Gerris lacustris
Encyclopedia
Gerris lacustris, commonly known as the common pond skater or common water strider, is a species
of water strider, found across Europe
.
; the first pair is short and stubby while the other two pairs are thin and elongated which are used for moving over the water surface which we call "walking on water". The first pair of legs is used for holding its prey, the middle pair propels the bug along the surface of the water with either a rowing
or jumping motion, and the hind pair of legs is used as rudder
s. The entire body of G. lacustris including its legs is covered with many tiny hairs that have a wax-like coating. G. lacustris are dark brown in colour. Water striders have very strong sucking mouthparts
known as a rostrum
or beak.
and the egg
production rate is limited by the amount of food resources that are available to the female; the more food there is the more eggs the female lays. The adult water striders emerge around April and May. It is around this time that females lay eggs where the eggs undergo a process that takes about 12 to 14 days to develop before they are able to hatch. Hatching doesn't necessarily follow the eggs when their development is complete; hatching heavily depends on the temperature
that the egg is exposed to in its environment. After hatching, G. lacustris go through another separate development process known as incomplete metamorphosis. In this process, the larva
e or nymphs
progress through a series of moults
which basically are stages known as instar
s. There are five instars in the developmental process, with each one progressively longer than the last. The incomplete metamorphosis process usually lasts about 24 to 30 days for larvae to become an adult. G. lacutris males prolong their mating in the presence of other males because they are guarding their female against harassment from the other males. It was found that males influence the duration of copulation while the females influence the copulation frequency.
by paddling forward with the middle pair of legs while the forelegs and hind legs act as a rudder. Waters striders also have the ability to stand effortlessly on water due to their non-wetting legs. Because they have tiny hairs with nanogrooves that cover their bodies, they have a water resistance
effect. Water striders rely on surface tension
to walk on top of water. Through evolution, water striders have developed a unique arrangement of legs which gives them the gliding ability with greatly elongated med-legs. The Hox gene "ultrabithorax
" lengthens legs in insects. If its pool should dry out during a drought
, a water strider will travel overland to find wetter pastures to settle in.
The front pair of legs of a water strider do not act as a rudder - they are very short and are held up in the air, ready to grab prey. They also do not feel the vibrations in the water of prey -- the middle and hind pair of legs do this.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of water strider, found across Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
.
Physical description
Water striders vary in length ranging between 8 millimetre (0.31496062992126 in) and 10 mm (0.393700787401575 in) in size. Their body shape is very slender and elongated. They have six legsArthropod leg
The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments are of Latin origin, and may be confused with terms for bones: coxa , trochanter , femur, tibia, tarsus, ischium, metatarsus, carpus, dactylus ,...
; the first pair is short and stubby while the other two pairs are thin and elongated which are used for moving over the water surface which we call "walking on water". The first pair of legs is used for holding its prey, the middle pair propels the bug along the surface of the water with either a rowing
Watercraft rowing
Watercraft rowing is the act of propelling a boat using the motion of oars in the water. The difference between paddling and rowing is that with rowing the oars have a mechanical connection with the boat whereas with paddling the paddles are hand-held with no mechanical connection.This article...
or jumping motion, and the hind pair of legs is used as rudder
Rudder
A rudder is a device used to steer a ship, boat, submarine, hovercraft, aircraft or other conveyance that moves through a medium . On an aircraft the rudder is used primarily to counter adverse yaw and p-factor and is not the primary control used to turn the airplane...
s. The entire body of G. lacustris including its legs is covered with many tiny hairs that have a wax-like coating. G. lacustris are dark brown in colour. Water striders have very strong sucking mouthparts
Insect mouthparts
Insects exhibit a range of mouthparts, adapted to particular modes of feeding. The earliest insects had chewing mouthparts...
known as a rostrum
Rostrum (anatomy)
The term rostrum is used for a number of unrelated structures in different groups of animals:*In crustaceans, the rostrum is the forward extension of the carapace in front of the eyes....
or beak.
Reproduction
G. lacustris females are usually significantly larger than the malesSexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...
and the egg
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
production rate is limited by the amount of food resources that are available to the female; the more food there is the more eggs the female lays. The adult water striders emerge around April and May. It is around this time that females lay eggs where the eggs undergo a process that takes about 12 to 14 days to develop before they are able to hatch. Hatching doesn't necessarily follow the eggs when their development is complete; hatching heavily depends on the temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
that the egg is exposed to in its environment. After hatching, G. lacustris go through another separate development process known as incomplete metamorphosis. In this process, the larva
Larva
A larva 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 or nymphs
Nymph (biology)
In biology, a nymph is the immature form of some invertebrates, particularly insects, which undergoes gradual metamorphosis before reaching its adult stage. Unlike a typical larva, a nymph's overall form already resembles that of the adult. In addition, while a nymph moults it never enters a...
progress through a series of moults
Ecdysis
Ecdysis is the moulting of the cuticula in many invertebrates. This process of moulting is the defining feature of the clade Ecdysozoa, comprising the arthropods, nematodes, velvet worms, horsehair worms, rotifers, tardigrades and Cephalorhyncha...
which basically are stages known as instar
Instar
An instar is a developmental stage of arthropods, such as insects, between each molt , until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, or...
s. There are five instars in the developmental process, with each one progressively longer than the last. The incomplete metamorphosis process usually lasts about 24 to 30 days for larvae to become an adult. G. lacutris males prolong their mating in the presence of other males because they are guarding their female against harassment from the other males. It was found that males influence the duration of copulation while the females influence the copulation frequency.
Food and nutrients
G. lacustris is a predatory insect. The species hunts on or below water surface for insects and other small invertebrates using their strong forelegs which end with claws. They also have piercing and sucking mouthparts in order to consume other small insects that fall into the water surface and to feed on live and dead insects such as culiseta annulata, non-biting midge, and other water invertebrates. With their front pair of legs they’re able to detect ripples and sense vibrations in the surface film from struggling insects and handle or grasp their prey. G. lacustris eat other small invertebrates and digest them internally.Adaptations
Water striders have the ability to move quickly on the water surface and have hydrophobic legs. On average, a water strider can move 1.5 metre per secondMetre per second
Metre per second is an SI derived unit of both speed and velocity , defined by distance in metres divided by time in seconds....
by paddling forward with the middle pair of legs while the forelegs and hind legs act as a rudder. Waters striders also have the ability to stand effortlessly on water due to their non-wetting legs. Because they have tiny hairs with nanogrooves that cover their bodies, they have a water resistance
Water resistance
Water resistance may refer to:* wet strength, a measure of how well a fibreweb is holds together upon a force of rupture* waterproofing, making objects relatively unaffected by water or resisting the ingress of water under specified conditions...
effect. Water striders rely on surface tension
Surface tension
Surface tension is a property of the surface of a liquid that allows it to resist an external force. It is revealed, for example, in floating of some objects on the surface of water, even though they are denser than water, and in the ability of some insects to run on the water surface...
to walk on top of water. Through evolution, water striders have developed a unique arrangement of legs which gives them the gliding ability with greatly elongated med-legs. The Hox gene "ultrabithorax
Ultrabithorax
Ultrabithorax or Ubx is a member of the homeobox gene family. Homeobox proteins function as transcription factors. In Drosophila melanogaster it is expressed in the third thoracic and first abdominal segments and represses wing formation. The Ubx gene regulates the decisions regarding the...
" lengthens legs in insects. If its pool should dry out during a drought
Drought
A drought is an extended period of months or years when a region notes a deficiency in its water supply. Generally, this occurs when a region receives consistently below average precipitation. It can have a substantial impact on the ecosystem and agriculture of the affected region...
, a water strider will travel overland to find wetter pastures to settle in.
The front pair of legs of a water strider do not act as a rudder - they are very short and are held up in the air, ready to grab prey. They also do not feel the vibrations in the water of prey -- the middle and hind pair of legs do this.