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 pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs ...
s. Some ''diving'' insects, such as
predatory diving beetle
The Dytiscidae – based on the Greek ''dytikos'' (δυτικός), "able to dive" – are the predaceous diving beetles, a family of water beetles. They occur in virtually any freshwater habitat around the world, but a few species live a ...
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 while they are under water.
Almost all animals require a source of
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as we ...
to live. Insects draw air into their bodies through
spiracles, holes found along the sides of the
abdomen
The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the tors ...
. 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
A blood gill is a gill like structure restricted to organs with spacious lumen and poorly developed/absent trachea, found in larvae of aquatic insects. Specific research questions the functionality of this gill to respiration
Respiration may ref ...
# Storage of oxygen in
hemoglobin
Hemoglobin (haemoglobin BrE) (from the Greek word αἷμα, ''haîma'' 'blood' + Latin ''globus'' 'ball, sphere' + ''-in'') (), abbreviated Hb or Hgb, is the iron-containing oxygen-transport metalloprotein present in red blood cells (erythrocyte ...
molecules in
hemolymph
# Taking oxygen from surface via breathing tubes (
siphons
A siphon (from grc, σίφων, síphōn, "pipe, tube", also spelled nonetymologically syphon) is any of a wide variety of devices that involve the flow of liquids through tubes. In a narrower sense, the word refers particularly to a tube in a ...
)
The larvae and nymphs of mayflies, dragonflies and stoneflies possess tracheae, but while in the larval or nymph stage the tracheae are connected to gills, which are very thin extensions of the exoskeleton 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 the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seve ...
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
Mosquitoes (or mosquitos) are members of a group of almost 3,600 species of small flies within the family Culicidae (from the Latin ''culex'' meaning " gnat"). The word "mosquito" (formed by ''mosca'' and diminutive ''-ito'') is Spanish for "l ...
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 -
springtails (which are not technically insects, but are closely related)
*Ephemeroptera -
mayflies
*
Odonata -
dragonflies and
damselflies
*Plecoptera -
stoneflies
*
Megaloptera -
alderflies
Alderflies 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 all together – are part of the subfa ...
,
fishflies, and
dobsonflies
*
Neuroptera -
lacewings
*Coleoptera -
beetle
Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...
s
*
Hemiptera - true bugs (
water striders,
giant water bugs
Belostomatidae is a family of freshwater hemipteran insects known as giant water bugs or colloquially as toe-biters, Indian toe-biters, electric-light bugs, alligator ticks, or alligator fleas (in Florida). They are the largest insects in the or ...
)
*
Hymenoptera -
ants (e.g. ''
Polyrhachis sokolova'') and
wasps (e.g.''
Microgaster godzilla
''Microgaster godzilla'' is a species of aquatic parasitoid wasp from Japan. Its host is the caterpillar '' Elophila turbata''. The wasp is named after Godzilla (1954 film)
is a 1954 Japanese ''kaiju'' film directed by Ishirō Honda, wi ...
'')
*
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 hindwing ...
and
mosquitoes
*Mecoptera -
scorpionflies
*
Lepidoptera -
moth
Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of ...
s
*Trichoptera -
caddisflies
EPT insects, an
acronym
An acronym is a word or name formed from the initial components of a longer name or phrase. Acronyms are usually formed from the initial letters of words, as in '' NATO'' (''North Atlantic Treaty Organization''), but sometimes use syllables, a ...
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 insect
The aquatic insects live mostly in
freshwater habitats since there are very few marine insect species.
Why are there so few insects at sea?
''Deutsche Welle'', 9 July 2018. The only true example of such insects are the sea skaters, which belongs to Hemiptera order.
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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