Thyonicola americana is a species of parasitic sea snail, a marine gastropod mollusc in the family Eulimidae. It infests the sea cucumbers Eupentacta quinquesemita and Eupentacta pseudoquinquesemita in Puget Sound and other parts of the northeastern Pacific Ocean.
In biology, a species ( ) is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. While these definitions may seem adequate, when looked at more closely they represent problematic species concepts. For example, the boundaries between closely related species become unclear with hybridisation, in a species complex of hundreds of similar microspecies, and in a ring species. Also, among organisms that reproduce only asexually, the concept of a reproductive species breaks down, and each clone is potentially a microspecies.
In evolutionary biology, parasitism is a relationship between species, where one organism, the parasite, lives on or in another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has characterised parasites as "predators that eat prey in units of less than one". Parasites include protozoans such as the agents of malaria, sleeping sickness, and amoebic dysentery; animals such as hookworms, lice, mosquitoes, and vampire bats; fungi such as honey fungus and the agents of ringworm; and plants such as mistletoe, dodder, and the broomrapes. There are six major parasitic strategies of exploitation of animal hosts, namely parasitic castration, directly transmitted parasitism, trophically transmitted parasitism, vector-transmitted parasitism, parasitoidism, and micropredation.
Sea snail is a common name for snails that normally live in salt water, in other words marine gastropods. The taxonomic class Gastropoda also includes snails that live in other habitats, such as land snails and freshwater snails. Many species of sea snails are edible and exploited as food sources by humans.
The adult female Thyonicola americana bears little resemblance to a mollusc, having no shell and a coiled worm-like form.While living in the visceral tissues of its host, its central cavity is connected to the large intestine lumen of its host by a thin stalk, inside which is a tubule lined with cilia. The larvae are recognisable as mollusc larvae and have a shell and foot but no velum. They are benthic and move by crawling.
In biology, a lumen is the inside space of a tubular structure, such as an artery or intestine. It comes from Latin lumen, meaning 'an opening'.
Benthos is the community of organisms that live on, in, or near the seabed, also known as the benthic zone. This community lives in or near marine sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths.
A female T. americana larva settles on a suitable host and undergoes metamorphosis into a juvenile which makes its way into the host's gut, possibly through the cloaca, and penetrates the gut wall. The adult female is a worm-like organism which when uncurled can be up to 200 mm (8 in) long. The male larva enters the central cavity of the adult female and undergoes metamorphosis into a dwarf adult; it then atrophies apart from its testicular tissues which fertilise the eggs produced by the female. After taking about six months to mature, the parasite can reproduce continually, reaching peak reproduction in late summer. As it matures, the ovaries develop and the interior cavity begins to accumulate egg capsules containing eggs and developing larvae. There may be about 500 capsules each containing 75 to 150 larvae. The larvae are liberated into the host's gut sequentially as they mature. In the autumn, most host sea cucumbers eviscerate, growing a new gut in the spring. Not all individuals eviscerate, but when this occurs, the parasite is expelled (due to its attachment to the gut wall) and dies, and any remaining egg capsules are liberated into the open sea. The parasite seems to be present only in sea cucumbers with entire guts, and more than one parasite may be present in one host.
In biology and medicine, a host is an organism that harbours a parasitic, a mutualistic, or a commensalist guest (symbiont), the guest typically being provided with nourishment and shelter. Examples include animals playing host to parasitic worms, cells harbouring pathogenic (disease-causing) viruses, a bean plant hosting mutualistic (helpful) nitrogen-fixing bacteria. More specifically in botany, a host plant supplies food resources to micropredators, which have an evolutionarily stable relationship with their hosts similar to ectoparasitism. The host range is the collection of hosts that an organism can use as a partner.
Metamorphosis is a biological process by which an animal physically develops after birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Metamorphosis is iodothyronine-induced and an ancestral feature of all chordates. Some insects, fishes, amphibians, mollusks, crustaceans, cnidarians, echinoderms, and tunicates undergo metamorphosis, which is often accompanied by a change of nutrition source or behavior. Animals that go through metamorphosis are called metamorphoses. Animals can be divided into species that undergo complete metamorphosis ("holometaboly"), incomplete metamorphosis ("hemimetaboly"), or no metamorphosis ("ametaboly").
In animal anatomy, a cloacakloh-AY-kə is the posterior orifice that serves as the only opening for the digestive, reproductive, and urinary tracts of many vertebrate animals, opening at the vent. All amphibians, birds, reptiles, and a few mammals have this orifice, from which they excrete both urine and feces; this is in contrast to most placental mammals, which have two or three separate orifices for evacuation. Excretory openings with analogous purpose in some invertebrates are also sometimes referred to as cloacae. Mating by cloaca is known as cloacal copulation, mostly referred to as cloacal kiss.
The adult T. americana lives attached to the hind third of the intestine of the sea cucumber Eupentacta quinquesemita , a common holothurian in the Pacific Northwest,and also to the closely related Eupentacta pseudoquinquesemita ; in Puget Sound, 38% of the latter were found to be parasitised. E. quinquesemita exhibits a seasonal evisceration, expelling its guts in the autumn and growing a new set in the spring. However evisceration of the host results in the death of the parasite, and when this happens many individuals will not have reached full maturity and will fail to complete their life cycles.
Eupentacta quinquesemita is a species of sea cucumber, a marine invertebrate with an elongated body, a leathery skin and tentacles surrounding the mouth. It is commonly known as the stiff-footed sea cucumber or white sea cucumber, and occurs on rocky coasts in the northeastern Pacific Ocean.
Puget Sound is a sound along the northwestern coast of the U.S. state of Washington, an inlet of the Pacific Ocean, and part of the Salish Sea. It is a complex estuarine system of interconnected marine waterways and basins, with one major and two minor connections to the open Pacific Ocean via the Strait of Juan de Fuca—Admiralty Inlet being the major connection and Deception Pass and Swinomish Channel being the minor.
Evisceration is a method of autotomy involving the ejection of internal organs used by animals as a defensive strategy. Sea cucumbers (Holothuroidea) eject parts of the gut in order to scare and defend against potential predators such as crabs and fish. The organs are regenerated in a few days by cells in the interior of the sea cucumber.
Acanthocephala is a phylum of parasitic worms known as acanthocephalans, thorny-headed worms, or spiny-headed worms, characterized by the presence of an eversible proboscis, armed with spines, which it uses to pierce and hold the gut wall of its host. Acanthocephalans have complex life cycles, involving at least two hosts, which may include invertebrates, fish, amphibians, birds, and mammals. About 1420 species have been described.
Hymenolepiasis is infestation by one of two species of tapeworm: Hymenolepis nana or H. diminuta. Alternative names are dwarf tapeworm infection and rat tapeworm infection. The disease is a type of helminthiasis which is classified as a neglected tropical disease.
A veliger is the planktonic larva of many kinds of sea snails and freshwater snails, as well as most bivalve molluscs (clams) and tusk shells.
Taenia saginata, commonly known as the beef tapeworm, is a zoonotic tapeworm belonging to the order Cyclophyllidea and genus Taenia. It is an intestinal parasite in humans causing taeniasis and cysticercosis in cattle. Cattle are the intermediate hosts, where larval development occurs, while humans are definitive hosts harbouring the adult worms. It is found globally and most prevalently where cattle are raised and beef is consumed. It is relatively common in Africa, Europe, Southeast Asia, South Asia, and Latin America. Humans are generally infected as a result of eating raw or undercooked beef which contains the infective larvae, called cysticerci. As hermaphrodites, each body segment called proglottid has complete sets of both male and female reproductive systems. Thus, reproduction is by self-fertilisation. From humans, embryonated eggs, called oncospheres, are released with faeces and are transmitted to cattle through contaminated fodder. Oncospheres develop inside muscle, liver, and lungs of cattle into infective cysticerci.
Dipylidium caninum, also called the flea tapeworm, double-pored tapeworm, or cucumber tapeworm, is a cyclophyllid cestode that infects organisms afflicted with fleas and canine chewing lice, including dogs, cats, and sometimes human pet-owners, especially children.
Ancylostoma duodenale is a species of the roundworm genus Ancylostoma. It is a parasitic nematode worm and commonly known as the Old World hookworm. It lives in the small intestine of hosts such as humans, cats and dogs, where it is able to mate and mature. Ancylostoma duodenale and Necator americanus are the two human hookworm species that are normally discussed together as the cause of hookworm infection. They are dioecious. Ancylostoma duodenale is abundant throughout the world, including Southern Europe, North Africa, India, China, southeast Asia, some areas in the United States, the Caribbean, and South America.
Uncinaria stenocephala is a nematode that parasitizes dogs, cats, and foxes as well as humans. It is rare to find in cats in the United States. The common name is the northern hookworm of dogs.
The Strongylida suborder includes many of the important nematodes found in the gastrointestinal tracts of ruminants, horses, and swine, as well as the lungworms of ruminants and the hookworms of dogs and cats.
Toxocara canis is worldwide-distributed helminth parasite of dogs and other canids. Toxocara canis is gonochoristic, adult worms measure from 9 to 18 cm, are yellow-white in color, and occur in the intestine of the definitive host. In adult dogs, the infection is usually asymptomatic. By contrast, massive infection with Toxocara canis can be fatal in puppies.
Gyrinicola batrachiensis are nematode parasites that are members of the order Oxyurida. Members of this order are also known as pinworms. These organisms are nematodes that feed on micro-particles in the gut of vertebrates and invertebrates. Oxyurida is further separated into two superfamilies: Oxyuroidea and Thelastomatoidea, which are parasites of vertebrates and invertebrates respectively. Oxyuroidea is composed on three families: Pharyngodonidae; parasites of herbivorous vertebrates, and Oxyuridae and Heteroxynematidae; parasites of mammals and some birds.
Toxascaris leonina is a common parasitic roundworm found in dogs, cats, foxes, and related host species. Toxascaris leonina, or T. leonina, is an ascarid nematode, a worldwide distributed helminth parasite which is in a division of eukaryotic parasites that, unlike external parasites such as lice and fleas, live inside their host. The definitive hosts of T. leonina include canids and felines (cats), while the intermediate hosts are usually rodents, such as mice or rats. Infection occurs in the definitive host when the animal eats an infected rodent. While T. leonina can occur in either dogs or cats, it is far more frequent in cats.
Hymenolepis microstoma, also known as the rodent tapeworm, is an intestinal dwelling parasite. Adult worms live in the bile duct and small intestines of mice and rats, and larvae metamorphose in the haemocoel of beetles. It belongs to the genus Hymenolepis; tapeworms that cause hymenolepiasis. H. microstoma is prevalent in rodents worldwide, but rarely infects humans.
Taenia serialis, also known as a canid tapeworm, is found within canines such as foxes and dogs. Adult T. serialis are parasites of carnivores, particularly dogs, with herbivorous lagomorph mammals such as rabbits and hares, serving as intermediate hosts. In definitive hosts, T. serialis is acquired by eating tissues from a variety of intermediate hosts. Accidental infection of humans though, can occur when eggs are ingested from food or water contaminated with dog feces and the human then becomes the T. serialis intermediate host.
Entovalva nhatrangensis is a species of small marine bivalve mollusc in the family Lasaeidae. It was first described in 2010 and its specific name "nhatrangensis" derives from the locality where it was originally found, Nha Trang Bay in Vietnam. It lives inside the oesophagus of certain species of sea cucumbers. It is considered to be an endosymbiont rather than a parasite because it does not harm its host.
Paragordius varius, also known as the nematomorphs or horsehair worm, are known to control their definitive host to jump into a pool of water, thus allowing the adult worm to escape and reproduce. They are similar to nematodes but are much longer and very thin. P. varius is usually found in water or wet areas. These worms definitive hosts consist of grasshoppers, crickets, cockroaches, and some beetles.
Parascaris equorum is a species of ascarid that is the equine roundworm. Amongst horse owners, the parasites are colloquially called "Ascarids". This is a host-specific helminth intestinal parasite that can infect horses, donkeys, and zebras. Horses up to six months of age are the most susceptible to infection. After this time, infection rates begin to decline and is extremely uncommon in horses over twelve months of age. It cannot infect humans or other animals. It is yellow-white in color, and females can become as large as 15 inches (38 cm) in length. Found worldwide, P. equorum is one of the most difficult equine parasites to kill, requiring larger doses of more powerful anthelmintic medications than are needed for other equine parasites.
Corynosoma autrale is a species of acanthocephalan. This species usually infects pinnipeds; the semi-aquatic fin-footed marine mammals most commonly known as seals and sea lions. Pinniped infections are not exclusive, recently C. australe has been discovered in Magellanic penguins.
Thyonicola dogieli is a parasitic species of gastropod mollusc in the family Eulimidae. It parasitises sea cucumbers in the northeastern Pacific Ocean.
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