Gerris

Fabricius, 1794

water striders

Species Guides

Gerris is a of water striders ( Gerridae) comprising 43 in three subgenera (Gerris, Gerriselloides, and Macrogerris). Species in this genus inhabit freshwater surfaces across temperate regions, where they use surface tension to walk on water. The genus has become a model system for studying sexual conflict, with well-documented antagonistic between males and females over mating control.

Gerris argenticollis by (c) Matthew Pintar, some rights reserved (CC BY), uploaded by Matthew Pintar. Used under a CC-BY license.

Gerris insperatus by (c) Matthew Pintar, some rights reserved (CC BY), uploaded by Matthew Pintar. Used under a CC-BY license.

Pronunciation

How to pronounce Gerris: //ˈdʒɛrɪs//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Gerris are distinguished from other gerrid by genitalic and structural characters; specific identification often requires examination of male genitalia. Former members of this genus have been reclassified to Aquarius, Limnoporus, and Emesa based on morphological revisions. Subgenus Macrogerris contains species with notably slender body forms and elongated relative to other subgenera.

Images

Habitat

Freshwater surface including ponds, lakes, slow-moving streams, and marshes. Specific microhabitat preferences vary by : Gerris lacustris occurs in small deep ponds or river banks with steep slopes, while Gerris occupies large marshes with low stagnant water and abundant vegetation. Species tolerate some degree of human habitat modification.

Distribution

Widespread in temperate regions of the Northern Hemisphere; documented from mountainous tributaries of the Vişeu River in Romania and across North America, Europe, and Asia. The contains 43 with distributions varying by subgenus.

Behavior

Males harass females persistently to achieve copulation, mounting females and tapping legs on the water surface to attract and force mating. Females resist through backward somersaulting movements, evasive maneuvers, and genital shielding (particularly in G. gracilicornis). Post-copulatory guarding occurs, with males remaining mounted on females; females may extend guarding duration to reduce harassment from additional males. Underwater basking has been observed: individuals voluntarily submerge to 5-30 cm depths and anchor to submerged vegetation during high temperatures, using a (air bubble held by hydrofuge hairs) for respiration while thermoregulating.

Human Relevance

Used as a model organism for studying sexual conflict and antagonistic due to measurable costs associated with mating . Laboratory studies on G. comatus, G. alacris, and G. buenoi have examined impacts for understanding - dynamics in aquatic systems.

Similar Taxa

AquariusFormerly classified within Gerris; distinguished by morphological revisions that led to reclassification of including G. ampla, G. conformis, G. najas, G. nebularis, G. nyctalis, and G. remigis.
LimnoporusFormerly classified within Gerris; reclassification based on structural characters separating G. canaliculatus, G. dissortis, and G. rufoscutellatus from true Gerris.
EmesaFormerly contained G. mantis, now reclassified as E. mantis based on morphological distinctions.

More Details

Subgeneric classification

The contains three subgenera: Gerris (type subgenus), Gerriselloides (containing G. asper, G. brachynotus, G. kiritshenkoi, G. lateralis), and Macrogerris (containing G. cui, G. gracilicornis, G. insularis, G. issikii, G. lundbladi, G. tigrinus, G. yezoensis).

Parasitism vulnerability

Gerris are vulnerable to by larval water mites (Limnochares aquatica, Acari: Hydrachnidia). Parasitism significantly increases mortality, extends instar duration, and increases variance in age at first moult. Effects are most severe during the first instar, with G. buenoi showing greater mortality than G. comatus or G. alacris under comparable mite loads.