Hydropsychidae
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| Hydropsychidae | ||||||||||||||
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Arctopsychinae |
Hydropsychidae is a family level taxon consisting of net-spinning caddisflies. Hydropsychids are common among much of the wolrd's streams and a few species occupy the shorelines of freshwater lakes. Larvae of the hyrdopsychids construct nets at the open end of their dwellings which is reponsible for their "net-spinnig caddisfly" common name.
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[edit] Larvae
The Hydropsychid larval life-stage, like most Trichoptera larvae, is spent entirely in freshwater. 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 retreat, Hydropsychids spin a net or sieve made of fine silk, similar to the silk produced by the larval form of the Lepidoptera (caterpillars), one of their close relatives. These nets catch algae, detritus, and smaller invertebrates. Different genera spin nets of different mesh sizes and shape depending on what food type they are targeting.[1] Because of this technique of food collection, Hydropsychids require flowing water in order to ensnare items in their net.
When individuals abandon, or become dislodged from, their retreat, they must build or seize a new retreat. It has be shown that "home-less" Hyrdopsychids sometimes search out new retreats and even attempt to enter retreats still occupied by another member of their species.[2] This can result in a battle between individuals, each vying for ownership of the established retreat. Hydropsychids are very agile, able to maneuver in strong flowing water using their large anal prolegs to hold their position. Hydropsychids can stridulate to deter individuals from attempting to enter a battle with them.[2] This noise is made by running their femur across ridges on the underside of their head. It is still unclear whether this noise is also used to dissuade insect predators.
[edit] Anatomy
Hydropsychid larvae are unique from most Trichopteran due to their fully scleritized dorsum. Only the Hydroptilidae family share this characteristic with the Hydropsychids. This feature combined with branched gills running along ventral surface of the abdomen differeniate the Hydropsychid from all other Trichopteran.[3] The Hydropsychids have large anal prolegs 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.
[edit] Environmental Indicators
Due to Hydropsychid's presence in a wide range of rivers and streams world wide, it has been favored as a indicator species.[4][5] Some genera, sensitive to certain contaminants or pollutants, suffer declines in growth and/or survival. Like a canary in a coal mine, if there is a chemical that may be otherwise difficult to detect present in the Hydropsychid's stream water, a researcher may notice effects on Hydropsychid populations.
[edit] References
- ^ Wallace, JB (1975). "Food partitioning in net-spinning trichoptera larvae-Hydropsyche-Venularis, Cheumatopsyche-Etrona, and Maconema-Zebratum (Hydropsychidae)". Annals of Entomological Society of America 68 (3): 463–472.
- ^ a b Jansson, A; Vuoristo, T (1979). "Significance of stridulation in larval Hydropsychidae (Trichoptera)". Behaviour 71: 197–186.
- ^ Wiggins, Glenn (1996). Larvae of the North American Caddisfly Genera (Trichoptera) 2nd ed., 126. ISBN 0-8020-2723-7.
- ^ Stuijfzand, S.C. (1999). "Caddisflies (Trichoptera: Hydropsychidae) Used for Evaluating Water Quality of Large European Rivers". Archives of Environmental Contamination and Toxicology 36: 186–192. doi:.
- ^ Vuori, K.M.; Parkko, M. (1996). "Assessing pollution of the river Kymijoki via hydropsychid caddis flies". Archiv für Hydrobiologie 136 (2): 171–190.
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