In scientific nomenclature, a synonym is a scientific name that applies to a taxon that goes by a different scientific name, although the term is used somewhat differently in the zoological code of nomenclature. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies; this name is no longer in use: it is now a synonym of the current scientific name, Picea abies. Unlike synonyms in other contexts, in taxonomy a synonym is not interchangeable with the name of which it is a synonym. In taxonomy, synonyms have a different status. For any taxon with a particular circumscription and rank, only one scientific name is considered to be the correct one at any given time. A synonym cannot exist in isolation: it is always an alternative to a different scientific name. Given that the correct name of a taxon depends on the taxonomic viewpoint used a name, one taxonomist's synonym may be another taxonomist's correct name. Synonyms may arise whenever the same taxon is named more than once, independently.
They may arise when existing taxa are changed, as when two taxa are joined to become one, a species is moved to a different genus, a variety is moved to a different species, etc. Synonyms come about when the codes of nomenclature change, so that older names are no longer acceptable. To the general user of scientific names, in fields such as agriculture, ecology, general science, etc. A synonym is a name, used as the correct scientific name but, displaced by another scientific name, now regarded as correct, thus Oxford Dictionaries Online defines the term as "a taxonomic name which has the same application as another one, superseded and is no longer valid." In handbooks and general texts, it is useful to have synonyms mentioned as such after the current scientific name, so as to avoid confusion. For example, if the much advertised name change should go through and the scientific name of the fruit fly were changed to Sophophora melanogaster, it would be helpful if any mention of this name was accompanied by "".
Synonyms used in this way may not always meet the strict definitions of the term "synonym" in the formal rules of nomenclature which govern scientific names. Changes of scientific name have two causes: they may be taxonomic or nomenclatural. A name change may be caused by changes in the circumscription, position or rank of a taxon, representing a change in taxonomic, scientific insight. A name change may be due to purely nomenclatural reasons, that is, based on the rules of nomenclature. Speaking in general, name changes for nomenclatural reasons have become less frequent over time as the rules of nomenclature allow for names to be conserved, so as to promote stability of scientific names. In zoological nomenclature, codified in the International Code of Zoological Nomenclature, synonyms are different scientific names of the same taxonomic rank that pertain to that same taxon. For example, a particular species could, over time, have had two or more species-rank names published for it, while the same is applicable at higher ranks such as genera, orders, etc.
In each case, the earliest published name is called the senior synonym, while the name is the junior synonym. In the case where two names for the same taxon have been published the valid name is selected accorded to the principle of the first reviser such that, for example, of the names Strix scandiaca and Strix noctua, both published by Linnaeus in the same work at the same date for the taxon now determined to be the snowy owl, the epithet scandiaca has been selected as the valid name, with noctua becoming the junior synonym. One basic principle of zoological nomenclature is that the earliest published name, the senior synonym, by default takes precedence in naming rights and therefore, unless other restrictions interfere, must be used for the taxon. However, junior synonyms are still important to document, because if the earliest name cannot be used the next available junior synonym must be used for the taxon. For other purposes, if a researcher is interested in consulting or compiling all known information regarding a taxon, some of this may well have been published under names now regarded as outdated and so it is again useful to know a list of historic synonyms which may have been used for a given current taxon name.
Objective synonyms refer to taxa with same rank. This may be species-group taxa of the same rank with the same type specimen, genus-group taxa of the same rank with the same type species or if their type species are themselves objective synonyms, of family-group taxa with the same type genus, etc. In the case of subjective synonyms, there is no such shared type, so the synonymy is open to taxonomic judgement, meaning that th
Bryozoa are a phylum of aquatic invertebrate animals. About 0.5 millimetres long, they are filter feeders that sieve food particles out of the water using a retractable lophophore, a "crown" of tentacles lined with cilia. Most marine species live in tropical waters, but a few occur in oceanic trenches, others are found in polar waters. One class lives only in a variety of freshwater environments, a few members of a marine class prefer brackish water. Over 4,000 living species are known. One genus is solitary and the rest are colonial; the phylum was called "Polyzoa", but this term was superseded by "Bryozoa" in 1831. Another group of animals discovered subsequently, whose filtering mechanism looked similar, was included in "Bryozoa" until 1869, when the two groups were noted to be different internally; the more discovered group was given the name Entoprocta, while the original "Bryozoa" were called "Ectoprocta". However, "Bryozoa" has remained the more used term for the latter group. Individuals in bryozoan colonies are called zooids, since they are not independent animals.
All colonies contain autozooids, which are responsible for excretion. Colonies of some classes have various types of non-feeding specialist zooids, some of which are hatcheries for fertilized eggs, some classes have special zooids for defense of the colony; the class Cheilostomata have the largest number of species because they have the widest range of specialist zooids. A few species can creep slowly by using spiny defensive zooids as legs. Autozooids supply nutrients to non-feeding zooids by channels. All zooids, including those of the solitary species, consist of a cystid that provides the body wall and produces the exoskeleton and a polypide that contains the internal organs and the lophophore or other specialist extensions. Zooids have no special excretory organs, the polypides of autozooids are scrapped when the polypides become overloaded by waste products. In autozooids the gut is U-shaped, with the mouth inside the "crown" of tentacles and the anus outside it. Colonies take a variety of forms, including fans and sheets.
The Cheilostomata produce mineralized exoskeletons and form single-layered sheets which encrust over surfaces. Zooids of all the freshwater species are simultaneous hermaphrodites. Although those of many marine species function first as males and as females, their colonies always contain a combination of zooids that are in their male and female stages. All species emit sperm into the water; some release ova into the water, while others capture sperm via their tentacles to fertilize their ova internally. In some species the larvae have large yolks, go to feed, settle on a surface. Others feed for a few days before settling. After settling, all larvae undergo a radical metamorphosis that destroys and rebuilds all the internal tissues. Freshwater species produce statoblasts that lie dormant until conditions are favorable, which enables a colony's lineage to survive if severe conditions kill the mother colony. Predators of marine bryozoans include nudibranchs, sea urchins, crustaceans and starfish.
Freshwater bryozoans are preyed on by snails and fish. In Thailand, many populations of one freshwater species have been wiped out by an introduced species of snail. A fast-growing invasive bryozoan off the northeast and northwest coasts of the US has reduced kelp forests so much that it has affected local fish and invertebrate populations. Bryozoans have spread diseases to fish fishermen. Chemicals extracted from a marine bryozoan species have been investigated for treatment of cancer and Alzheimer's disease, but analyses have not been encouraging. Mineralized skeletons of bryozoans first appear in rocks from the Early Ordovician period, making it the last major phylum to appear in the fossil record; this has led researchers to suspect that bryozoans arose earlier but were unmineralized, may have differed from fossilized and modern forms. Early fossils are of erect forms, but encrusting forms became dominant, it is uncertain. Bryozoans' evolutionary relationships to other phyla are unclear because scientists' view of the family tree of animals is influenced by better-known phyla.
Both morphological and molecular phylogeny analyses disagree over bryozoans' relationships with entoprocts, about whether bryozoans should be grouped with brachiopods and phoronids in Lophophorata, whether bryozoans should be considered protostomes or deuterostomes. Bryozoans and brachiopods strain food out of the water by means of a lophophore, a "crown" of hollow tentacles. Bryozoans form colonies consisting of clones called zooids that are about 0.5 millimetres long. Phoronids resemble bryozoan zooids but are 2 to 20 centimetres long and, although they grow in clumps, do not form colonies consisting of clones. Brachiopods thought to be related to bryozoans and phoronids, are distinguished by having shells rather like those of bivalves. All three of these phyla have a coelom, an internal cavity lined by mesothelium; some encrusting bryozoan colonies with mineralized exoskeletons look like small corals. However, bryozoan colonies are founded by an ancestrula, round rather than shaped like a normal zooid of that species.
On the other hand, the founding
Paracentrotus lividus is a species of sea urchin in the family Parechinidae known as the purple sea urchin. It occurs in the Mediterranean Sea and eastern Atlantic Ocean. P. lividus has a circular, flattened greenish test with a diameter of up to seven centimetres. The test is densely clothed in long and pointed spines that are purple but are other colours including dark brown, light brown and olive green. There are six pairs of pores on each ambulacral plate; the tube feet are in groups of 6, arranged in small arcs. P. lividus is found throughout the Mediterranean Sea and in the eastern Atlantic Ocean from western Scotland and Ireland to the Azores, Canary Islands and Morocco. It is most common in the western Mediterranean, the coasts of Portugal and the Bay of Biscay, where the water temperature in winter varies between 10 and 15 °C. P. lividus is found just below low water mark at depths down to twenty metres and sometimes in rock pools. It is found on rocks and boulders, in seagrass meadows of Zostera marina and Posidonia oceanica.
Although Cymodocea nodosa is a preferred food item, it is found in meadows of this seagrass because the shifting sand substrate does not suit it or because of pressure from predators. In fact it avoids soft substrates and can sometimes be found clustered on stones or shell "islands" surrounded by sand. In shallow or exposed waters it can use its mouth and spines to dig into soft rocks to create cavities into which it returns and in which it fits. Where the urchins are numerous, the rock may be honeycombed by these excavations. Smaller individuals use these retreats, which provide some protection from predators. In lagoons and rock pools, individuals are smaller. P. lividus is unable to tolerate low salinity. After exceptional quantities of rain fell in Corsica in the autumn of 1993, there was mass mortality of urchins in the Urbini Lagoon; however the urchin is unaffected by organic pollution and heavy metals, in fact it flourishes near sewage outlets. There are wide swings in population densities over its range, which have not been explained.
Individual P. lividus are either female although hermaphroditism has been observed. They aggregate for release gametes into the water column; the larvae form part of the zooplankton for about 28 days before settling and undergoing metamorphosis. P. lividus is a browser, eating a range of red and brown algae in addition to seagrass. The benthic community is much affected by the number of their food preferences. Where they are numerous they tend to be surrounded by "barren ground" colonised by encrusting Corallinaceae species and characterised by a low biomass of primary producers with a small number of associated species. Where numbers are low, there tend to be forests of Laminaria and Cystoseira and a much richer, three-dimensional community; the barren grounds can persist for years though whether this is due to overgrazing by urchins or prevention of recruitment of multicellular photosynthetic organisms by encrusting algae is unclear. Some juveniles of small fish species shelter among the spines.
These include the clingfishes Apletodon incognitus and Lepadogaster candolii and the gobies, Gobius bucchichi, Zebrus zebrus and Millerigobius macrocephalus. The main predators on P. lividus in the Mediterranean Sea are the spider crab, the fish Diplodus sargus, Diplodus vulgaris,Labrus merula and Coris julis and the gastropod, Hexaplex trunculus. The spiny starfish is a main predator elsewhere. Predation is dependent on size. In most locations the urchins are nocturnal feeders, but where predators are more active at night the urchins may feed during day instead; the gonads are considered a delicacy in Lebanon, Italy, Spain and parts of Croatia, most notably on the island of Korčula, are eaten to a lesser extent in Greece. The urchins have been harvested for export over a wider area including Croatia and Ireland
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
Sponges, the members of the phylum Porifera, are a basal Metazoa clade as a sister of the Diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through them, consisting of jelly-like mesohyl sandwiched between two thin layers of cells; the branch of zoology that studies sponges is known as spongiology. Sponges have unspecialized cells that can transform into other types and that migrate between the main cell layers and the mesohyl in the process. Sponges do not have digestive or circulatory systems. Instead, most rely on maintaining a constant water flow through their bodies to obtain food and oxygen and to remove wastes. Sponges were first to branch off the evolutionary tree from the common ancestor of all animals, making them the sister group of all other animals; the term sponge derives from the Ancient Greek word σπόγγος. Sponges are similar to other animals in that they are multicellular, lack cell walls and produce sperm cells.
Unlike other animals, they lack true organs. Some of them are radially symmetrical; the shapes of their bodies are adapted for maximal efficiency of water flow through the central cavity, where it deposits nutrients, leaves through a hole called the osculum. Many sponges have internal skeletons of spongin and/or spicules of calcium carbonate or silicon dioxide. All sponges are sessile aquatic animals. Although there are freshwater species, the great majority are marine species, ranging from tidal zones to depths exceeding 8,800 m. While most of the 5,000–10,000 known species feed on bacteria and other food particles in the water, some host photosynthesizing microorganisms as endosymbionts and these alliances produce more food and oxygen than they consume. A few species of sponge that live in food-poor environments have become carnivores that prey on small crustaceans. Most species use sexual reproduction, releasing sperm cells into the water to fertilize ova that in some species are released and in others are retained by the "mother".
The fertilized eggs form larvae to settle. Sponges are known for regenerating from fragments that are broken off, although this only works if the fragments include the right types of cells. A few species reproduce by budding; when conditions deteriorate, for example as temperatures drop, many freshwater species and a few marine ones produce gemmules, "survival pods" of unspecialized cells that remain dormant until conditions improve and either form new sponges or recolonize the skeletons of their parents. The mesohyl functions as an endoskeleton in most sponges, is the only skeleton in soft sponges that encrust hard surfaces such as rocks. More the mesohyl is stiffened by mineral spicules, by spongin fibers or both. Demosponges use spongin, in many species, silica spicules and in some species, calcium carbonate exoskeletons. Demosponges constitute about 90% of all known sponge species, including all freshwater ones, have the widest range of habitats. Calcareous sponges, which have calcium carbonate spicules and, in some species, calcium carbonate exoskeletons, are restricted to shallow marine waters where production of calcium carbonate is easiest.
The fragile glass sponges, with "scaffolding" of silica spicules, are restricted to polar regions and the ocean depths where predators are rare. Fossils of all of these types have been found in rocks dated from 580 million years ago. In addition Archaeocyathids, whose fossils are common in rocks from 530 to 490 million years ago, are now regarded as a type of sponge; the single-celled choanoflagellates resemble the choanocyte cells of sponges which are used to drive their water flow systems and capture most of their food. This along with phylogenetic studies of ribosomal molecules have been used as morphological evidence to suggest sponges are the sister group to the rest of animals; some studies have shown that sponges do not form a monophyletic group, in other words do not include all and only the descendants of a common ancestor. Recent phylogenetic analyses suggest that comb jellies rather than sponges are the sister group to the rest of animals; the few species of demosponge that have soft fibrous skeletons with no hard elements have been used by humans over thousands of years for several purposes, including as padding and as cleaning tools.
By the 1950s, these had been overfished so that the industry collapsed, most sponge-like materials are now synthetic. Sponges and their microscopic endosymbionts are now being researched as possible sources of medicines for treating a wide range of diseases. Dolphins have been observed using sponges as tools while foraging. Sponges constitute the phylum Porifera, have been defined as sessile metazoans that have water intake and outlet openings connected by chambers lined with choanocytes, cells with whip-like flagella. However, a few carnivorous sponges have lost the choanocytes. All known living sponges can remold their bodies, as most types of their cells can move within their bodies and a few can change from one type to another. If a few sponges are able to produce mucus – which acts as a microbial barrier in all other animals – no sponge with the ability to secrete a functional mucus layer has been recorded. Without such a mucus layer their living tissue is covered by a layer of microbial symbionts, which can contribute up to 40–50% of the sponge wet mass.
This inability to prevent microbes from penetrating their porous tissue could be a major reason why they have never evolved a more complex anatomy. Like cnidarians (jellyfish, e
Sterechinus is a genus of sea urchins in the family Echinidae. All living members of the genus are found in the waters around Antarctica but the first species described in the genus was a fossil and was found in Europe. Members of the genus Sterechinus have compound ambulacral plates; these plates have a primary tubercle articulating with a spine on the middle element, a small secondary tubercle in the interambulacral groove on one side of it and 3 pairs of pores on the other. The tube feet are connected to these pores in the living animal and the pore pairs are arranged in a vertical arc; the sutures between the plates are indented. The area of narrow plates around the mouth is small and the buccal notches are shallowly grooved; the type species of this genus is Stirechinus scillae, first described from a fossil by Pierre Desor in 1856. Stirechinus scillae lived from the Late Miocene to the Plio-Pleistocene and further fossils have since been found in France and Malta. None of the fossilized urchins so far discovered had any apical plates.
Since other members of the genus have been described, all from the waters around Antarctica. The World Register of Marine Species lists the following extant species in the genus: Sterechinus agassizii Mortensen, 1910 Sterechinus antarcticus Koehler, 1901 Sterechinus bernasconiae Larrain, 1975 Sterechinus dentifer Koehler, 1926 Sterechinus diadema Sterechinus neumayeri
Diatoms are a major group of algae microalgae, found in the oceans and soils of the world. Living diatoms number in the trillions: they generate about 20 percent of the oxygen produced on the planet each year, take in over 6.7 billion metric tons of silicon each year from the waters in which they live, contribute nearly half of the organic material found in the oceans. The shells of dead diatoms can reach as much as a half mile deep on the ocean floor, the entire Amazon basin is fertilized annually by 27 million tons of diatom shell dust transported by east-to-west transatlantic winds from the bed of a dried up lake once covering much of the African Sahara. Diatoms are unicellular: they occur either as solitary cells or in colonies, which can take the shape of ribbons, zigzags, or stars. Individual cells range in size from 2 to 200 micrometers. In the presence of adequate nutrients and sunlight, an assemblage of living diatoms doubles every 24 hours by asexual multiple fission. Diatoms have two distinct shapes: a few are radially symmetric, while most are broadly bilaterally symmetric.
A unique feature of diatom anatomy is that they are surrounded by a cell wall made of silica, called a frustule. These frustules have structural coloration due to their photonic nanostructure, prompting them to be described as "jewels of the sea" and "living opals". Movement in diatoms occurs passively as a result of both water currents and wind-induced water turbulence. Similar to plants, diatoms convert light energy to chemical energy by photosynthesis, although this shared autotrophy evolved independently in both lineages. Unusually for autotrophic organisms, diatoms possess a urea cycle, a feature that they share with animals, although this cycle is used to different metabolic ends in diatoms; the study of diatoms is a branch of phycology. Diatoms are classified as eukaryotes, organisms with a membrane-bound cell nucleus, that separates them from the prokaryotes archaea and bacteria. Diatoms are a type of plankton called phytoplankton, the most common of the plankton types. Diatoms grow attached to benthic substrates, floating debris, on macrophytes.
They comprise an integral component of the periphyton community. Another classification divides plankton into eight types based on size: in this scheme, diatoms are classed as microalgae. Several systems for classifying the individual diatom species exist. Fossil evidence suggests that diatoms originated during or before the early Jurassic period, about 150 to 200 million years ago. Diatoms are used to monitor past and present environmental conditions, are used in studies of water quality. Diatomaceous earth is a collection of diatom shells found in the earth's crust, they are soft, silica-containing sedimentary rocks which are crumbled into a fine powder and have a particle size of 10 to 200 μm. Diatomaceous earth is used for a variety of purposes including for water filtration, as a mild abrasive, in cat litter, as a dynamite stabilizer. Diatoms are 2 to 200 micrometers in length, their yellowish-brown chloroplasts, the site of photosynthesis, are typical of heterokonts, having four membranes and containing pigments such as the carotenoid fucoxanthin.
Individuals lack flagella, but they are present in male gametes of the centric diatoms and have the usual heterokont structure, except they lack the hairs characteristic in other groups. Diatoms are referred as "jewels of the sea" or "living opals" due to their photonic crystal properties; the biological function of this structural coloration is not clear, but it is speculated that it may be related to communication, thermal exchange and/or UV protection. Diatoms build intricate hard but porous cell walls called frustules composed of silica; this siliceous wall can be patterned with a variety of pores, minute spines, marginal ridges and elevations. The cell itself consists of two halves, each containing an flat plate, or valve and marginal connecting, or girdle band. One half, the hypotheca, is smaller than the other half, the epitheca. Diatom morphology varies. Although the shape of the cell is circular, some cells may be triangular, square, or elliptical, their distinguishing feature is a hard mineral frustule composed of opal.
Most diatoms are nonmotile, as their dense cell walls cause them to sink. Planktonic forms in open water rely on turbulent mixing of the upper layers of the oceanic waters by the wind to keep them suspended in sunlit surface waters; the only mechanism for regulating buoyancy is an ionic pump. Cells are solitary or united into colonies of various kinds, which may be linked by siliceous structures. Diatoms are photosynthetic. Diatom cells are contained within a unique silica cell wall known as a frustule made up of two valves called thecae, that overlap one another; the biogenic silica composing the cell wall is synthesised intracellularly by the polymerisation of silicic acid monomer