Aquatic insects or water insects live some portion of their
life cycle in the water. They feed in the same ways as other
insect
Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...
s. Some ''diving'' insects, such as
predatory diving beetle
The Dytiscidae, from the Ancient Greek word δυτικός (''dystikos''), meaning "able to dive", are the predaceous diving beetles, a Family (biology), family of water beetles. They occur in virtually any freshwater habitat around the world, bu ...
s, can hunt for food underwater where land-living insects cannot
compete.
Breathing
One problem that aquatic insects must overcome is how to get
oxygen
Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...
while they are under water.
Almost all animals require a source of oxygen to live. Insects draw air into their bodies through
spiracles, holes found along the sides of the
abdomen
The abdomen (colloquially called the gut, belly, tummy, midriff, tucky, or stomach) is the front part of the torso between the thorax (chest) and pelvis in humans and in other vertebrates. The area occupied by the abdomen is called the abdominal ...
. 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
# Simple diffusion over a relatively thin
integument
# Temporary use of an air bubble
# Extraction of oxygen from water using a
plastron or
blood gill
# Storage of oxygen in
hemoglobin
Hemoglobin (haemoglobin, Hb or Hgb) is a protein containing iron that facilitates the transportation of oxygen in red blood cells. Almost all vertebrates contain hemoglobin, with the sole exception of the fish family Channichthyidae. Hemoglobin ...
and
hemocyanin molecules in
hemolymph
# Taking oxygen from surface via breathing tubes (
siphons)
The nymphs of the
hemimetabolous orders mayflies, dragonflies and stoneflies, and the larvae of the
holometabolous orders
megalopterans and caddisflies, possess tracheal gills, which are outgrowths of the body wall containing a dense network of tracheae covered by a thin cuticle through which oxygen in the water can diffuse.
Some insects have densely packed hairs (
setae) around the spiracles that allow air to remain near, while keeping water away from, the body. The trachea open through spiracles into this air film, allowing access to oxygen. In many such cases, when the insect dives into the water, it carries a layer of air over parts of its surface, and breathes using this trapped air bubble until it is depleted, then returns to the surface to repeat the process. Other types of insects have a
plastron or physical gill 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. In these insects, the volume of the film is small enough, and their respiration slow enough, that
diffusion
Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in Gibbs free energy or chemical p ...
from the surrounding water is enough to replenish the oxygen in the pocket of air as fast as it is used. The large proportion of
nitrogen
Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...
in the air dissolves in water slowly and maintains the gas volume, supporting oxygen diffusion. Insects of this type only rarely need to replenish their supply of air.
Other aquatic insects can remain under water for long periods due to high concentrations of hemoglobin in their hemolymph circulating freely within their body. Hemoglobin bonds strongly to oxygen molecules.
A few insects such as
water scorpions and
mosquito larvae have breathing tubes ("siphons") with the opening surrounded by
hydrofuge hairs, allowing them to breathe without having to leave the water.
Orders with aquatic or semiaquatic species
*Collembola -
springtail
Springtails (class Collembola) form the largest of the three lineages of modern Hexapoda, hexapods that are no longer considered insects. Although the three lineages are sometimes grouped together in a class called Entognatha because they have in ...
s (which are not technically insects, but are closely related)
*Ephemeroptera -
mayflies
*
Odonata -
dragonflies and
damselflies
*
Plecoptera
Plecoptera is an order (biology), order of insects commonly known as stoneflies. Some 3,500 species are described worldwide, with new species still being discovered. Stoneflies are found worldwide, except Antarctica. Stoneflies are believed to b ...
- stoneflies
*
Megaloptera -
alderflies,
fishflies, and
dobsonflies
*
Neuroptera - lacewings
*Coleoptera -
beetle
Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...
s
*
Hemiptera
Hemiptera (; ) is an order of insects, commonly called true bugs, comprising more than 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, bed bugs, and shield bugs. They range in size from ...
- true bugs (
water striders,
giant water bugs)
*
Hymenoptera -
ant
Ants are Eusociality, eusocial insects of the Family (biology), family Formicidae and, along with the related wasps and bees, belong to the Taxonomy (biology), order Hymenoptera. Ants evolved from Vespoidea, vespoid wasp ancestors in the Cre ...
s (e.g. ''
Polyrhachis sokolova'') and
wasp
A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder ...
s (e.g. ''
Microgaster godzilla'')
*Diptera -
flies
Flies are insects of the Order (biology), order Diptera, the name being derived from the Ancient Greek, Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwin ...
*
Mecoptera - scorpionflies
*
Lepidoptera
Lepidoptera ( ) or lepidopterans is an order (biology), order of winged insects which includes butterflies and moths. About 180,000 species of the Lepidoptera have been described, representing 10% of the total described species of living organ ...
-
moth
Moths are a group of insects that includes all members of the order Lepidoptera that are not Butterfly, butterflies. They were previously classified as suborder Heterocera, but the group is Paraphyly, paraphyletic with respect to butterflies (s ...
s
*Trichoptera -
caddisflies
EPT insects, an
acronym
An acronym is a type of abbreviation consisting of a phrase whose only pronounced elements are the initial letters or initial sounds of words inside that phrase. Acronyms are often spelled with the initial Letter (alphabet), letter of each wor ...
for Ephemeroptera, Plecoptera and Trichoptera (mayflies, stoneflies and caddisflies), are sensitive to pollutants and are used as an indicator of water quality in streams, rivers and lakes.
Marine aquatic insects
Aquatic insects live mostly in
freshwater habitats, and there are very few marine insect species. The only true examples of
pelagic insects are the
sea skaters, which belongs to the order Hemiptera, and there are a few types of insects that live in the
intertidal zone, including larvae of
caddisflies from the family
Chathamiidae,
the hemipteran ''
Aepophilus bonnairei'',
and a few other taxa.
References
* Farb, P. (1962). The Water Dwellers
IFENSECTS pg. 142.
* Meyer, J.R. (2006),
Respiration in Aquatic Insects. (Accessed 25 April 2008)
* Wigglesworth, Vincent B. Sir (1964). The life of insects. Weidenfeld & Nicolson, London
External links
- "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.''
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