Nematomorpha

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Nematomorpha

Nematomorpha (sometimes called Gordiacea, and commonly known as Horsehair worms or Gordian worms) are a phylum

Phylum

A phylum "Phylum" is adopted from the Greek phylai, the clan-based voting groups in Greek city-states. is a taxonomic rank below Kingdom and above Class ....
of parasitic animal

Animal

Animals are a major group of multicellular, eukaryotic organisms of the Kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life....
s which are morphologically

Morphology (biology)

The term morphology in biology refers to form, structure and configuration of an organism. This includes aspects of the outward appearance as well as the form and structure of the internal parts like bones and organs....
and ecologically

Ecology

Ecology is the science study of the distribution and Abundance of life and the interactions between organisms and their nature environment ....
similar to nematode

Nematode

The "roundworms" or "nematodes" are the most diverse phylum of body cavity, and one of the most diverse of all animals. Nematode species are very difficult to distinguish; over 80,000 have been described, of which over 15,000 are parasite....
worms, hence the name. They range in size from 1cm to 1 meter long, and 1 to 3 millimetres in diameter. Horsehair worms can be discovered in damp areas such as watering troughs, streams, puddles, and cisterns.

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Encyclopedia

Nematomorpha (sometimes called Gordiacea, and commonly known as Horsehair worms or Gordian worms) are a phylum

Phylum

A phylum "Phylum" is adopted from the Greek phylai, the clan-based voting groups in Greek city-states. is a taxonomic rank below Kingdom and above Class ....
of parasitic animal

Animal

Morphology (biology)

Ecology

Ecology is the science study of the distribution and Abundance of life and the interactions between organisms and their nature environment ....
similar to nematode

Nematode

Larva

A larva is a young form of animal with indirect developmental biology, going through or undergoing metamorphosis .The larva can look completely different from the adult form, for example, a caterpillar differs from a butterfly....
e are parasitic on beetle

Beetle

Beetles are the group of insects with the largest number of known species. They are placed in the order Coleoptera , which contains more described species than in any other order in the animal, constituting about 25% of all known life-forms....
s, cockroach

Cockroach

Cockroaches are insects of the order Blattaria. This name derives from the Latin word for "cockroach", blatta.There are about 4,000 species of cockroach, of which 30 species are associated with human habitations and about four species are well known as pest s....
es, grasshopper

Grasshopper

Grasshoppers are insects of the suborder Caelifera in the order Orthoptera. To distinguish them from Tettigoniidae, they are sometimes referred to as short-horned grasshoppers....
s and crustacean

Crustacean

Crustaceans are a large group of arthropods, comprising almost 52,000 described species , and are usually treated as a subphylum . They include various familiar animals, such as crabs, lobsters, crayfish, shrimp, krill and barnacles....
s. About 326 species are known and a conservative estimate suggests that there may be about 2000 species worldwide. The name "Gordian" stems from the legendary Gordian knot

Gordian Knot

The Gordian Knot is a legend associated with Alexander the Great. It is often used as a metaphor for an intractable problem, solved by a bold stroke :...
. This relates to the fact the nematomorpha often tie themselves in knots.

Nematomorphs possess an external cuticle

Cuticle

In biology, a cuticle or cuticula is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or part of an organism, that provide protection....
without cilia. Internally, they have only longitudinal muscle and a non-functional gut, with no excretory

Excretory system

This system involves the kidneys and the liver which is not part of the system but creates most of the excreted waistLeifangThe excretory system excretes wastes....
, respiratory

Respiratory system

A respiratory system?s function is to allow gas exchange. The space between the alveoli and the capillaries, the anatomy or structure of the exchange system, and the precise physiological uses of the exchanged gases vary depending on the organism....
or circulatory system

Circulatory system

The circulatory system is an organ that moves nutrients, gases, and wastes to and from cells to help fight diseases and help stabilize body temperature and pH to maintain homeostasis....
s. Reproductively, they are dioecious

Dioecious

Dioecious - from Greek language for "two households" - refers to species of seed-bearing plants having separate male and female plants. That is, no individual plant of the species produces both microspores and megaspores; individual plants are either male or female ....
, with the internal fertilization of eggs that are then laid in gelatinous strings. The larvae that hatch have rings of cuticular hooks and terminal stylets that are believed to be used to enter the hosts. They are mostly free living but males and females aggregate into tight balls (Gordian knots) during mating.

Nematomorphs can be confused with nematodes, particularly Mermithid

Mermithidae

Mermithidae is a family of nematode worms that are endoparasites in arthropods. As early as 1877, Mermithidae was listed as one of nine subdivisions of the Nematoidea....
worms. Unlike Nematomorphs, Mermithids do not have a terminal cloaca

Cloaca

In zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the alimentary tract and urinary tract of certain animal species....
. Male mermithids have one or two spicules just before the end apart from having a thinner, smoother cuticle, without areoles and a paler brown colour.

In Spinochordodes tellinii
Spinochordodes tellinii

The Nematomorpha Spinochordodes tellinii is a parasitism worm whose larvae develop in Orthopteran insects . This parasite is able to influence its host's behavior: once the parasite is grown, it causes its grasshopper host to jump into water, where the grasshopper will likely drown....
, which has grasshoppers as its vector

Vector (biology)

In epidemiology, a vector is an organism that does not cause disease itself but that transmits infection by conveying pathogens from one Host to another, serving as a transmission ....
, the infection acts on the grasshopper's brain and causes it to seek water and drown itself, thus returning the nematomorph to water. They are also remarkably able to survive the predation of their host, being able to wriggle out of the predator which has eaten the host cricket.

The phylum is placed along with the Ecydosoa clade of moulting organisms that include the Arthropod

Arthropod

Arthropods are animals belonging to the Scientific classification Arthropoda , and include the insects, arachnids, crustaceans, and others....
a. Fossilized worms have been reported from Early Cretaceous Burmese amber dated to 100-110 million years apart from a fossil from the Mesozoic.

Relationships within the phylum are still somewhat unclear, but two classes are recognised:

Class Nectonematoida: Marine, planktonic, with a double row of natotory seta
Seta

Seta is a biology term derived from the Latin word for "bristle". It refers to a number of different bristle- or hair-like structures on living organisms....
e along each side of the body; with dorsal and ventral longitudinal epidermal cords, blastocoelom spacious and fluid filled; gonad
Gonad

The gonad is the organ that makes gametes. The gonads in males are the testes and the gonads in females are the ovaries. The product, gametes, are haploid germ cells....
s single; larvae parasitise decapod crustaceans
Decapoda

The decapods or Decapoda are an order of crustaceans within the class Malacostraca, including many familiar groups, such as crayfish, crabs, lobsters, prawns and shrimp....
Class Gordioidea: Freshwater and semiterrestrial; lack lateral rows of setae; with a single, ventral epidermal cord; blastocoelom filled with mesenchyme
Mesenchyme

Mesenchyme is a type of loose connective tissue, of mesodermal origin and located within the embryo mesoderm, consisting of a ground substance Matrix containing a loose aggregate of unspecialized cell which are capable of developing into connective tissue, bone, cartilage, the lymphatic system, and the circulatory system....
in young animals but becomes spacious in older individuals; larvae parasitise grasshoppers and cricket
Cricket

Cricket is a Bat-and-ball games team sport that originated in southern England. The earliest definite reference is dated 1598, and it is now played in more than 100 countries....
s

External links

with the worm emerging to mate, as well as emerging from predators which have eaten the infected cricket. From Nature
Nature (journal)

Nature is a prominent scientific journal, first published on 4 November 1869. Although most scientific journals are now highly specialized, Nature is one of the few journals, along with other weekly journals such as Science and Proceedings of the National Academy of Sciences, that still publishes original research articles ac...
, April 2006.
on the UF
University of Florida

The University of Florida is a Public university land-grant university, sea grant colleges, Space grant colleges major research university located on a campus in Gainesville, Florida, in the United States....
/ IFAS
Institute of Food and Agricultural Sciences

The University of Florida?s Institute of Food and Agricultural Sciences is a federal-state-county partnership dedicated to developing knowledge in agriculture, human and natural resources, and the life sciences, and enhancing and sustaining the quality of human life by making that information accessible....
Featured Creatures Web site