A chordate is an animal constituting the phylum Chordata. During some period of their life cycle, chordates possess a notochord, a dorsal nerve cord, pharyngeal slits, an endostyle, a post-anal tail: these five anatomical features define this phylum. Chordates are bilaterally symmetric; the Chordata and Ambulacraria together form the superphylum Deuterostomia. Chordates are divided into three subphyla: Vertebrata. There are extinct taxa such as the Vetulicolia. Hemichordata has been presented as a fourth chordate subphylum, but now is treated as a separate phylum: hemichordates and Echinodermata form the Ambulacraria, the sister phylum of the Chordates. Of the more than 65,000 living species of chordates, about half are bony fish that are members of the superclass Osteichthyes. Chordate fossils have been found from as early as the Cambrian explosion, 541 million years ago. Cladistically, vertebrates - chordates with the notochord replaced by a vertebral column during development - are considered to be a subgroup of the clade Craniata, which consists of chordates with a skull.
The Craniata and Tunicata compose the clade Olfactores. Chordates form a phylum of animals that are defined by having at some stage in their lives all of the following anatomical features: A notochord, a stiff rod of cartilage that extends along the inside of the body. Among the vertebrate sub-group of chordates the notochord develops into the spine, in wholly aquatic species this helps the animal to swim by flexing its tail. A dorsal neural tube. In fish and other vertebrates, this develops into the spinal cord, the main communications trunk of the nervous system. Pharyngeal slits; the pharynx is the part of the throat behind the mouth. In fish, the slits are modified to form gills, but in some other chordates they are part of a filter-feeding system that extracts particles of food from the water in which the animals live. Post-anal tail. A muscular tail that extends backwards behind the anus. An endostyle; this is a groove in the ventral wall of the pharynx. In filter-feeding species it produces mucus to gather food particles, which helps in transporting food to the esophagus.
It stores iodine, may be a precursor of the vertebrate thyroid gland. There are soft constraints that separate chordates from certain other biological lineages, but are not part of the formal definition: All chordates are deuterostomes; this means. All chordates are based on a bilateral body plan. All chordates are coelomates, have a fluid filled body cavity called a coelom with a complete lining called peritoneum derived from mesoderm; the following schema is from the third edition of Vertebrate Palaeontology. The invertebrate chordate classes are from Fishes of the World. While it is structured so as to reflect evolutionary relationships, it retains the traditional ranks used in Linnaean taxonomy. Phylum Chordata †Vetulicolia? Subphylum Cephalochordata – Class Leptocardii Clade Olfactores Subphylum Tunicata – Class Ascidiacea Class Thaliacea Class Appendicularia Class Sorberacea Subphylum Vertebrata Infraphylum incertae sedis Cyclostomata Superclass'Agnatha' paraphyletic Class Myxini Class Petromyzontida or Hyperoartia Class †Conodonta Class †Myllokunmingiida Class †Pteraspidomorphi Class †Thelodonti Class †Anaspida Class †Cephalaspidomorphi Infraphylum Gnathostomata Class †Placodermi Class Chondrichthyes Class †Acanthodii Superclass Osteichthyes Class Actinopterygii Class Sarcopterygii Superclass Tetrapoda Class Amphibia Class Sauropsida Class Synapsida Craniates, one of the three subdivisions of chordates, all have distinct skulls.
They include the hagfish. Michael J. Benton commented that "craniates are characterized by their heads, just as chordates, or all deuterostomes, are by their tails". Most craniates are vertebrates; these consist of a series of bony or cartilaginous cylindrical vertebrae with neural arches that protect the spinal cord, with projections that link the vertebrae. However hagfish have incomplete braincases and no vertebrae, are therefore not regarded as vertebrates, but as members of the craniates, the group from which vertebrates are thought to have evolved; however the cladistic exclusion of hagfish from the vertebrates is controversial, as they ma
Reed beds are natural habitats found in floodplains, waterlogged depressions, estuaries. Reed beds are part of a succession from young reeds colonising open water or wet ground through a gradation of dry ground; as reed beds age, they build up a considerable litter layer that rises above the water level and that provides opportunities for scrub or woodland invasion. Artificial reed beds are used to remove pollutants from grey water. Reed beds vary in the species that they can support, depending upon water levels within the wetland system, seasonal variations, the nutrient status and salinity of the water. Reed swamps have 20 cm or more of surface water during the summer and have high invertebrate and bird species use. Reed fens have water levels at or below the surface during the summer and are more botanically complex. Reeds and similar plants do not grow in acidic water. Although common reeds are characteristic of reed beds, not all vegetation dominated by this species is characteristic of reed beds.
It commonly occurs in unmanaged, damp grassland and as an understorey in certain types of damp woodland. Most European reed beds comprise Phragmites australis but include many other tall monocotyledons adapted to growing in wet conditions – other grasses such as reed sweet-grass, Canary reed-grass and small-reed, large sedges, yellow flag iris, reed-mace, water-plantains, flowering rush. Many dicotyledons occur, such as water mint, skull-cap, touch-me-not balsam and water forget-me-nots. Many animals are adapted to living around reed-beds; these include mammals such as Eurasian otter, European beaver, water vole, Eurasian harvest mouse and water shrew, birds such as great bittern, purple heron, European spoonbill, water rail, purple gallinule, marsh harrier, various warblers, bearded reedling and reed bunting. Constructed wetlands are artificial swamps using reed or other marshland plants to form part of small-scale sewage treatment systems. Water trickling through the reed bed is cleaned by microorganisms living on the root system and in the litter.
These organisms utilize the sewage for growth nutrients. The process is similar to aerobic conventional sewage treatment, as the same organisms are used, except that conventional treatment systems require artificial aeration. Treatment ponds are small versions of constructed wetlands which uses reed beds or other marshland plants to form an smaller water treatment system. Similar to constructed wetlands, water trickling through the reed bed is cleaned by microorganisms living on the root system and in the litter. Treatment ponds are used for the water treatment of a small neighbourhood. Organisms used in water purification South Milton Ley
Old English, or Anglo-Saxon, is the earliest historical form of the English language, spoken in England and southern and eastern Scotland in the early Middle Ages. It was brought to Great Britain by Anglo-Saxon settlers in the mid-5th century, the first Old English literary works date from the mid-7th century. After the Norman conquest of 1066, English was replaced, for a time, as the language of the upper classes by Anglo-Norman, a relative of French; this is regarded as marking the end of the Old English era, as during this period the English language was influenced by Anglo-Norman, developing into a phase known now as Middle English. Old English developed from a set of Anglo-Frisian or Ingvaeonic dialects spoken by Germanic tribes traditionally known as the Angles and Jutes; as the Anglo-Saxons became dominant in England, their language replaced the languages of Roman Britain: Common Brittonic, a Celtic language, Latin, brought to Britain by Roman invasion. Old English had four main dialects, associated with particular Anglo-Saxon kingdoms: Mercian, Northumbrian and West Saxon.
It was West Saxon that formed the basis for the literary standard of the Old English period, although the dominant forms of Middle and Modern English would develop from Mercian. The speech of eastern and northern parts of England was subject to strong Old Norse influence due to Scandinavian rule and settlement beginning in the 9th century. Old English is one of the West Germanic languages, its closest relatives are Old Frisian and Old Saxon. Like other old Germanic languages, it is different from Modern English and difficult for Modern English speakers to understand without study. Old English grammar is similar to that of modern German: nouns, adjectives and verbs have many inflectional endings and forms, word order is much freer; the oldest Old English inscriptions were written using a runic system, but from about the 9th century this was replaced by a version of the Latin alphabet. Englisc, which the term English is derived from, means'pertaining to the Angles'. In Old English, this word was derived from Angles.
During the 9th century, all invading Germanic tribes were referred to as Englisc. It has been hypothesised that the Angles acquired their name because their land on the coast of Jutland resembled a fishhook. Proto-Germanic *anguz had the meaning of'narrow', referring to the shallow waters near the coast; that word goes back to Proto-Indo-European *h₂enǵʰ- meaning'narrow'. Another theory is that the derivation of'narrow' is the more connection to angling, which itself stems from a Proto-Indo-European root meaning bend, angle; the semantic link is the fishing hook, curved or bent at an angle. In any case, the Angles may have been called such because they were a fishing people or were descended from such, therefore England would mean'land of the fishermen', English would be'the fishermen's language'. Old English was not static, its usage covered a period of 700 years, from the Anglo-Saxon settlement of Britain in the 5th century to the late 11th century, some time after the Norman invasion. While indicating that the establishment of dates is an arbitrary process, Albert Baugh dates Old English from 450 to 1150, a period of full inflections, a synthetic language.
Around 85 per cent of Old English words are no longer in use, but those that survived are basic elements of Modern English vocabulary. Old English is a West Germanic language, it came to be spoken over most of the territory of the Anglo-Saxon kingdoms which became the Kingdom of England. This included most of present-day England, as well as part of what is now southeastern Scotland, which for several centuries belonged to the Anglo-Saxon kingdom of Northumbria. Other parts of the island – Wales and most of Scotland – continued to use Celtic languages, except in the areas of Scandinavian settlements where Old Norse was spoken. Celtic speech remained established in certain parts of England: Medieval Cornish was spoken all over Cornwall and in adjacent parts of Devon, while Cumbric survived to the 12th century in parts of Cumbria, Welsh may have been spoken on the English side of the Anglo-Welsh border. Norse was widely spoken in the parts of England which fell under Danish law. Anglo-Saxon literacy developed after Christianisation in the late 7th century.
The oldest surviving text of Old English literature is Cædmon's Hymn, composed between 658 and 680. There is a limited corpus of runic inscriptions from the 5th to 7th centuries, but the oldest coherent runic texts date to the 8th century; the Old English Latin alphabet was introduced around the 9th century. With the unification of the Anglo-Saxon kingdoms by Alfred the Great in the 9th century, the language of government and literature became standardised around the West Saxon dialect. Alfred advocated education in English alongside Latin, had many works translated into the English language. In Old English, typical of the development of literature, poetry arose before prose, but King Alfred the Great chiefly inspired the growth of prose. A literary standard, dating from the 10th century, arose under the influence of Bishop Æthelwold of Winchester, was followed by such writers as the prolific Ælfric of Eynsham. Th
The zigzag heron is a species of heron in the family Ardeidae including egrets and bitterns. It is in the monotypic genus Zebrilus, it is found in Bolivia, Colombia, French Guiana, Peru and Venezuela. Its natural habitat is tropical swamps; the zigzag heron is a species of the entire Amazon Basin, east of the Andes cordillera, the five bordering countries on the basin's western periphery, Venezuela, Ecuador and Bolivia. The range does not extend beyond the Orinoco River basin of Venezuela in the northwest, in the east-northeast encompasses the Guianas, they are reclusive birds, staying hidden in thick cover while foraging. The adult plumage is gray with fine zigzag barring, with a pale underside, standing about 32 cm in height. Juveniles have a dark back with underside. Due to its appearance it was assigned to the tiger herons, but in fact, it is a true bittern, having like these only 10 rectrices and being unequivocally placed in the bittern lineage by DNA sequence data too. Short legs and necks and cryptic plumage may thus be plesiomorphic among Ardeidae in general.
Media related to Zebrilus undulatus at Wikimedia Commons Data related to Zigzag heron at Wikispecies Zigzag heron videos on the Internet Bird Collection Zigzag heron photo gallery VIREO Photo-high res Photo-high res PhotoArticle - sunbirdtours
The stripe-backed bittern is a species of heron in the family Ardeidae, found in South America and Trinidad. The stripe-backed bittern is small, averaging around 30 cm in length, it is darker brown with a white and brown striped pattern along the back, a black stripe from head to tail, while the underbelly is lighter brown and striped with white. This bittern calls through gargling; the stripe-backed bittern is distributed in large patches across South America, located in Colombia, Guyana, French Guiana and the island of Trinidad to the north, in Paraguay, Argentina and Brazil to the south, inhabiting reed-beds and sedge. The stripe-backed bittern is a solitary animal, it feeds at night on small fish and insects such as dragonflies and water beetles. It is not a strong flier, only does so across short distances; when threatened, it responds by pointing its neck and bill skyward, a characteristic posture of bitterns. The stripe-backed bittern makes small nests of reeds and stems, which are found above water level, among reeds.
The clutch consists of three eggs. Incubation period for eggs is unknown, breeding seasons appear to vary based on location; this bittern is considered to be of least concern due to its wide range, large, stable population. Ffrench, Richard. A Guide to the Birds of Trinidad and Tobago. Comstock Publishing. ISBN 0-8014-9792-2. Junge, G. C. A.. F.. Avifauna of Trinidad and Tobago. E. J. Brill. Kushlan, James A.. Herons. Oxford University Press. ISBN 0-19-854981-4. Martínez-Vilalta, A.. M.. "Stripe-backed Bittern". Handbook of the Birds of the World Alive. Lynx Edicions. Retrieved 24 February 2015. "Ixobrychus involucris". Cornell Lab of Ornithology. Retrieved 24 February 2015
The herons are long-legged freshwater and coastal birds in the family Ardeidae, with 64 recognised species, some of which are referred to as egrets or bitterns rather than herons. Members of the genera Botaurus and Ixobrychus are referred to as bitterns, together with the zigzag heron, or zigzag bittern, in the monotypic genus Zebrilus, form a monophyletic group within the Ardeidae. Egrets are not a biologically distinct group from the herons, tend to be named differently because they are white or have decorative plumes in breeding plumage. Herons, by evolutionary adaptation, have long beaks; the classification of the individual heron/egret species is fraught with difficulty, no clear consensus exists about the correct placement of many species into either of the two major genera and Egretta. The relationships of the genera in the family are not resolved. However, one species considered to constitute a separate monotypic family, the Cochlearidae or the boat-billed heron, is now regarded as a member of the Ardeidae.
Although herons resemble birds in some other families, such as the storks, ibises and cranes, they differ from these in flying with their necks retracted, not outstretched. They are one of the bird groups that have powder down; some members of this group nest colonially in trees, while others, notably the bitterns, use reed beds. The herons are medium - to large-sized birds with long necks, they exhibit little sexual dimorphism in size. The smallest species is considered the little bittern, which can measure under 30 cm in length, although all the species in the genus Ixobrychus are small and many broadly overlap in size; the largest species of heron is the goliath heron. The necks are able to kink in an S-shape, due to the modified shape of the cervical vertebrae, of which they have 20–21; the neck is able to retract and extend, is retracted during flight, unlike most other long-necked birds. The neck is longer in the day herons than the night bitterns; the legs are long and strong and in every species are unfeathered from the lower part of the tibia.
In flight, the legs and feet are held backward. The feet of herons have thin toes, with three forward-pointing ones and one pointing backward; the bill is long and harpoon-like. It can vary from fine, as in the agami heron, to thick as in the grey heron; the most atypical bill is owned by the boat-billed heron, which has a thick bill. The bill, as well as other bare parts of the body, is yellow, black, or brown in colour, although this can vary during the breeding season; the wings are broad and long, exhibiting 10 or 11 primary feathers, 15–20 secondaries. and 12 rectrices. The feathers of the herons are soft and the plumage is blue, brown, grey, or white, can be strikingly complex. Amongst the day herons, little sexual dimorphism in plumage is seen. Many species have different colour morphs. In the Pacific reef heron, both dark and light colour morphs exist, the percentage of each morph varies geographically. White morphs only occur in areas with coral beaches; the herons are a widespread family with a cosmopolitan distribution.
They exist on all continents except Antarctica, are present in most habitats except the coldest extremes of the Arctic high mountains, the driest deserts. All species are associated with water, they are predominantly found in lowland areas, although some species live in alpine areas, the majority of species occurs in the tropics. The herons are a mobile family, with most species being at least migratory; some species are migratory, for example the grey heron, sedentary in Britain, but migratory in Scandinavia. Birds are inclined to disperse after breeding, but before the annual migration, where the species is colonial, searching out new feeding areas and reducing the pressures on feeding grounds near the colony; the migration occurs at night as individuals or in small groups. The herons and bitterns are carnivorous; the members of this family are associated with wetlands and water, feed on a variety of live aquatic prey. Their diet includes a wide variety of aquatic animals, including fish, amphibians, crustaceans and aquatic insects.
Individual species may be generalists or specialise in certain prey types, such as the yellow-crowned night heron, which specialises in crustaceans crabs. Many species opportunistically take larger prey, including birds and bird eggs and more carrion. More herons eating acorns and grains have been reported, but most vegetable matter consumed is accidental; the most common hunting technique is for the bird to sit motionless on the edge of or standing in shallow water and to wait until prey comes within range. Birds may either do this from an upright posture, giving them a wider field of view for seeing prey, or from a crouched position, more cryptic and means the bill is closer to the prey when it is located. Having seen prey, the head is moved from side to side, so that the heron can calculate the position of the prey in the water and compensate for refraction, the bill is used to spear the prey. In addition to sitting and waiting, herons may feed more actively, they may walk around or l