1.
Papilio xuthus
–
It was also recorded in the state of Arunachal Pradesh, India, in 2014. It mates multiple times in its life, leading to a genetic diversity in its young. It is preyed upon by a host of organisms, including the tree cricket Oecanthus longicauda, ant Lasius niger, P. xuthus utilizes color vision and color constancy while foraging for plants of the family Rutaceae. It is common and not threatened, Papilio xuthus is common in urban, suburban, woods and orange orchards. The flight period is from May to August, males use both physical and visual cues to attract mates during the breeding season. Females of the species regularly mate with multiple partners, after mating, females use habitat and food quality to determine where they will oviposit their eggs. Papilio xuthus is a member of the Papilio genus, of which Papilio appalachiensis, Papilio canadensis and it is of the family Papilionidae and order Lepidoptera. It was first introduced in Hawaii in 1971 from Japan or Guam, P. xuthus makes significant seasonal migrations over 200 km. There are two subspecies of P. xuthus, Papilio xuthus koxingus and Papilio xuthus neoxuthus, the Asian swallowtail is a mid-sized, yellow, prominently-tailed butterfly. It has a wingspan of 45 to 55 mm and its normal color pattern consists of a black pattern on a yellow background. Wing coloration is sexually dimorphic, with females showing broader proximal marginal bands in the hindwing, blue-iridesecent and orange scales separate the black bands on the hindwing. The black bands also run in stripes of varying thickness along the forewing, the young caterpillar mimics bird feces and has a white and brown spot on its head. As they mature, caterpillars develop a green body color with brown spots. During the mating season, Asian swallowtail males fly through the foliage of trees in search of a mate. If a male encounters a female resting on a plant with open and horizontal wings, it approaches her, in addition, males use visual cues to conduct the mating ritual and are particularly attracted to closely spaced yellow patches on female wings. Most females of the Asian swallowtail butterfly mate more than once in their life and this behavior is typical of many other swallowtail butterflies including P. glaucus, P. helenus and P. protenor. By mating multiply, females are able to increase the diversity of their offspring. In addition, multiple matings allow females to produce a number of eggs
2.
Butterfly
–
Butterflies are insects in the macrolepidopteran clade Rhopalocera from the order Lepidoptera, which also includes moths. Adult butterflies have large, often brightly coloured wings, and conspicuous, the group comprises the large superfamily Papilionoidea, which contains at least one former group, the skippers and the most recent analyses suggest it also contains the moth-butterflies. Butterfly fossils date to the Paleocene, which was about 56 million years ago, Butterflies have the typical four-stage insect life cycle. Winged adults lay eggs on the plant on which their larvae, known as caterpillars. The caterpillars grow, sometimes rapidly, and when fully developed. When metamorphosis is complete, the skin splits, the adult insect climbs out. Butterflies are often polymorphic, and many species use of camouflage, mimicry. Some, like the monarch and the lady, migrate over long distances. Many butterflies are attacked by parasites or parasitoids, including wasps, protozoans, flies, some species are pests because in their larval stages they can damage domestic crops or trees, other species are agents of pollination of some plants. Larvae of a few butterflies eat harmful insects, and a few are predators of ants, culturally, butterflies are a popular motif in the visual and literary arts. The Oxford English Dictionary derives the word straightforwardly from Old English butorflēoge, butter-fly, similar names in Old Dutch, the earliest Lepidoptera fossils are of a small moth, Archaeolepis mane, of Jurassic age, around 190 million years ago. Butterflies evolved from moths, so while the butterflies are monophyletic, the oldest butterflies are from the Palaeocene MoClay or Fur Formation of Denmark. The oldest American butterfly is the Late Eocene Prodryas persephone from the Florissant Fossil Beds, traditionally, the butterflies have been divided into the superfamily Papilionoidea excluding the smaller groups of the Hesperiidae and the more moth-like Hedylidae of America. Butterfly adults are characterized by their four scale-covered wings, which give the Lepidoptera their name, as in all insects, the body is divided into three sections, the head, thorax, and abdomen. The thorax is composed of three segments, each with a pair of legs, in most families of butterfly the antennae are clubbed, unlike those of moths which may be threadlike or feathery. The long proboscis can be coiled when not in use for sipping nectar from flowers, some day-flying moths, such as the hummingbird hawk-moth, are exceptions to these rules. Butterfly larvae, caterpillars, have a head with strong mandibles used for cutting their food. They have cylindrical bodies, with ten segments to the abdomen, generally with short prolegs on segments 3–6 and 10, many are well camouflaged, others are aposematic with bright colours and bristly projections containing toxic chemicals obtained from their food plants
3.
Animal
–
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
4.
Metamorphosis
–
Metamorphosis is iodothyronine-induced and an ancestral feature of all chordates. Some insects, fishes, amphibians, mollusks, crustaceans, cnidarians, echinoderms, and tunicates undergo metamorphosis, animals that go through metamorphosis are called metamorphoses. Animals can be divided into species that undergo metamorphosis, incomplete metamorphosis. Scientific usage of the term is technically precise, and it is not applied to general aspects of cell growth, the word metamorphosis derives from Greek μεταμόρφωσις, transformation, transforming, from μετα-, change and μορφή, form. Metamorphosis is iodothyronine-induced and a feature of all chordates. In insects growth and metamorphosis are controlled by hormones synthesized by endocrine glands near the front of the body, neurosecretory cells in an insects brain secrete a hormone, the prothoracicotropic hormone that activates prothoracic glands, which secrete a second hormone, usually ecdysone, that induces ecdysis. PTTH also stimulates the corpora allata, an organ, to produce juvenile hormone. Experiments on firebugs have shown how juvenile hormone can affect the number of nymph instar stages in hemimetabolous insects, All three categories can be found in the diversity of insects, including no metamorphosis, incomplete or partial metamorphosis, and complete metamorphosis. In hemimetabolous insects, immature stages are called nymphs, development proceeds in repeated stages of growth and ecdysis, these stages are called instars. The juvenile forms closely resemble adults, but are smaller and lack features such as wings. The size and morphological differences between nymphs in different instars are small, often just differences in proportions and the number of segments, in later instars. In holometabolous insects, immature stages are called larvae, and differ markedly from adults, insects which undergo holometabolism pass through a larval stage, then enter an inactive state called pupa, and finally emerge as adults. The earliest insect forms showed direct development, and the evolution of metamorphosis in insects is thought to have fuelled their dramatic radiation, some early ametabolous true insects are still present today, such as bristletails and silverfish. Hemimetabolous insects include cockroaches, grasshoppers, dragonflies, and true bugs, phylogenetically, all insects in the Pterygota undergo a marked change in form, texture and physical appearance from immature stage to adult. According to research from 2008, adult Manduca sexta is able to retain behavior learned as a caterpillar, many observations have indicated that programmed cell death plays a considerable role during physiological processes of multicellular organisms, particularly during embryogenesis and metamorphosis. Sequence illustrating complete metamorphosis in the white butterfly, Pieris rapae In typical amphibian development, eggs are laid in water. Frogs, toads, and newts all hatch from the eggs as larvae with external gills, afterwards, newt larvae start a predatory lifestyle, while tadpoles mostly scrape food off surfaces with their horny tooth ridges. Metamorphosis in amphibians is regulated by thyroxin concentration in the blood, which stimulates metamorphosis, and prolactin, specific events are dependent on threshold values for different tissues
5.
Cnidaria
–
Cnidaria is a phylum containing over 9,000 species of animals found exclusively in aquatic environments, they are predominantly marine species. Their distinguishing feature is cnidocytes, specialized cells that use mainly for capturing prey. Their bodies consist of mesoglea, a non-living jelly-like substance, sandwiched between two layers of epithelium that are one cell thick. They have two basic forms, swimming medusae and sessile polyps, both of which are radially symmetrical with mouths surrounded by tentacles that bear cnidocytes. Both forms have a single orifice and body cavity that are used for digestion and respiration, many cnidarian species produce colonies that are single organisms composed of medusa-like or polyp-like zooids, or both. Cnidarians activities are coordinated by a nerve net and simple receptors. Several free-swimming species of Cubozoa and Scyphozoa possess balance-sensing statocysts, not all cnidarians reproduce sexually, with many species having complex life cycles of asexual polyp stages and sexual medusae. Some, however, omit either the polyp or the medusa stage, Cnidarians were formerly grouped with ctenophores in the phylum Coelenterata, but increasing awareness of their differences caused them to be placed in separate phyla. Staurozoa have recently been recognised as a class in their own rather than a sub-group of Scyphozoa. Most cnidarians prey on organisms ranging in size from plankton to animals several times larger than themselves, but many obtain much of their nutrition from dinoflagellates, many are preyed on by other animals including starfish, sea slugs, fish and turtles. Many scleractinian corals—which form the foundation for coral reefs—possess polyps that are filled with zooxanthellae. While reef-forming corals are almost entirely restricted to warm and shallow waters, other cnidarians can be found at great depths, in polar regions. Recent phylogenetic analyses support monophyly of cnidarians, as well as the position of cnidarians as the group of bilaterians. Cnidarians form a phylum that are more complex than sponges, about as complex as ctenophores, and less complex than bilaterians. Cnidarians are distinguished from all other animals by having cnidocytes that fire like harpoons and are used mainly to capture prey, in some species, cnidocytes can also be used as anchors. Hence, cnidarians and ctenophores have traditionally been labelled diploblastic, along with sponges, however, both cnidarians and ctenophores have a type of muscle that, in more complex animals, arises from the middle cell layer. As a result, some recent text books classify ctenophores as triploblastic, adult cnidarians appear as either swimming medusae or sessile polyps, and many hydrozoan species are known to alternate between the two forms. Both are radially symmetrical, like a wheel and a tube respectively, since these animals have no heads, their ends are described as oral and aboral
6.
Caterpillar
–
Caterpillars /ˈkætərˌpɪlər/ are the larval stage of members of the order Lepidoptera. As with most common names, the application of the word is arbitrary, caterpillars of most species are herbivorous, but not all, some are insectivorous, even cannibalistic. Some feed on other products, for example clothes moths feed on wool. Caterpillars as a rule 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 cause to fruits and other agricultural produce, whereas the moths are obscure. Conversely, various species of caterpillar are valued as sources of silk, as human or animal food, the origins of the word caterpillar date from the early 16th century. They derive from Middle English catirpel, catirpeller, probably an alteration of Old North French catepelose, cate, cat + pelose, caterpillars have soft bodies that can grow rapidly between moults. Only the head capsule is hardened, the mandibles are tough and sharp for chewing leaves. Behind the mandibles of the caterpillar are the spinnerets, for manipulating silk, antennae are present on either side of the labrum, but small and relatively inconspicuous. Some larvae of the Hymenoptera order can appear like the caterpillars of the Lepidoptera, such larvae are mainly seen in the sawfly family. Caterpillars can be confused with the larvae of sawflies, lepidopteran larvae can be differentiated by, the numbers of pairs of pro-legs, sawfly larvae have 6 while caterpillars have up to 5 pairs. The number of stemmata, the larvae have only two, while a caterpillar has six. The presence of crochets on the prolegs, these are absent in the Symphyta, 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 they are rich in protein, as a result, caterpillars have evolved various means of defense. The appearance of a caterpillar can often repel a predator, its markings and certain body parts can make it seem poisonous, or bigger in size and thus threatening, some types of caterpillars are indeed poisonous. 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. Many caterpillars are cryptically colored and resemble the plants on which they feed and they may even have parts that mimic plant parts such as thorns. Their size varies from as little as 1 mm to about 75 millimetres, some look like objects in the environment such as bird droppings
7.
Tadpole
–
A tadpole is the larval stage in the life cycle of an amphibian, particularly that of a frog or toad. They are usually wholly aquatic, though some species have tadpoles that are terrestrial, when first hatched from the egg they have a more or less globular body, a laterally compressed tail and internal or external gills. As they grow they undergo metamorphosis, during which process they grow limbs, develop lungs, most tadpoles are herbivorous and during metamorphosis the mouth and internal organs are rearranged to prepare for an adult carnivorous lifestyle. Having no hard parts, it might be expected that fossil tadpoles would not exist, however, traces of biofilms have been preserved and fossil tadpoles have been found dating back to the Miocene. Tadpoles are eaten in parts of the world and are mentioned in folk tales. The name tadpole is from Middle English taddepol, made up of the elements tadde, toad, similarly, pollywog / polliwog is from Middle English polwygle, made up of the same pol, head, and wiglen, to wiggle. Tadpoles are young amphibians that live in the water, though a few tadpoles are semi-terrestrial and terrestrial. During the tadpole stage of the life cycle, most respire by means of autonomous external or internal gills. They do not usually have arms or legs until the transition to adulthood, as a tadpole matures, it most commonly metamorphosizes by gradually growing limbs and then outwardly absorbing its tail by apoptosis. Lungs develop around the time of leg development, and tadpoles late in development will often be found near the surface of the water, where they breathe air. During the final stages of external metamorphosis, the mouth changes from a small. The intestines shorten to accommodate the new diet, most tadpoles are herbivorous, subsisting on algae and plants. Some species are omnivorous, eating detritus and, when available, tadpoles vary greatly in size, both during their development and between species. For example, in a family, Megophryidae, length of late-stage tadpoles varies between 33 millimetres and 106 millimetres. The tadpoles of Pseudis paradoxa grow to 25 centimetres, the largest of any frog, despite their soft-bodied nature and lack of mineralised hard parts, fossil tadpoles have been recovered from Upper Miocene strata. They are preserved by virtue of biofilms, with more robust structures preserved as a carbon film, in Miocene fossils from Libros, Spain, the brain case is preserved in calcium carbonate, and the nerve cord in calcium phosphate. Other parts of the tadpoles bodies exist as organic remains and bacterial biofilms, tadpole remains with telltale external gills are also known from several of the Labyrinthodont groups. Some tadpoles are used as food, tadpoles of megophryid frog Oreolalax rhodostigmatus are particularly large, more than 10 cm in length, and are collected for human consumption in China
8.
Frog
–
A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura. The oldest fossil proto-frog appeared in the early Triassic of Madagascar, Frogs are widely distributed, ranging from the tropics to subarctic regions, but the greatest concentration of species diversity is in tropical rainforests. There are approximately 4,800 recorded species, accounting for over 85% of extant amphibian species and they are also one of the five most diverse vertebrate orders. The body plan of a frog is generally characterized by a stout body, protruding eyes, cleft tongue, limbs folded underneath. Besides living in water and on dry land, the adults of some species are adapted for living underground or in trees. The skin of the frog is glandular, with secretions ranging from distasteful to toxic, Frogs skins vary in colour from well-camouflaged dappled brown, grey and green to vivid patterns of bright red or yellow and black to advertise toxicity and warn off predators. Frogs typically lay their eggs in water, the eggs hatch into aquatic larvae called tadpoles that have tails and internal gills. They have highly specialized rasping mouth parts suitable for herbivorous, omnivorous or planktivorous diets, the life cycle is completed when they metamorphose into adults. A few species deposit eggs on land or bypass the tadpole stage, adult frogs generally have a carnivorous diet consisting of small invertebrates, but omnivorous species exist and a few feed on fruit. Frogs are extremely efficient at converting what they eat into body mass and they are an important food source for predators and part of the food web dynamics of many of the worlds ecosystems. The skin is semi-permeable, making them susceptible to dehydration, so they live in moist places or have special adaptations to deal with dry habitats. Frogs are valued as food by humans and also have many roles in literature, symbolism. Frog populations have declined significantly since the 1950s, more than one third of species are considered to be threatened with extinction and over one hundred and twenty are believed to have become extinct since the 1980s. The number of malformations among frogs is on the rise and a fungal disease. Conservation biologists are working to understand the causes of these problems, the name frog derives from Old English frogga, abbreviated to frox, forsc, and frosc, probably deriving from Proto-Indo-European preu = to jump. About 88% of amphibian species are classified in the order Anura and these include around 4,810 species in 33 families, of which the Leptodactylidae, Hylidae and Ranidae are the richest in species. The use of the common frog and toad has no taxonomic justification. From a classification perspective, all members of the order Anura are frogs, there are numerous exceptions to this rule
9.
Barnacle
–
A barnacle is a type of arthropod constituting the infraclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters and they are sessile suspension feeders, and have two nektonic larval stages. Around 1,220 barnacle species are currently known, the name Cirripedia is Latin, meaning curl-footed. Barnacles are encrusters, attaching themselves permanently to a hard substrate, the most common, acorn barnacles, are sessile, growing their shells directly onto the substrate. The order Pedunculata attach themselves by means of a stalk, free-living barnacles are attached to the substratum by cement glands that form the base of the first pair of antennae, in effect, the animal is fixed upside down by means of its forehead. In some barnacles, the cement glands are fixed to a long, muscular stalk, a ring of plates surrounds the body, homologous with the carapace of other crustaceans. These consist of the rostrum, two plates, two carinolaterals, and a carina. In sessile barnacles, the apex of the ring of plates is covered by an operculum, the plates are held together by various means, depending on species, in some cases being solidly fused. Inside the carapace, the lies on its back, with its limbs projecting upwards. Segmentation is usually indistinct, and the body is more or less divided between the head and thorax, with little, if any, abdomen. Adult barnacles have few appendages on their heads, with only a single, vestigial pair of antennae, attached to the cement gland. The six pairs of limbs are referred to as cirri. Barnacles have no heart, although a sinus close to the esophagus performs similar function. The blood vascular system is minimal, similarly, they have no gills, absorbing oxygen from the water through their limbs and the inner membrane of their carapaces. The excretory organs of barnacles are maxillary glands, the main sense of barnacles appears to be touch, with the hairs on the limbs being especially sensitive. The adult also has an eye, although this is probably only capable of sensing the difference between light and dark. This eye is derived from the naupliar eye. Barnacles have two larval stages, the nauplius and the cyprid, before developing into a mature adult
10.
Hymenoptera
–
Hymenoptera is the third-largest order of insects, comprising the sawflies, wasps, bees, and ants. Over 150,000 species are recognized, with many more remaining to be described, females typically have a special ovipositor for inserting eggs into hosts or otherwise inaccessible places. The ovipositor is modified into a stinger. The young develop through holometabolism —that is, they have a larval stage. The name Hymenoptera refers to the wings of the insects, all references agree that the derivation involves the Ancient Greek πτερόν for wing. The Ancient Greek ὑμήν for membrane provides an etymology for the term because this order like several others has membranous wings. However, a key characteristic of this order is that the wings are connected to the fore wings by a series of hooks. Thus, another plausible etymology involves Hymen, the Ancient Greek god of marriage, Hymenoptera originated in the Triassic, with the oldest fossils belonging to the family Xyelidae. Social hymenopterans appeared during the Cretaceous, the evolution of this group has been intensively studied by Alex Rasnitsyn, Michael S. Engel, G. Dlussky, and others. This clade has been studied by examining the mitochondrial DNA, although this study was unable to resolve all the ambiguities in this clade, some relationships could be established. The Aculeata, Ichneumonomorpha, and Proctotrupomorpha were monophyletic, the Megalyroidea and Trigonalyoidea are sister clades as are the Chalcidoidea+Diaprioidea. The Cynipoidea was generally recovered as the group to Chalcidoidea and Diaprioidea which are each others closest relations. The cladogram is based on Schulmeister 2003, hymenopterans range in size from very small to large insects, and usually have two pairs of wings. Their mouthparts are adapted for chewing, with well-developed mandibles, many species have further developed the mouthparts into a lengthy proboscis, with which they can drink liquids, such as nectar. They have large eyes, and typically three simple eyes. The forward margin of the hind wing bears a number of hooked bristles, or hamuli, the smaller species may have only two or three hamuli on each side, but the largest wasps may have a considerable number, keeping the wings gripped together especially tightly. Hymenopteran wings have relatively few veins compared with other insects. In the more ancestral hymenopterans, the ovipositor is blade-like, and has evolved for slicing plant tissues, in the majority, however, it is modified for piercing, and, in some cases, is several times the length of the body
11.
Newt
–
A newt is a salamander in the subfamily Pleurodelinae, also called eft during its terrestrial juvenile phase. Unlike other members of the family Salamandridae, newts are semiaquatic, not all aquatic salamanders are considered newts, however. The more than 100 known species of newts are found in North America, Europe, North Africa, newts metamorphose through three distinct developmental life stages, aquatic larva, terrestrial juvenile, and adult. Adult newts have lizard-like bodies and return to the every year to breed, otherwise living in humid. Newts are threatened by loss, fragmentation and pollution. Several species are endangered, and at least one species, the Yunnan lake newt, has gone extinct recently, the Old English name of the animal was efte, efeta, resulting in Middle English eft, this word was transformed irregularly into euft, evete, or ewt. The initial n was added from the article an by provection by the early 15th century. The form newt appears to have arisen as a variant of eft in Staffordshire. Dialectal English and Scots also has the word ask used for both newts and wall lizards, from Old English āþexe, from Proto-Germanic *agiþahsijǭ, literally lizard-badger or distaff-like lizard. Latin had the name stellio for a type of spotted newt, ancient Greek had the name κορδύλος, presumably for the water newt. German has Molch, from Middle High German mol, wikt, olm, newts are also known as Tritones in historical literature, and triton remains in use as common name in some Romance languages, in Greek, in Russian and Serbian. The systematic name Tritones was introduced alongside Pleurodelinae by Tschudi in 1838, laurentis Triton was renamed to Triturus by Rafinesque in 1815. Tschudis Pleurodelinae is based on the type genus Pleurodeles named by Michahelles in 1830, newts are found in North America, Europe, North Africa and Asia. Eastern Asia, from Eastern India over Indochina to Japan, is home to five genera with more than 40 species, newts are semi-aquatic, spending part of the year in the water for reproduction and the rest of the year on land. While most species prefer stagnant water bodies such as ponds, ditches or flooded meadows for reproduction, the European brook newts and European mountain newts have even adapted to life in cold, oxygen-rich mountain streams. During their terrestrial phase, newts live in habitats with abundandant cover such as logs, rocks. Newts share many of the characteristics of their kin, Caudata, including semipermeable glandular skin, four equal-sized limbs. The newts skin, however, is not as smooth as that of other salamanders, aquatic larvae have true teeth on both upper and lower jaws, and external gills
12.
Ctenophora
–
Ctenophora is a phylum of invertebrate animals that live in marine waters worldwide. Their most distinctive feature is the ‘combs’ – groups of cilia which they use for swimming – they are the largest animals that swim by means of cilia, adults of various species range from a few millimeters to 1.5 m in size. Like cnidarians, their bodies consist of a mass of jelly, with one layer of cells on the outside, in ctenophores, these layers are two cells deep, while those in cnidarians are only one cell deep. Some authors combined ctenophores and cnidarians in one phylum, Coelenterata, increasing awareness of the differences persuaded more recent authors to classify them as separate phyla. Ctenophores also resemble cnidarians in having a decentralized nerve net rather than a brain, genomic studies have suggested that the neurons of Ctenophora, which differ in many ways from other animal neurons, evolved independently from those of the other animals. In favorable circumstances, ctenophores can eat ten times their own weight in a day, only 100–150 species have been validated, and possibly another 25 have not been fully described and named. The textbook examples are cydippids with egg-shaped bodies and a pair of retractable tentacles fringed with tentilla that are covered with colloblasts, most species are hermaphrodites—a single animal can produce both eggs and sperm, meaning it can fertilize its own egg, not needing a mate. Some are simultaneous hermaphrodites, which can produce eggs and sperm at the same time. Others are sequential hermaphrodites, in which the eggs and sperm mature at different times, fertilization is generally external, although platyctenids eggs are fertilized inside their parents bodies and kept there until they hatch. The young are generally planktonic and in most species look like miniature cydippids, in at least some species, juveniles are capable of reproduction before reaching the adult size and shape. The combination of hermaphroditism and early reproduction enables small populations to grow at an explosive rate, ctenophores may be abundant during the summer months in some coastal locations, but in other places they are uncommon and difficult to find. The situation was aggravated by other factors, such as over-fishing, the later accidental introduction of Beroe helped to mitigate the problem, as Beroe preys on other ctenophores. Ctenophores form a phylum that is more complex than sponges, about as complex as cnidarians. Unlike sponges, both ctenophores and cnidarians have, cells bound by inter-cell connections and carpet-like basement membranes, muscles, nervous systems, ctenophores are distinguished from all other animals by having colloblasts, which are sticky and adhere to prey, although a few ctenophore species lack them. Hence ctenophores and cnidarians have traditionally been labelled diploblastic, along with sponges, ranging from about 1 millimeter to 1.5 meters in size, ctenophores are the largest non-colonial animals that use cilia as their main method of locomotion. The name ctenophora means comb-bearing, from the Greek κτείς meaning comb, for a phylum with relatively few species, ctenophores have a wide range of body plans. Coastal species need to be enough to withstand waves and swirling sediment particles. In addition oceanic species do not preserve well, and are mainly from photographs
Media related to Larva at Wikimedia Commons
The dictionary definition of larva at Wiktionary
