogenetically as all descendants of the most recent common ancestor of modern birds and Archaeopteryx lithographica. However, an earlier definition proposed by Jacques Gauthier gained wide currency in the 21st century, is used by many scientists including adherents of the Phylocode system. Gauthier defined Aves to include only the crown group of the set of modern birds; this was done by excluding most groups known only from fossils, assigning them, instead, to the Avialae, in part to avoid the uncertainties about the placement of Archaeopteryx in relation to animals traditionally thought of as theropod dinosaurs.
Gauthier identified four different definitions for the same biological name "Aves", a problem. Gauthier proposed to reserve the term Aves only for the crown group consisting of the last common ancestor of all living birds and all of its descendants, which corresponds to meaning number 4 below, he assigned other names to the other groups. Aves can mean all archosaurs closer to birds than to crocodiles Aves can mean those advanced archosaurs with feathers Aves can mean those feathered dinosaurs that fly Aves can mean the last common ancestor of all the living birds and all of its descendants (a "c
Mud-puddling, or puddling, is a behaviour most conspicuous in butterflies, but occurs in other animals as well insects. Where the conditions are suitable, conspicuous insects such as butterflies form aggregations on wet soil, dung or carrion. From the fluids they obtain salts and amino acids that play various roles in their physiology and ecology; this behaviour has been seen in some other insects, notably the leafhoppers, e.g. the potato leafhopper, Empoasca fabae. Lepidoptera are diverse in their strategies to gather liquid nutrients. Mud-puddling behaviour takes place on wet soil, but sweat on human skin may be attractive to butterflies such as species of Halpe. More unusual sources include blood and tears. Again, similar behaviour is not limited to the Lepidoptera, for example, the various species of bees called sweat bees are attracted to various kinds of sweat and tears, including that of humans, other bee species have been recorded as doing so to various degrees. In many species puddling behaviour is more seen in males.
Furthermore, the presence of an assembly of butterflies on the ground acts on Battus philenor for example, as a stimulus to join the presumptive mud-puddling flock. In tropical India this phenomenon is seen in the post-monsoon season; the groups include several species members of the families Papilionidae and Pieridae. Males seem to benefit from the sodium uptake through mud-puddling behaviour with an increase in reproductive success; the collected sodium and amino acids are transferred to the female with the spermatophore during mating as a nuptial gift. This nutrition enhances the survival rate of the eggs; when puddling, many butterflies and moths pump fluid through the digestive tract and release fluid from their anus. In some, such as the male notodontid Gluphisia crenata, this is released in forced anal jets at 3 second intervals. Fluid of up to 600 times the body mass may pass through and males have a much longer ileum than non-puddling females; some Orthoptera – e.g. the yellow-spined bamboo locust – are attracted to human urine to the sodium and ammonium ions in it.
Those Lepidoptera that are attracted to dung or carrion seem to prefer ammonium ions rather than sodium. In rotting, the tissues of fruits release sugars and other organic compounds such as alcohols that result from the metabolic processes of decay organisms, used as fuel by butterflies. In Borneo lowland rain forest, numerous species of butterflies visit decaying fruit to drink; this behavior is opportunistic, though some are attracted to old fruit, notably Satyrinae and Limenitidinae such as Bassarona dunya. Carrion is more intentionally utilized. Carrion-feeders seem to represent a different feeding guild from "classical" mud-puddlers and fruit-feeders, they include diverse taxa, e.g. brush-footed butterflies such as Cirrochroa emalea of the Nymphalinae or the tawny rajah of the Charaxinae, as well as gossamer-winged butterflies like Curetis tagalica of the Curetinae or the common imperial of the Theclinae. Carrion-feeding has evolved independently in several lineages. Specialist carrion-feeders may have the ability to smell out and home in on rotting meat over hundreds of meters.
In the Bornean Charaxinae, specialist or opportunistic tend to have a markedly larger bulk and smaller wings, making them more dashing, maneuvrable flyers than fruit specialists like Prothoe franck and opportunistic fruit visitors such as Charaxes durnfordi. Other butterflies like most Pieridae and Morphinae are if seen on carrion and rotting fruit, though they may be avid mud-puddlers in the strict sense. Altogether, the Nymphalidae show the highest variety of nutrient-gathering strategies among the butterflies. Certain moths of the subfamily Calpinae, are somewhat notorious for their blood- and tear-drinking habits. Hemiceratoides hieroglyphica of Madagascar has been noted to visit and suck tears by inserting their proboscis into the closed eyelids of roosting birds. Similar behaviour has been reported in Azeta melanea in Gorgone macarea in Brazil. Other cases of moths drinking human tears have been reported from Thailand; some species of the genus Calyptra are called "vampire moths" as they suck blood from sleeping vertebrates, including humans.
Ophthalmotropy and lachryphagy occur in a number of unrelated moths. Mecistoptera griseifusa is a notable example; as shown in the above photo, Dryas iulia has been observed agitating the eyes of caimans and turtles in order to force tear production, which the male butterflies of the species can drink for minerals. The minerals, which can be obtained from more typical mud-puddling behavior, are used for the butterfly's spermatophores during sexual reproduction
Binomial nomenclature called binominal nomenclature or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages. Such a name is called a binomen, binominal name or a scientific name; the first part of the name – the generic name – identifies the genus to which the species belongs, while the second part – the specific name or specific epithet – identifies the species within the genus. For example, humans belong within this genus to the species Homo sapiens. Tyrannosaurus rex is the most known binomial; the formal introduction of this system of naming species is credited to Carl Linnaeus beginning with his work Species Plantarum in 1753. But Gaspard Bauhin, in as early as 1623, had introduced in his book Pinax theatri botanici many names of genera that were adopted by Linnaeus; the application of binomial nomenclature is now governed by various internationally agreed codes of rules, of which the two most important are the International Code of Zoological Nomenclature for animals and the International Code of Nomenclature for algae and plants.
Although the general principles underlying binomial nomenclature are common to these two codes, there are some differences, both in the terminology they use and in their precise rules. In modern usage, the first letter of the first part of the name, the genus, is always capitalized in writing, while that of the second part is not when derived from a proper noun such as the name of a person or place. Both parts are italicized when a binomial name occurs in normal text, thus the binomial name of the annual phlox is now written as Phlox drummondii. In scientific works, the authority for a binomial name is given, at least when it is first mentioned, the date of publication may be specified. In zoology "Patella vulgata Linnaeus, 1758"; the name "Linnaeus" tells the reader who it was that first published a description and name for this species of limpet. "Passer domesticus". The original name given by Linnaeus was Fringilla domestica; the ICZN does not require that the name of the person who changed the genus be given, nor the date on which the change was made, although nomenclatorial catalogs include such information.
In botany "Amaranthus retroflexus L." – "L." is the standard abbreviation used in botany for "Linnaeus". "Hyacinthoides italica Rothm. – Linnaeus first named this bluebell species Scilla italica. The name is composed of two word-forming elements: "bi", a Latin prefix for two, "-nomial", relating to a term or terms; the word "binomium" was used in Medieval Latin to mean a two-term expression in mathematics. Prior to the adoption of the modern binomial system of naming species, a scientific name consisted of a generic name combined with a specific name, from one to several words long. Together they formed a system of polynomial nomenclature; these names had two separate functions. First, to designate or label the species, second, to be a diagnosis or description. In a simple genus, containing only two species, it was easy to tell them apart with a one-word genus and a one-word specific name; such "polynomial names" may sometimes look like binomials, but are different. For example, Gerard's herbal describes various kinds of spiderwort: "The first is called Phalangium ramosum, Branched Spiderwort.
The other... is aptly termed Phalangium Ephemerum Virginianum, Soon-Fading Spiderwort of Virginia". The Latin phrases are short descriptions, rather than identifying labels; the Bauhins, in particular Caspar Bauhin, took some important steps towards the binomial system, by pruning the Latin descriptions, in many cases to two words. The adoption by biologists of a system of binomial nomenclature is due to Swedish botanist and physician Carl von Linné, more known by his Latinized name Carl Linnaeus, it was in his 1753 Species Plantarum that he first began using a one-word "trivial name" together with a generic name in a system of binomial nomenclature. This trivial name is what is now known as specific name; the Bauhins' genus names were retained in many of these, but the descriptive part was reduced to a single word. Linnaeus's trivial names introduced an important new idea, namely that the function of a name could be to give a species a unique label; this meant. Thus Gerard's Phalangium ephemerum virginianum became Tradescantia virgi
Animals are multicellular eukaryotic organisms that form the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, grow from a hollow sphere of cells, the blastula, during embryonic development. Over 1.5 million living animal species have been described—of which around 1 million are insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from 8.5 millionths of a metre to 33.6 metres and have complex interactions with each other and their environments, forming intricate food webs. The category includes humans, but in colloquial use the term animal refers only to non-human animals; the study of non-human animals is known as zoology. Most living animal species are in the Bilateria, a clade whose members have a bilaterally symmetric body plan; the Bilateria include the protostomes—in which many groups of invertebrates are found, such as nematodes and molluscs—and the deuterostomes, containing the echinoderms and chordates.
Life forms interpreted. Many modern animal phyla became established in the fossil record as marine species during the Cambrian explosion which began around 542 million years ago. 6,331 groups of genes common to all living animals have been identified. Aristotle divided animals into those with those without. Carl Linnaeus created the first hierarchical biological classification for animals in 1758 with his Systema Naturae, which Jean-Baptiste Lamarck expanded into 14 phyla by 1809. In 1874, Ernst Haeckel divided the animal kingdom into the multicellular Metazoa and the Protozoa, single-celled organisms no longer considered animals. In modern times, the biological classification of animals relies on advanced techniques, such as molecular phylogenetics, which are effective at demonstrating the evolutionary relationships between animal taxa. Humans make use of many other animal species for food, including meat and eggs. Dogs have been used in hunting, while many aquatic animals are hunted for sport.
Non-human animals have appeared in art from the earliest times and are featured in mythology and religion. The word "animal" comes from the Latin animalis, having soul or living being; the biological definition includes all members of the kingdom Animalia. In colloquial usage, as a consequence of anthropocentrism, the term animal is sometimes used nonscientifically to refer only to non-human animals. Animals have several characteristics. Animals are eukaryotic and multicellular, unlike bacteria, which are prokaryotic, unlike protists, which are eukaryotic but unicellular. Unlike plants and algae, which produce their own nutrients animals are heterotrophic, feeding on organic material and digesting it internally. With few exceptions, animals breathe oxygen and respire aerobically. All animals are motile during at least part of their life cycle, but some animals, such as sponges, corals and barnacles become sessile; the blastula is a stage in embryonic development, unique to most animals, allowing cells to be differentiated into specialised tissues and organs.
All animals are composed of cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins. During development, the animal extracellular matrix forms a flexible framework upon which cells can move about and be reorganised, making the formation of complex structures possible; this may be calcified, forming structures such as shells and spicules. In contrast, the cells of other multicellular organisms are held in place by cell walls, so develop by progressive growth. Animal cells uniquely possess the cell junctions called tight junctions, gap junctions, desmosomes. With few exceptions—in particular, the sponges and placozoans—animal bodies are differentiated into tissues; these include muscles, which enable locomotion, nerve tissues, which transmit signals and coordinate the body. There is an internal digestive chamber with either one opening or two openings. Nearly all animals make use of some form of sexual reproduction, they produce haploid gametes by meiosis.
These fuse to form zygotes, which develop via mitosis into a hollow sphere, called a blastula. In sponges, blastula larvae swim to a new location, attach to the seabed, develop into a new sponge. In most other groups, the blastula undergoes more complicated rearrangement, it first invaginates to form a gastrula with a digestive chamber and two separate germ layers, an external ectoderm and an internal endoderm. In most cases, a third germ layer, the mesoderm develops between them; these germ layers differentiate to form tissues and organs. Repeated instances of mating with a close relative during sexual reproduction leads to inbreeding depression within a population due to the increased prevalence of harmful recessive traits. Animals have evolved numerous mechanisms for avoiding close inbreeding. In some species, such as the splendid fairywren, females benefit by mating with multiple males, thus producing more offspring of higher genetic quality; some animals are capable of asexual reproduction, which results