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 Adult Pomphorhynchus in a Bluefish (Pomatomus saltatrix)
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The Acanthocephala (Greek akanthos, thorn + kephale, head) is a phylum of parasitic worms known as acanthocephales, thorny-headed worms, or spiny-headed worms, characterised by the presence of an evertable proboscis, armed with spines, which it uses to pierce and hold the gut wall of its host. The bluefish ( Pomatomus saltatrix) called tailor in Australia, is a species of popular marine game- Fish found in all climates Eumetazoa is a Clade comprising all major Animal groups except sponges Characteristics of eumetazoans include true tissues organized into The Bilateria (ˌbaɪləˈtɪəriə are all animals having a bilateral symmetry, i The Platyzoa (ˌplætɨˈzoʊə are a group of Protostome animals proposed by Thomas Cavalier-Smith in 1998 A class is the Taxonomic rank in the Biological classification of organisms in Biology below phylum and above order. Archiacanthocephala is a class within the phylum of Acanthocephala. Palaeacanthocephala ("ancient thornheads" is a class within the Phylum Acanthocephala. Eoacanthocephala is a class of parasitic Worms within the Phylum [[Acanthocephala]] They feed on any aquatic Cold-blooded creature Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly A phylum ( Plural: phyla) is a Taxonomic rank between Kingdom and above Class. Parasitism is a type of symbiotic relationship between Organisms of different Species. In general a proboscis (from Greek προ pro "before" and βοσκειν boskein "to feed" also known as probiscus Acanthocephalans typically have complex life cycles, involving a number of hosts, including invertebrates, fishes, amphibians, birds, and mammals. Parasite life cycles can take a variety of forms all involving the exploitation of one or more hosts. An invertebrate is an Animal lacking a Vertebral column. The group includes 98% of all animal Species — all animals except those in the Chordate Fish are aquatic Vertebrate animals that are typically ectothermic (previously Cold-blooded) covered with scales, and equipped with two Prehistoric amphibian Amphibians (class Amphibia such as Frogs Toads Salamanders Newts Gymnophiona, Sirens and Birds ( class Aves) are bipedal endothermic ( Warm-blooded) Vertebrate animals that lay eggs. Mammals ( class Mammalia) are a class of Vertebrate Animals characterized by the presence of Sweat glands, including sweat glands About 1150 species have been described. In Biology, a species is one of the basic units of Biological classification and a Taxonomic rank.
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Morphological characteristics
There are several morphological characteristics that distinguish acanthocephalans from other phyla of parasitic worms.
Digestion
Acanthocephalans lack a mouth or alimentary canal. The mouth, buccal cavity, or oral cavity is the first portion of the Alimentary canal that receives food and begins digestion by mechanically breaking up This is a feature they share with the cestoda (tapeworms), although the two groups are not related. Tapeworm is also an older name for a type of Computer virus. Cestoda is a class of Parasitic Flatworms commonly called Adult stages live in the intestines of their host and uptake nutrients which have been digested by the host, directly, through their body surface. In Anatomy, the intestine is the segment of the alimentary canal extending from the Stomach to the Anus and in humans and other mammals consists
Proboscis
The most notable feature of the acanthocephala is the presence of an anterior, protrudible proboscis that is usually covered with spiny hooks (hence the common name: thorny headed worm). In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species In general a proboscis (from Greek προ pro "before" and βοσκειν boskein "to feed" also known as probiscus The proboscis bears rings of recurved hooks arranged in horizontal rows, and it is by means of these hooks that the animal attaches itself to the tissues of its host. The hooks may be of two or three shapes, usually, longer, more slender hooks are arranged along the length of the proboscis, with several rows of more sturdy, shorter nasal hooks around the base of the proboscis. The proboscis is used to pierce the gut wall of the final host, and hold the parasite fast while it completes its life cycle. Like the body, the proboscis is hollow, and its cavity is separated from the body cavity by a septum or proboscis sheath. Traversing the cavity of the proboscis are muscle-strands inserted into the tip of the proboscis at one end and into the septum at the other. Muscle (from Latin musculus, diminutive of mus "mouse" is contractile tissue of the body and is derived from the Their contraction causes the proboscis to be invaginated into its cavity. The whole proboscis apparatus can also be, at least partially, withdrawn into the body cavity, and this is effected by two retractor muscles which run from the posterior aspect of the septum to the body wall.
Phylogenetic relationships
Acanthocephalans are highly adapted to a parasitic mode of life, and have lost many organs and structures through evolutionary processes. This makes determining relationships with other higher taxa through morphological comparison problematic. Phylogenetic analysis of the 18S ribosomal gene has revealed that the Acanthocephala are most closely related to the rotifers, or may even belong in that phylum. Ribosomes ( from ribo nucleic acid and "Greek soma ( meaning body") are complexes of RNA and Protein that The rotifers make up a Phylum of microscopic and near-microscopic pseudocoelomate Animals They were first described by Rev The two are included among the Platyzoa. The Platyzoa (ˌplætɨˈzoʊə are a group of Protostome animals proposed by Thomas Cavalier-Smith in 1998
Size
The size of the animals varies greatly, from forms a few millimetres in length to Gigantorhynchus gigas, which measures from 100 to 650 mm. The Millimetre ( American spelling: millimeter, symbol mm) is a unit of Length in the Metric system, equal to
Skin
The body surface of the acanthocephala is peculiar. Externally, the skin has a thin cuticle covering the epidermis, which consists of a syncytium with no cell walls. In Biology, the term cuticle or cuticula is given to a variety of tough but flexible non-mineral outer coverings of an organism or part of an organism that In Anatomy, squamous epithelium (from Latin squama, "scale" is an Epithelium characterised by its most superficial layer consisting In Biology, a syncytium ( plural syncytia) is a large cell-like structure filled with Cytoplasm containing many nuclei A cell wall is a tough flexible and sometimes fairly rigid layer surrounding a cell, located external to the Cell membrane, which provides the cell with structural The syncytium is traversed by a series of branching tubules containing fluid and is controlled by a few wandering, amoeboid nuclei. A tubule is a very small Tube or Fistular structure A system of surface-connected membranes in muscle that enables a nerve impulse to travel to the interior of Amoeboids are Unicellular lifeforms that mainly consist of Contractile vacuoles, a nucleus, and cytoplasm as their basic structure In Cell biology, the nucleus (pl nuclei; from Latin la ''nucleus'' or la ''nuculeus'' "little nut" or kernel is a membrane-enclosed Inside the syncytium is an irregular layer of circular muscle fibres, and within this again some rather scattered longitudinal fibres; there is no endothelium. The endothelium is the thin layer of cells that line the interior surface of Blood vessels forming an interface between circulating Blood in the In their micro-structure the muscular fibres resemble those of nematodes. The nematodes or roundworms ( Phylum Nematoda from Greek (nema "thread" + -ode "like" are one of the most common
Except for the absence of the longitudinal fibres the skin of the proboscis resembles that of the body, but the fluid-containing tubules of the proboscis are shut off from those of the body. The canals of the proboscis open into a circular vessel which runs round its base. From the circular canal two sac-like projections called the lemnisci run into the cavity of the body, alongside the proboscis cavity. Each consists of a prolongation of the syncytial material of the proboscis skin, penetrated by canals and sheathed with a muscular coat. They seem to act as reservoirs into which the fluid which is used to keep the proboscis "erect" can withdraw when it is retracted, and from which the fluid can be driven out when it is wished to expand the proboscis.
Nervous system
The central ganglion of the nervous system lies behind the proboscis sheath or septum. It innervates the proboscis and projects two stout trunks posteriorly which supply the body. Each of these trunks is surrounded by muscles, and this nerve-muscle complex is called a retinaculum. In the male at least there is also a genital ganglion. A sex organ, or primary sexual characteristic, as narrowly defined is any of the anatomical parts of the body which are involved in sexual reproduction and constitute In Anatomy, a ganglion (pl ganglia) is a tissue mass. Neurology In neurological contexts ganglia are composed mainly of Some scattered papillae may possibly be sense-organs.
"Brain-jacking"
Thorny-headed worms begin their life cycle inside invertebrates that reside in lakes and rivers. Gammarus lacustris, a small crustacean that feeds near ponds and rivers, is one invertebrate that the thorny-headed worm may occupy. This crustacean is predated by ducks and hides by avoiding light and staying away from the surface. However, when infected by a thorny-headed worm it becomes attracted toward light and surfaces itself. Gammarus lacustris will even go so far as to find a rock or a plant on the surface, clamp its mouth down, and latch on, making it easy prey for the duck.
It is thought that when Gammarus lacustris is infected with a thorny-headed worm, the parasite causes serotonin to be massively expressed. Serotonin (ˌsɛrəˈtoʊnən ( 5-hydroxytryptamine, or 5-HT) is a Monoamine Neurotransmitter synthesized in serotonergic Neurons Serotonin is a neurotransmitter involved in emotions and mood. Researchers have found that during mating Gammarus lacustris expresses high levels of serotonin. Also during mating, the male Gammarus lacustris clamps down on the female and holds on for days. Researchers have additionally found that blocking serotonin releases clamping. Another experiment found that serotonin also reduces the photophobic behavior in Gammarus lacustris. Thus, it is thought that the thorny-headed worm physiologically changes the behavior of the Gammarus lacustris in order to enter its final host, the bird.
Sex
The Acanthocephala are dioecious. Plant sexuality covers the wide variety of Sexual reproduction systems found across the Plant kingdom There is a structure called the genital ligament which runs from the posterior end of the proboscis sheath to the posterior end of the body. In the male, two testes lie on either side of this. The testicle (from Latin testiculus, diminutive of testis, meaning "witness" virility plural testes) is the male Each opens in a vas deferens which bears three diverticula or vesiculae seminales. The vas deferens (plural vasa deferentia also called ductus deferens, ( Latin: "carrying-away vessel" is part of the Male Anatomy A diverticulum (plural diverticula) is medical term for an outpouching of a hollow (or a fluid filled structure in the body The male also possesses three pairs of cement glands, found behind the testes, which pour their secretions through a duct into the vasa deferentia. These unite and end in a penis which opens posteriorly. The penis (plural penises, penes
In the female, the ovaries are found, like the testes, as rounded bodies along the ligament. "Ovaria" redirects here This is also a proposed section and a Synonym of Solanum. From these masses of ova dehisce into the body cavity and float in its fluid. Here the eggs are fertilized and segment so that the young embryos are formed within their mother's body. For soil improvement see Fertilization (soil. An embryo (from Greek:, plural, lit "that which grows" from en- "in" + bryein "to swell be full" is a multicellular The embryos escape into the uterus through the uterine bell, a funnel like opening continuous with the uterus. The uterus (from the Latin word for womb) is the major Female reproductive organ of most Mammals including Humans One end the At the junction of the bell and the uterus there is a second small opening situated dorsally. In Anatomy, the dorsum is the upper side of animals that typically run fly or swim in a horizontal position and the back side of animals (like humans that walk upright The bell "swallows" the matured embryos and passes them on into the uterus, and from there, out of the body via the oviduct. Oviduct is also another name for Fallopian tube In Oviparous Animals (those that lay eggs, the passage from the ovaries Should the bell swallow any of the ova, or even one of the younger embryos, these are passed back into the body cavity through the second, dorsal, opening.
The embryo passes from the body of the female into the alimentary canal of the host and leaves this with the feces. Feces, faeces, or fæces (see spelling differences) is a waste product from an animal's digestive tract expelled through the Anus
Other features
A curious feature shared by both larva and adult is the large size of many of the cells, e. g. the nerve cells and cells forming the uterine bell. Polyploidy is common, with up to 343n having been recorded in some species. Polyploidy occurs in cells and Organisms when there are more than two homologous sets of Chromosomes. The acanthocephalans lack an excretory system, although some species have been shown to possess flame cells (protonephridia). flame cell is a specialized excretory cell found in most "lower" freshwater invertebrates including Nematode, Platyhelminthes (except the tubellarian
History
The earliest recognisable description of Acanthocephala - a worm with a proboscis armed with hooks - was made by Italian author Francesco Redi (1684). Francesco Redi (February 18/19 1626&ndash March 1, 1697) was an Italian Physician. In 1771 Koelreuther proposed the name Acanthocephala. Year 1771 ( MDCCLXXI) was a Common year starting on Tuesday (link will display the full calendar of the Gregorian calendar (or a Muller independetly called them Echinorhynchus in 1776. Year 1776 ( MDCCLXXVI) was a Leap year starting on Monday (link will display the full calendar of the Gregorian calendar (or a Rudolphi in 1809 formally named them Acanthocephala. Karl Asmund Rudolphi ( July 14, 1771 &ndash November 29, 1832) was a Swedish -born naturalist, who is credited with being Year 1809 ( MDCCCIX) was a Common year starting on Sunday (link will display the full calendar of the Gregorian calendar (or a Common year
Currently the phylum is divided into four classes - Palaeacanthocephala, Archiacanthocephala, Polyacanthocephala and Eoacanthocephala.
Life cycles
General patterns
Acanthocephalans have complex life cycles, involving a number of hosts, for both developmental and resting stages. MOrphogenesis is an EP by Industrial Black metal band.And Oceans. Complete life cycles have been worked out for only 25 species. Having been expelled by the female, the acanthocephalan embryo is released along with the feces of the host. For development to occur, the embryo needs to be ingested by an invertebrate, almost always a crustacean (there is one known life cycle which uses a mollusc as a first intermediate host). Structure of crustaceans As Arthropods crustaceans have a stiff Exoskeleton, which must be shed to allow the animal to grow ( Ecdysis or molting Molluscs are animals belonging to the phylum Mollusca. There are around 250000 extant Species within the phylum with an estimated 70000 Inside the intermediate host, the acanthocephalan penetrates the gut wall, moves into the body cavity, encysts, and begins transformation into the infective cystacanth stage. This form has all the organs of the adult save the reproductive ones. The parasite is released when the first intermediate host is ingested. This can be by a suitable final host, in which case the cystacanth develops into a mature adult, or by a paratenic host, in which the parasite again forms a cyst. In Parasitology, the term paratenic describes an intermediate host which is not needed for the development of the Parasite, but nonetheless serves to maintain the When consumed by a suitable final host, the cycstacant excysts, everts its proboscis and pierces the gut wall. It then feeds, grows and develops its sexual organs. Adult worms then mate. The male uses the excretions of its cement glands to plug the vagina of the female, preventing subsequent matings from occurring. The vagina (from Latin, literally " Sheath " or " Scabbard " is a fibromuscular tubular tract leading from the Uterus Embryos develop inside the female, and the life cycle repeats.
An example - Polymorphus spp.
Polymorphus spp. are parasites of seabirds, particularly the Eider Duck (Somateria mollissima). Seabirds are Birds that have adapted to life within the marine environment For the river see Eider River. For other uses see Eider (disambiguation. Heavy infections of up to 750 parasites per bird are common, causing ulceration to the gut, disease and seasonal mortality. Ulcers are healing wounds that develop on the skin mucous membranes or eye Recent research has suggested that there is no evidence of pathogenicity of Polymorphus spp. A pathogen (from Greek πάθος pathos "suffering passion" and γἰγνομαι (γεν- gignomai (gen- "I give birth to" infectious to intermediate crab hosts. The cystacanth stage is long lived and probably remains infective throughout the life of the crab.
The life cycle of Polymorphus spp. normally occurs between sea ducks (e. g. eiders and scoters) and small crabs. The scoters are stocky Seaducks in the Genus Melanitta. The drakes are mostly black and have swollen bills Infections found in commercial-sized lobsters in Canada were probably acquired from crabs that form an important dietary item of lobsters. Clawed lobsters compose a family ( Nephropidae, sometimes also Homaridae) of large marine Crustaceans Lobsters are economically important as Cystacanths occurring in lobsters can cause economic loss to fishermen. There are no known methods of prevention or control.
See also
References
- Lühe, M. Tapeworm is also an older name for a type of Computer virus. Cestoda is a class of Parasitic Flatworms commonly called Digenea (Gr Dis - double Genos - race is a subclass within the Platyhelminthes consisting of Parasitic Flatworms with Monogenea (adj monogenean are a group of largely ectoparasitic members of the flatworm phylum Platyhelminthes, class Monogenea. (1904). 'Geschichte und Ergebnisse der Echinorhynchen-Forschung bis auf Westrumb (1821)', Zoologische Ann. . . . Zeitschift, 1, 139-250.
- Amin, O. M. (1987). Key to the families and subfamilies of Acanthocephala, with erection of a new class (Polyacanthocephala) and a new order (Polyacanthorhynchida). Journal of Parasitology, 73, 1216-1219.
- Zimmer, C. Parasite Rex: Inside the Bizarre World of Nature's Most Dangerous Creatures 92. Carl Zimmer (born 1966 is a popular science writer and Blogger especially regarding the study of Evolution and Parasites He has written several books and IBSN-13: 978-0-7432-0011-0 ISBN-10: 0-7432-0011-X.
- Helluy & Thomas 2002 Proc. Royal.
- Tain, L, et al. "Altered Host Behavior and Brain Serotonergic Activity Caused by Acanthocephalans; Evidence for Specificity. " The Royal Society, 2006.
External links
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