Nematomorpha

Nematomorpha is a phylum of worms whose larvae parasitize arthropods, while adults live freely in water or moist habitats. Its members are commonly called horsehair worms or Gordian worms.

Parasitism: A biological interaction in which one organism lives on or in another and gains resources at its expense. Nematomorph larvae develop inside living arthropods, using them as hosts.
Arthropoda: A phylum of invertebrates characterized by jointed appendages, segmented bodies, and an external skeleton. Arthropods, especially insects, serve as hosts for nematomorph larvae.
Freshwater ecology: The study of interactions among organisms and their physical environment in freshwater systems. Adult worms and emerging parasites connect terrestrial hosts to aquatic habitats.
Paragordius tricuspidatus: A horsehair worm species known to develop in terrestrial crickets and emerge in water. Its infection of crickets is a well-studied example of host manipulation.
Host manipulation: A parasite-induced change in a host's behavior that benefits the parasite. Mature worms can induce infected terrestrial arthropods to enter water, where the worms emerge.
Nematoda: A phylum of unsegmented, cylindrical worms with a tough external cuticle. Nematomorphs resemble nematodes in shape but belong to a distinct phylum.
Biological control: The use of living organisms to suppress populations of pests or other unwanted organisms. Their effects on arthropod hosts have prompted interest in their potential to limit pest populations.
Spinochordodes tellinii: A horsehair worm species whose larvae develop in terrestrial insects, including grasshoppers and crickets. This species is associated with infected insects entering water before adult emergence.
Parasitic castration: A parasite's suppression of its host's reproduction through damage or physiological manipulation. Nematomorph infection can redirect host resources away from reproduction.
Cuticle: A noncellular outer layer secreted by an animal's epidermis. A cuticle covers the nematomorph body and is shed during development.

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