Aquatic insects
Encyclopedia
Aquatic insects live some portion of their life cycle
in the water. They feed in the same ways as other insect
s. Some diving insects, such as predatory
diving beetles, can hunt for food underwater where land-living insects cannot compete
.
to live. Insects draw air into their bodies through spiracles, holes found along the sides of the abdomen
. These spiracles are connected to tracheal
tubes where oxygen can be absorbed. All aquatic insects have become adapted to their environment with the specialization of these structures.
Aquatic adaptations
Some insects have densely packed hairs (setae) around the spiracles that allow air to remain near, while keeping water away from, the body. They may even carry a bubble of air down from the surface. Others have a plastron that can be various combinations of hairs, scales, and undulations projecting from the cuticle, which hold a thin layer of air along the outer surface of the body. The trachea open through spiracles into this air film, allowing access to oxygen. The larvae and nymphs of mayflies, dragonflies and stoneflies still retain the air tubes they need for adult stage but when in larval stage they are equipped with gills that strain out oxygen in the water.
One mechanism used by some aquatic insects is one or more pockets of air called physical gills or sometimes 'gas gills'. When the insect dives into the water, it carries a layer of air over parts of its surface. The insect absorbs oxygen from this air as it would above the surface. Diffusion
from the surrounding water replenishes the oxygen in the pocket of air. The large proportion of nitrogen
in the air dissolves in water slowly and maintains the gas gill volume supporting oxygen diffusion. Insects need to periodically replenish their supply of air, not just oxygen.
Other aquatic insects can remain under water for long periods due to high concentrations of hemoglobin in their hemolymph circulating freely within the their body. Hemoglobin bonds strongly to oxygen molecules.
Biological life cycle
A life cycle is a period involving all different generations of a species succeeding each other through means of reproduction, whether through asexual reproduction or sexual reproduction...
in the water. They feed in the same ways as other insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s. Some diving insects, such as predatory
Predation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...
diving beetles, can hunt for food underwater where land-living insects cannot compete
Competition
Competition is a contest between individuals, groups, animals, etc. for territory, a niche, or a location of resources. It arises whenever two and only two strive for a goal which cannot be shared. Competition occurs naturally between living organisms which co-exist in the same environment. For...
.
Breathing
One problem that aquatic insects must overcome is how to get oxygen while they are under water. All animals require a source of oxygenOxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
to live. Insects draw air into their bodies through spiracles, holes found along the sides of the abdomen
Abdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...
. These spiracles are connected to tracheal
Invertebrate trachea
The invertebrate trachea refers to the open respiratory system composed of spiracles, tracheae, and tracheoles that terrestrial arthropods have to transport metabolic gases to and from tissues....
tubes where oxygen can be absorbed. All aquatic insects have become adapted to their environment with the specialization of these structures.
Aquatic adaptations
- Simple diffusion over a relatively thin integument
- Breathing from a plastron or physical gillGillA gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...
- Extraction of oxygen from water using a plastron or physical gill
- Storage of oxygen in hemoglobinHemoglobinHemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of all vertebrates, with the exception of the fish family Channichthyidae, as well as the tissues of some invertebrates...
molecules in hemolymphHemolymphHemolymph, or haemolymph, is a fluid in the circulatory system of some arthropods and is analogous to the fluids and cells making up both blood and interstitial fluid in vertebrates such as birds and mammals... - Taking oxygen from surface via breathing tubes (siphons)
Some insects have densely packed hairs (setae) around the spiracles that allow air to remain near, while keeping water away from, the body. They may even carry a bubble of air down from the surface. Others have a plastron that can be various combinations of hairs, scales, and undulations projecting from the cuticle, which hold a thin layer of air along the outer surface of the body. The trachea open through spiracles into this air film, allowing access to oxygen. The larvae and nymphs of mayflies, dragonflies and stoneflies still retain the air tubes they need for adult stage but when in larval stage they are equipped with gills that strain out oxygen in the water.
One mechanism used by some aquatic insects is one or more pockets of air called physical gills or sometimes 'gas gills'. When the insect dives into the water, it carries a layer of air over parts of its surface. The insect absorbs oxygen from this air as it would above the surface. Diffusion
Diffusion
Molecular diffusion, often called simply diffusion, is the thermal motion of all particles at temperatures above absolute zero. The rate of this movement is a function of temperature, viscosity of the fluid and the size of the particles...
from the surrounding water replenishes the oxygen in the pocket of air. The large proportion of nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
in the air dissolves in water slowly and maintains the gas gill volume supporting oxygen diffusion. Insects need to periodically replenish their supply of air, not just oxygen.
Other aquatic insects can remain under water for long periods due to high concentrations of hemoglobin in their hemolymph circulating freely within the their body. Hemoglobin bonds strongly to oxygen molecules.
Orders with aquatic or semi-aquatic species
- Collembola - springtailSpringtailSpringtails form the largest of the three lineages of modern hexapods that are no longer considered insects...
s (which are not technically insects, but are closely related) - Ephemeroptera - mayfliesMayflyMayflies are insects which belong to the Order Ephemeroptera . They have been placed into an ancient group of insects termed the Palaeoptera, which also contains dragonflies and damselflies...
- OdonataOdonataOdonata is an order of insects, encompassing dragonflies and damselflies . The word dragonfly is also sometimes used to refer to all Odonata, but the back-formation odonate is a more correct English name for the group as a whole...
- dragonfliesDragonflyA dragonfly is a winged insect belonging to the order Odonata, the suborder Epiprocta or, in the strict sense, the infraorder Anisoptera . It is characterized by large multifaceted eyes, two pairs of strong transparent wings, and an elongated body...
and damselfliesDamselflyDamselflies are insects in the order Odonata. Damselflies are similar to dragonflies, but the adults can be distinguished by the fact that the wings of most damselflies are held along, and parallel to, the body when at rest... - Plecoptera - stoneflies
- Hemiptera - true bugsHemipteraHemiptera is an order of insects most often known as the true bugs , comprising around 50,000–80,000 species of cicadas, aphids, planthoppers, leafhoppers, shield bugs, and others...
- MegalopteraMegalopteraMegaloptera is an order of insects. It contains the alderflies, dobsonflies and fishflies, and there are about 300 known species.The Megaloptera were formerly considered part of a group then called Neuroptera, together with lacewings and snakeflies, but these are now generally considered to be...
- alderfliesAlderflyAlderflies are megalopteran insects of the family Sialidae. They are closely related to the dobsonflies and fishflies as well as to the prehistoric Euchauliodidae. All living alderflies - about 66 species altogether - are part of the subfamily Sialinae, which contains between one and seven extant...
, fishfliesFishflyFishflies are the members of the subfamily Chauliodinae, belonging to the megalopteran family Corydalidae. They are most easily distinguished from their closest relatives, dobsonflies, by the jaws and antennae...
, and dobsonfliesDobsonflyA Dobsonfly is any insect of the subfamily Corydalinae, part of the megalopteran family Corydalidae. There are over 220 species of dobsonflies. Dobsonflies are found throughout the Americas and Asia, as well as South Africa... - NeuropteraNeuropteraThe insect order Neuroptera, or net-winged insects, includes the lacewings, mantidflies, antlions, and their relatives. The order contains some 6,010 species...
- lacewings - Coleoptera - beetleBeetleColeoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
s Beetles of the genus HelichusHelichusBeetles of the genus Helichus are found worldwide apart from in Australia and Antarctica. Adults reach long and live in aquatic or riparian environments. The larvae are land-dwelling which may be unique in water living insects....
are the only insects known where the larvae are land-based and the adults live in water. - HymenopteraHymenopteraHymenoptera is one of the largest orders of insects, comprising the sawflies, wasps, bees and ants. There are over 130,000 recognized species, with many more remaining to be described. The name refers to the heavy wings of the insects, and is derived from the Ancient Greek ὑμήν : membrane and...
- antAntAnts are social insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the mid-Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants. More than...
s (e.g. Polyrhachis sokolovaPolyrhachis sokolovaPolyrhachis sokolova is a species of ant recently discovered to be capable of surviving tidal inundations.Researchers at the James Cook University gained attention in 2006 after finding and reporting this behavior. Polyrhachis sokolova nests in mud in mangrove swamps, regularly inundated by rising...
) and waspWaspThe term wasp is typically defined as any insect of the order Hymenoptera and suborder Apocrita that is neither a bee nor an ant. Almost every pest insect species has at least one wasp species that preys upon it or parasitizes it, making wasps critically important in natural control of their...
s - Diptera - fliesFlyTrue flies are insects of the order Diptera . They possess a pair of wings on the mesothorax and a pair of halteres, derived from the hind wings, on the metathorax...
- Mecoptera - scorpionflies
- LepidopteraLepidopteraLepidoptera is a large order of insects that includes moths and butterflies . It is one of the most widespread and widely recognizable insect orders in the world, encompassing moths and the three superfamilies of butterflies, skipper butterflies, and moth-butterflies...
- mothMothA moth is an insect closely related to the butterfly, both being of the order Lepidoptera. Moths form the majority of this order; there are thought to be 150,000 to 250,000 different species of moth , with thousands of species yet to be described...
s - Trichoptera - caddisflies
External links
- Insect stages - "Some larvae, nymphs and adult insects that live in freshwater." A UK-based web site with microscopic photos of various insects and other microorganisms as well as biological information.
- Aquatic Insects article by Jeff Shearer