The Hydropsychidae are a

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

-level taxon consisting of net-spinning

caddisflies The caddisflies, or order Trichoptera, are a group of insects with aquatic larvae and terrestrial adults. There are approximately 14,500 described species, most of which can be divided into the suborders Integripalpia and Annulipalpia on the ...

. Hydropsychids are common among much of the world's streams, and a few species occupy the shorelines of freshwater lakes.

Larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

e of the hydropsychids construct nets at the open ends of their dwellings which are responsible for their "net-spinning caddisfly"

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...

Larvae

The hydropsychid

larval A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

stage, like most

Trichoptera The caddisflies, or order Trichoptera, are a group of insects with aquatic larvae and terrestrial adults. There are approximately 14,500 described species, most of which can be divided into the suborders Integripalpia and Annulipalpia on the b ...

larvae, is spent entirely in

fresh water Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does incl ...

. They construct dwellings known as "retreats", which are fixed to the sides of rocks. These retreats are typically composed of collected plant and mineral fragments. At the large open end of their retreats, hydropsychids spin a net or

sieve A sieve, fine mesh strainer, or sift, is a device for separating wanted elements from unwanted material or for controlling the particle size distribution of a sample, using a screen such as a woven mesh or net or perforated sheet materia ...

made of fine silk, similar to the silk produced by the larval form of the

Lepidoptera Lepidoptera ( ) is an order of insects that includes butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 families and 46 superfamilies, 10 percent of the total described speci ...

(

caterpillars Caterpillars ( ) are the larval stage of members of the order Lepidoptera (the insect order comprising butterflies and moths). As with most common names, the application of the word is arbitrary, since the larvae of sawflies (suborder Symp ...

), one of their close relatives. These nets catch

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular micr ...

detritus In biology, detritus () is dead particulate organic material, as distinguished from dissolved organic material. Detritus typically includes the bodies or fragments of bodies of dead organisms, and fecal material. Detritus typically hosts comm ...

, and smaller

invertebrates Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordat ...

. Different

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

spin nets of different mesh sizes and shapes depending on what food type they are targeting. Because of this technique of food collection, hydropsychids require flowing water to ensnare items of food into their nets. Hydropsychids are capable of performing a defensive

stridulation Stridulation is the act of producing sound by rubbing together certain body parts. This behavior is mostly associated with insects, but other animals are known to do this as well, such as a number of species of fish, snakes and spiders. The mech ...

in their larval stages. Individuals stridulate to dissuade other hydropsychids from attempts to steal their retreats. When individuals abandon, or become dislodged from, their retreats, they must build or seize a new retreat. "Home-less" hydropsychids will sometimes search out retreats currently occupied by another member of their

species 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 appropriat ...

. This can result in a confrontation between individuals, each vying for ownership of an established retreat. Stridulating warns foes that a retreat is occupied and attempting to enter is unwise. This noise is made by running their

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates ...

s across ridges on the undersides of their heads. It is still unclear whether this noise is also used to dissuade

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pa ...

predators.

Anatomy

Hydropsychid

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

e are unique from most

due to their fully scleritized dorsum. Only the

Hydroptilidae The Hydroptilidae are a large family of caddisflies (Trichoptera) with a worldwide distribution. They are commonly known as microcaddisflies or purse-case caddisflies, in reference to two characteristic traits of this family: Hydroptilidae are ...

family share this characteristic with the hydropsychids. This feature combined with branched

gills A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

running along

ventral Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

surface of their

abdomen The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the to ...

s differentiate the hydropsychids from all other trichopterans. The hydropsychids have large anal

proleg A proleg is a small, fleshy, stub structure found on the ventral surface of the abdomen of most larval forms of insects of the order Lepidoptera, though they can also be found on other larval insects such as sawflies and a few other types of in ...

s equipped with hooks, allowing them to grasp the side of rocks in river and stream beds. Individuals are easily identified without the use of a lens by their large, curved bodies. In India four subfamilies (Arctopsychinae, Martynov 1924, Diplectroninae, Ulmer 1951, Hydropsychinae, Curtis 1835, Macronematinae, Ulmer 1905) have been reported so far which includes 15 genera and 128 species.

Environmental indicators

Due to hydropsychid's presence in a wide range of rivers and streams worldwide, it has been favored as an

indicator species A bioindicator is any species (an indicator species) or group of species whose function, population, or status can reveal the qualitative status of the environment. The most common indicator species are animals. For example, copepods and other sm ...

. Some genera, sensitive to certain contaminants or

pollutants A pollutant or novel entity is a substance or energy introduced into the environment that has undesired effects, or adversely affects the usefulness of a resource. These can be both naturally forming (i.e. minerals or extracted compounds like o ...

, suffer declines in growth and/or survival. Thus, like a

canary Canary originally referred to the island of Gran Canaria on the west coast of Africa, and the group of surrounding islands (the Canary Islands). It may also refer to: Animals Birds * Canaries, birds in the genera '' Serinus'' and ''Crithagra'' ...

in a coal mine, researchers can examine stream hydropsychid populations to assess stream health (see EPT or

Index of biological integrity An index of biological integrity (IBI), also called an index of biotic integrity, is a scientific tool typically used to identify and classify water pollution problems, although there have been some efforts to apply the idea to terrestrial environme ...

References

{{Taxonbar, from=Q1949522 Trichoptera families Taxa named by John Curtis