Nemertea is a phylum of invertebrate animals also known as ribbon worms or proboscis worms ^[1]. Most of the 1,400 or so species are marine, with a few living in fresh water and a small number of terrestrial forms; they are found in all marine habits, and throughout the world's oceans ^[2]. Nemerteans are named for Nemertes, one of the Nereids of Greek mythology, and alternative spellings for the phylum have included Nemertini, Nemertinea and Nemertea. In biological taxonomy, a phylum (Greek plural: phyla) is a taxon in the rank below kingdom and above class. ... Invertebrate is an English word that describes any animal without a spinal column. ... For other uses, see Animal (disambiguation). ... For other uses, see Species (disambiguation). ... For the village on the Isle of Wight, see Freshwater, Isle of Wight. ... Terrestrial animals are animals that live predominantly or entirely on land, as compared with aquatic animals, which live predominantly or entirely in the water (e. ... In Greek mythology, the Nereids (NEER-ee-eds) are blue-haired sea nymphs, the fifty daughters of Nereus and Doris. ... The bust of Zeus found at Otricoli (Sala Rotonda, Museo Pio-Clementino, Vatican) Greek mythology is the body of stories belonging to the Ancient Greeks concerning their gods and heroes, the nature of the world and the origins and significance of their own cult and ritual practices. ...

Ecology and distribution

The majority of nemertean worms live on or in the sea floor, with many species extending into brackish water in estuaries, and some freshwater or fully terrestrial species. Freshwater genera include the large genus Prostoma, while the terrestrial forms are best represented by Geonemertes, a genus mostly found in Australasia, but with one species in the Seychelles, one found widely across the Indo-Pacific, one from Tristan da Cunha in the South Atlantic, and one, G. chalicophora, first found in the Palmengarten in Frankfurt, but since discovered in the Canary Islands, Madeira and the Azores ^[3]. Brackish redirects here. ... For the village on the Isle of Wight, see Freshwater, Isle of Wight. ... Terrestrial animals are animals that live predominantly or entirely on land, as compared with aquatic animals, which live predominantly or entirely in the water (e. ... Australasia Australasia is a term variably used to describe a region of Oceania: Australia, New Zealand, and neighbouring islands in the Pacific Ocean. ... The Indo-Pacific is the aggregate of the Indian Ocean, Pacific Ocean, and the minor seas between the two in the general area of Indonesia. ... Motto Our faith is our strength Anthem God Save the Queen Capital (and largest city) Edinburgh of the Seven Seas Official languages English Government Dependency of St. ... The Palmengarten is one of two botanical gardens in Frankfurt am Main and is located in the city district Westend-Süd. ... For other uses, see Frankfurt (disambiguation). ... Anthem: Arrorró Capital Las Palmas de Gran Canaria and Santa Cruz de Tenerife Official language(s) Spanish Area  â€“ Total  â€“ % of Spain Ranked 13th  7,447 km²  1. ... For other uses, see Madeira (disambiguation). ... Motto (Portuguese for Rather die free than in peace subjugated) Anthem  (national)  (local) Capital Ponta Delgada1 Angra do Heroísmo2 Horta3 Largest city Ponta Delgada Official languages Portuguese Government Autonomous region  -  President Carlos César Establishment  -  Settled 1439   -  Autonomy 1976  Area  -  Total 2,333 km² (n/a) 911 sq mi...

They are often found in and among seaweeds, rocks, mussel and barnacle beds, or buried in mud, sand, or gravel substrates. Ascophyllum nodosum exposed to the sun in Nova Scotia, Canada Dead Mans Fingers (Codium fragile) off Massachusetts coast For the band, see; Seaweed (band) For the rock musician, see; Seaweed (musician) Seaweeds are any of a large number of marine benthic algae. ... Rock redirects here. ... Subclasses Pteriomorpha (marine mussels) Palaeoheterodonta (freshwater mussels) Heterodonta (zebra mussels) The term mussel is used for several families of bivalve molluscs inhabiting lakes, rivers, and creeks, as well as intertidal areas along coastlines worldwide. ... For other uses, see Barnacle (disambiguation). ...

Most nemerteans are carnivorous and predatory, catching prey with their proboscis ^[4], although some are scavengers and some are herbivores ^[5]. In some families, it is armed with a sharp stylet which may be poisonous, while those that lack the stylet often use a sticky secretion on the proboscis to entrap their prey. The proboscis is wrapped around the prey, which is normally other invertebrates such as crustaceans and annelids and can be many times larger than the nemertean itself, and the prey is then stabbed repeatedly with the stylet until dead ^[6]. A few, such as Malacobdella, live parasitically in the mantle cavity of molluscs and live on the food filtered by their hosts ^[6]. This snapping turtle is trying to make a meal of a Canada goose, but the goose is too wary. ... For a person who scavenges, see Waste picker. ... A deer and two fawns feeding on some foliage A herbivore is often defined as any organism that eats only plants[1]. By that definition, many fungi, some bacteria, many animals, about 1% of flowering plants and some protists can be considered herbivores. ... For the Dutch band, see Crustacean (band). ... Classes and subclasses Class Polychaeta (paraphyletic?) Class Clitellata*    Oligochaeta - earthworms, etc. ... The mantle is an organ found in mollusks. ... Classes Caudofoveata Aplacophora Polyplacophora - Chitons Monoplacophora Bivalvia - Bivalves Scaphopoda - Tusk shells Gastropoda - Snails and Slugs Cephalopoda - Squids, Octopuses, etc. ...

Anatomy

Nemertean worms are long, thin, unsegmented animals. They are distinguished by the presence of an eversible proboscis which is used for catching prey. Although generally considered acoelomate, the cavity which contains the proboscis includes a true coelom ^[7]. The circulatory system of nemerteans is closed, as is the digestive system, which includes separate mouth and anus (unlike flatworms, which have a single opening). The nervous system includes a brain and several nerve cords; respiration is entirely by diffusion ^[4]. In general, a proboscis (from Greek pro before and boskein to feed) is an elongated appendage from the head of an animal. ... Acoelomates consist of two modern phyla of worms -- the Platyhelminthes and Nemerteans. ... A body cavity is an aspect of a number of basic animal body plans (phyla) that incorporate a central body cavity, known as a coelom. ... For transport in plants, see Vascular tissue. ... what was here was sick and improperly spelled. ... For other uses, see Mouth (disambiguation). ... This article is about the bodily orifice. ... Classes Monogenea Trematoda Cestoda Turbellaria Wikimedia Commons has media related to: Platyhelminthes Wikispecies has information related to: Platyhelminthes The flatworms (Phylum Platyhelminthes from the Greek platy, meaning flat and helminth, meaning worm) are a phylum of relatively simple soft-bodied invertebrate animals. ... The Human Nervous System. ... The human brain In animals, the brain (enkephalos) (Greek for in the skull), is the control center of the central nervous system, responsible for behavior. ... In animal physiology, respiration is the transport of oxygen from the ambient air to the tissue cells and the transport of carbon dioxide in the opposite direction. ... diffusion (disambiguation). ...

Nemertean worms are unique in possessing a "cerebral organ" — a sensory and regulatory organ closely associated with the brain ^[2].

Nemerteans often have numerous gonads, and most species have separate sexes, although all the freshwater forms are hermaphroditic. Fertilisation is usually external, although some species have both internal fertilisation and live birth ^[2]. The gonad is the organ that makes gametes. ... The 1st-century BC sculpture The Reclining Hermaphrodite, in the Museo Nazionale Romano, Palazzo Massimo Alle Terme in Rome A hermaphrodite is an organism that possesses both male and female sex organs during its life. ... A sperm cell fertilizing an ovum This article is about reproduction in organisms. ... External fertilization is a form of fertilization in which a sperm cell is united with an egg cell external to the body of the female. ... Internal fertilization is a form of animal fertilization of an ovum by spermatozoon within the body of an inseminated animal, whether female or hermaphroditic. ... A live birth of a human being occurs when a fetus is expelled and separated from the mothers body and subsequently shows some sign of life, such as voluntary movement, heartbeat, or pulsation of the umbilical cord, but for however brief thistime. ...

Length

Nemerteans range in size from 5 mm to over 30 metres long in the case of the European Lineus longissimus. There are also reports of specimens up to 50 m or 60 m long, which would make it the longest animal in the world ^[8]; the next longest animal on record is a female blue whale, 29.9 m long ^[9]. A millimetre (American spelling: millimeter, symbol mm) is an SI unit of length that is equal to one thousandth of a metre. ... This article is about the unit of length. ... Binomial name Lineus longissimus (Gunnerus, 1770) The bootlace worm (Lineus longissimus) is in the phylum Nemertea or ribbon worms. ... Binomial name (Linnaeus, 1758) Blue Whale range Subspecies B. m. ...

Classification

The earliest record of a nemertean worm is probably an account by Olaus Magnus in 1555 of a long, greyish-blue marine worm, which is probably Lineus longissimus, but the first species was not formally described until Gunnerus described the same species (as Ascaris longissima) in 1770 ^[3]. In 1995, a total of 1,149 species had been described, and grouped into 250 genera ^[3]. Olaus Magnus, or Magni (Magnus, Latin for the Swedish Stora -- great -- is the family name, and not a personal epithet), reported as born in October 1490 in Linköping, and died on August 1, 1557, was a Swedish ecclesiastic and writer, who did pioneering work for the interest of Nordic... Binomial name Lineus longissimus (Gunnerus, 1770) The bootlace worm (Lineus longissimus) is in the phylum Nemertea or ribbon worms. ... Johan Ernst Gunnerus Johan Ernst Gunnerus (1718 - September 23, 1773) was a Norwegian bishop and botanist. ...

The fossil record of the phylum is sparse, as expected for a group of soft-bodied animals, but even the hard stylets are not found. The only possible nemertean fossil is Archisymplectes from the Mazon Creek biota of the Pennsylvanian of Illinois ^[6]. It has been suggested that this article or section be merged into Fossil. ... The Mazon Creek fossils are conservation lagerstätten found near Chicago, Illinois. ... The Pennsylvanian is an epoch of the Carboniferous period lasting from roughly 325 Ma to 299 Ma (million years ago). ... Official language(s) English[1] Capital Springfield Largest city Chicago Largest metro area Chicago Metropolitan Area Area  Ranked 25th  - Total 57,918 sq mi (140,998 km²)  - Width 210 miles (340 km)  - Length 390 miles (629 km)  - % water 4. ...

Once classified as "degenerate" flatworms, nemerteans are now recognised as a separate phylum, more closely related to higher, coelomate phyla in Lophotrochozoa, such as Annelida and Mollusca ^[10]. Classes Monogenea Trematoda Cestoda Turbellaria Wikimedia Commons has media related to: Platyhelminthes Wikispecies has information related to: Platyhelminthes The flatworms (Phylum Platyhelminthes from the Greek platy, meaning flat and helminth, meaning worm) are a phylum of relatively simple soft-bodied invertebrate animals. ... Phyla Trochozoa Mollusca Annelida Sipuncula Nemertea Lophophorata Brachiopoda Phoronida Bryozoa Entoprocta The Lophotrochozoa are one of two or three major groups of protostome animals. ... Classes and subclasses Class Polychaeta (paraphyletic?) Class Clitellata    Oligochaeta - Earthworms and others    Acanthobdellida    Branchiobdellida    Hirudinea - Leeches Class Myzostomida Class Archiannelida (polyphyletic) Class Echiura *Some authors consider the subclasses under Clitellata to be classes The annelids, collectively called Annelida, are a large phylum of animals, comprising the segmented worms, with about... Classes Caudofoveata Aplacophora Polyplacophora Monoplacophora Bivalvia Scaphopoda Gastropoda Cephalopoda † Rostroconchia † Helcionelloida † ?Bellerophontidae The molluscs (British spelling) or mollusks (American spelling) are members of the large and diverse phylum Mollusca, which includes a variety of familiar animals well-known for their decorative shells or as seafood. ...

The traditional classes of Enopla for nemerteans armed with one or more stylets and Anopla for those without are not monophyletic is not supported by molecular data ^[11]. Similarly, the subclass Bdellonemertea, erected for nemerteans which live as parasites on molluscs, is nested within Hoplonemertea, and probably represents a specislised offshoot from that group rather than an independent lineage ^[11]. Recent molecular phylogenetic study has, however, confirmed the monophyly of each of Heteronemertea and Hoplonemertea, as well as the expected paraphyly of Palaeonemertea ^[12]. Orders Hoplonemertea Bdellonemertea Enopla is one of the classes of the worm phylum Nemertea, characterized by the presence of a peculiar armature of spines or plates in the proboscis. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... In phylogenetics, a group is monophyletic (Greek: of one race) if it consists of an inferred common ancestor and all its descendants. ... Molecular phylogeny is the use of the structure of molecules to gain information on an organisms evolutionary relationships. ... In phylogenetics, a group is monophyletic (Greek: of one race) if it consists of an inferred common ancestor and all its descendants. ... Heteronemertea is a monophyletic grouping of about 500 species, containing genera such as Lineus and Cerebratulus and including the largest and most muscular nemerteans. ... In phylogenetics, a grouping of organisms is said to be paraphyletic (Greek para = near and phyle = race) if all the members of the group have a common ancestor, but the group does not include all the descendants of the most recent common ancestor of all group members. ... Families Carinomidae Cephalothricidae Hubrechtidae Tubulanidae Palaeonemertea may be a para- or polyphyletic Order, consisting of 3 to 5 clades and totalling about 100 species. ...

References