Copepod
Encyclopedia
Copepods are a group of small crustacean
s found in the sea and nearly every freshwater
habitat
. Some species are plankton
ic (drifting in sea waters), some are benthic
(living on the ocean floor), and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests, bogs, springs, ephemeral ponds and puddles, damp moss, or water-filled recesses (phytotelmata
) of plants such as bromeliads and pitcher plant
s. Many live underground in marine and freshwater caves, sinkhole
s, or stream beds. Copepods are sometimes used as bioindicator
s (see particle (ecology)
).
and the carbon cycle
. They are usually the dominant members of the zooplankton
, and are major food organisms for small fish
, whale
s, seabird
s and other crustacean
s such as krill
in the ocean and in fresh water. Some scientists say they form the largest animal biomass
on earth. They compete for this title with Antarctic krill
(Euphausia superba). Because of their smaller size and relatively faster growth rates, however, and because they are more evenly distributed throughout more of the world's oceans, copepods almost certainly contribute far more to the secondary productivity of the world's oceans, and to the global ocean carbon sink than krill
, and perhaps more than all other groups of organisms together. The surface layers of the oceans are currently believed to be the world's largest carbon sink, absorbing about 2 billion tons of carbon a year, the equivalent to perhaps a third of human carbon emissions
, thus reducing their impact. Many plankton
ic copepods feed near the surface at night, then sink (by changing oils into more dense
fats) into deeper water during the day to avoid visual predators. Their moulted exoskeleton
s, faecal
pellets and respiration
at depth all bring carbon
to the deep sea.
About half of the estimated 13,000 described species of copepods are parasitic and have strongly modified bodies. They attach themselves to fish, sharks, marine mammals, and many kinds of invertebrates such as molluscs, tunicates, or corals. They live as endo- or ectoparasites on fish or invertebrates in fresh water as well as in marine environments.
Copepods are typically 1 to 2 mm (0.0393700787401575 to 0.078740157480315 in) long, with a teardrop shaped body and large antennae
. Although like other crustacean
s they have an armoured exoskeleton
, they are so small that in most species this thin armour, and the entire body, is almost totally transparent. Some polar copepods reach 1 centimetre (0.393700787401575 in). Copepods have a compound, median single eye, usually bright red and in the centre of the transparent head; subterranean species may be eyeless. Like other crustaceans, copepods possess two pairs of antennae
; the first pair are often long and conspicuous.
Copepods typically have a short, cylindrical body, with a rounded or beaked head. The head is fused with the first one or two thoracid
segments, while the remainder of the thorax has from three to five segments, each with limbs. The first pair of thoracic appendages are modified to form maxillipeds, which assist in feeding. The abdomen
is typically narrower than the thorax, and contains five segments without any appendages, except for some tail-like "rami" at the tip.
Because of their small size, copepods have no need of any heart
or circulatory system (the members of the order Calanoida have a heart but no blood vessels), and most also lack gill
s, being able to absorb oxygen directly into their bodies. Their excretory system consists of maxillary glands.
ated for fast conduction.
Many of the smaller copepods feed directly on phytoplankton
, catching cells singly. Some of the larger species are predators of their smaller relatives. Many benthic copepods eat organic detritus or the bacteria that grow in it, and their mouth parts are adapted for scraping and biting. Herbivorous copepods, particularly those in rich cold seas, store up energy from their food as oil droplets while they feed in the spring and summer plankton blooms. These droplets may take up over half of the volume of the body in polar species.
This scene was scanned with the ecoSCOPE
, an underwater high-speed microscope. Very little is known about the details of these kinds of predator/prey interactions, in spite of their importance for global processes, because copepods are difficult to keep in the laboratory and lose most of their escape capacity, and herring are very fast, alert and evasive organisms and flee from normal camera systems or scuba divers
.
Some copepods have extremely fast escape response
s when a predator is sensed and can jump with high speed over a few millimeters (see animated image). Many species have neurons surrounded by myelin
(for increased conduction speed), which is very rare among invertebrate
s (other examples are some annelid
s and malacostraca
n crustaceans like palaemonid
shrimp and penaeids
). Even rarer, the myelin is highly organized, resembling the well-organized wrapping found in vertebrates (Gnathostomata
).
Finding a mate in the three-dimensional space
of open water is challenging. In some copepods the problem is solved by pheromone
chemicals emitted by the swimming female, which leaves a trail in the water that the male can follow to locate the female.
and transfers it to the female's genital opening with his thoracic limbs. Eggs are sometimes laid directly into the water, but many species enclose them within a sac attached to female's body until they hatch. In some pond-dwelling species, the eggs have a tough shell and can lie dormant for extended periods if the pond dries up.
The eggs hatch into nauplius larvae, which consists of a head with a small tail
, but no thorax or true abdomen. The nauplius moults five or six times, before emerging as a "copepodid larva". This stage resembles the adult, but has a simple, unsegmented abdomen and only three pairs of thoracic limbs. After a further five moults, the copepod finally takes on the adult form. The entire process from hatching to adulthood can take anything from a week to a year, depending on the species.
(crustaceans). Some authors consider the copepods to be a full class
. The group contains ten orders
with some 14,000 described species
. A scientist who studies copepods is a copepodologist.
.
Live copepods are popular among hobbyists who are attempting to keep particularly difficult species such as the mandarin dragonet, or to breed other marine species in captivity. In a saltwater aquarium, copepods are typically stocked in the refugium
.
, Boston, Massachusetts, and San Francisco. This is not usually a problem in treated water supplies. In some tropical countries, such as Peru
and Bangladesh
, a correlation has been found between copepods and cholera
in untreated water, because the cholera bacteria attach to the surfaces of planktonic animals. The larvae of the guinea worm must develop within a copepod's digestive tract before being transmitted to humans. The risk of infection with these diseases can be reduced by filtering out the copepods (and other matter), for example with a cloth filter
.
Copepods have been used successfully in Vietnam
to control disease-bearing mosquitoes such as Aedes aegypti
that transmit dengue fever and other human parasitic diseases.
The copepods can be added to water-storage containers where the mosquitoes breed. Copepods, primarily of the genera Mesocyclops
and Macrocyclops (such as Macrocyclops albidus
), can survive for periods of months in the containers, if the containers are not completely drained by their users. They will attack, kill, and eat the younger 1st and 2nd instar
larvae of the mosquitoes. This biological control method is complemented by community trash removal and recycling to eliminate other possible mosquito-breeding sites. Because the water in these containers is drawn from uncontaminated sources such as rainfall, there is little risk of contamination by cholera bacteria, and in fact no cases of cholera have been linked to copepods introduced into water-storage containers. Trials using copepods to control container-breeding mosquitoes are underway in several other countries, including Thailand
and the southern United States
.
The matter of copepods in the water supply, however, has raised a problem for Jewish people who observe Kashrut
in that copepods, being crustaceans, are not kosher, and are not small enough to be ignored as non-food microscopic organisms (since some specimens can be seen with the naked eye). The discovery of copepods in the New York water supply in the summer of 2004 in particular caused significant debate in rabbinical circles and caused many observant Jews to buy filters for their water.
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s found in the sea and nearly every freshwater
Freshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...
habitat
Habitat (ecology)
A habitat is an ecological or environmental area that is inhabited by a particular species of animal, plant or other type of organism...
. Some species are plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
ic (drifting in sea waters), some are benthic
Benthos
Benthos is the community of organisms which live on, in, or near the seabed, also known as the benthic zone. This community lives in or near marine sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths.Many organisms...
(living on the ocean floor), and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests, bogs, springs, ephemeral ponds and puddles, damp moss, or water-filled recesses (phytotelmata
Phytotelmata
Phytotelma is a term for water bodies held by plants. The water accumulated on these plants may serve as substratum for associated fauna, and often the fauna associated with phytotelmata is unique....
) of plants such as bromeliads and pitcher plant
Pitcher plant
Pitcher plants are carnivorous plants whose prey-trapping mechanism features a deep cavity filled with liquid known as a pitfall trap. It has been widely assumed that the various sorts of pitfall trap evolved from rolled leaves, with selection pressure favouring more deeply cupped leaves over...
s. Many live underground in marine and freshwater caves, sinkhole
Sinkhole
A sinkhole, also known as a sink, shake hole, swallow hole, swallet, doline or cenote, is a natural depression or hole in the Earth's surface caused by karst processes — the chemical dissolution of carbonate rocks or suffosion processes for example in sandstone...
s, or stream beds. Copepods are sometimes used as bioindicator
Bioindicator
Biological indicators are species used to monitor the health of an environment or ecosystem. They are any biological species or group of species whose function, population, or status can be used to determine ecosystem or environmental integrity. An example of such a group are the copepods and other...
s (see particle (ecology)
Particle (ecology)
In marine and freshwater ecology, a particle is a small object. Particles can remain in suspension in the ocean or freshwater, however they eventually settle and accumulate as sediment. Some can enter the atmosphere through wave action where they can act as cloud condensation nuclei...
).
Ecology
Planktonic copepods are important to global ecologyEcology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...
and the carbon cycle
Carbon cycle
The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth...
. They are usually the dominant members of the zooplankton
Zooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...
, and are major food organisms for small fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
, whale
Whale
Whale is the common name for various marine mammals of the order Cetacea. The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which belong to suborder Odontoceti . This suborder also includes the sperm whale, killer whale, pilot whale, and beluga...
s, seabird
Seabird
Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...
s and other crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s such as krill
Krill
Krill is the common name given to the order Euphausiacea of shrimp-like marine crustaceans. Also known as euphausiids, these small invertebrates are found in all oceans of the world...
in the ocean and in fresh water. Some scientists say they form the largest animal biomass
Biomass
Biomass, as a renewable energy source, is biological material from living, or recently living organisms. As an energy source, biomass can either be used directly, or converted into other energy products such as biofuel....
on earth. They compete for this title with Antarctic krill
Antarctic krill
Antarctic krill, Euphausia superba, is a species of krill found in the Antarctic waters of the Southern Ocean. It is a shrimp-like crustacean that lives in large schools, called swarms, sometimes reaching densities of 10,000–30,000 individual animals per cubic metre...
(Euphausia superba). Because of their smaller size and relatively faster growth rates, however, and because they are more evenly distributed throughout more of the world's oceans, copepods almost certainly contribute far more to the secondary productivity of the world's oceans, and to the global ocean carbon sink than krill
Krill
Krill is the common name given to the order Euphausiacea of shrimp-like marine crustaceans. Also known as euphausiids, these small invertebrates are found in all oceans of the world...
, and perhaps more than all other groups of organisms together. The surface layers of the oceans are currently believed to be the world's largest carbon sink, absorbing about 2 billion tons of carbon a year, the equivalent to perhaps a third of human carbon emissions
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...
, thus reducing their impact. Many plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
ic copepods feed near the surface at night, then sink (by changing oils into more dense
Density
The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...
fats) into deeper water during the day to avoid visual predators. Their moulted exoskeleton
Exoskeleton
An exoskeleton is the external skeleton that supports and protects an animal's body, in contrast to the internal skeleton of, for example, a human. In popular usage, some of the larger kinds of exoskeletons are known as "shells". Examples of exoskeleton animals include insects such as grasshoppers...
s, faecal
Feces
Feces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus or cloaca during defecation.-Etymology:...
pellets and respiration
Respiration (physiology)
'In physiology, respiration is defined as the transport of oxygen from the outside air to the cells within tissues, and the transport of carbon dioxide in the opposite direction...
at depth all bring carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
to the deep sea.
About half of the estimated 13,000 described species of copepods are parasitic and have strongly modified bodies. They attach themselves to fish, sharks, marine mammals, and many kinds of invertebrates such as molluscs, tunicates, or corals. They live as endo- or ectoparasites on fish or invertebrates in fresh water as well as in marine environments.
Characteristics
Antenna (biology)
Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....
. Although like other crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s they have an armoured exoskeleton
Exoskeleton
An exoskeleton is the external skeleton that supports and protects an animal's body, in contrast to the internal skeleton of, for example, a human. In popular usage, some of the larger kinds of exoskeletons are known as "shells". Examples of exoskeleton animals include insects such as grasshoppers...
, they are so small that in most species this thin armour, and the entire body, is almost totally transparent. Some polar copepods reach 1 centimetre (0.393700787401575 in). Copepods have a compound, median single eye, usually bright red and in the centre of the transparent head; subterranean species may be eyeless. Like other crustaceans, copepods possess two pairs of antennae
Antenna (biology)
Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....
; the first pair are often long and conspicuous.
Copepods typically have a short, cylindrical body, with a rounded or beaked head. The head is fused with the first one or two thoracid
Thorax
The thorax is a division of an animal's body that lies between the head and the abdomen.-In tetrapods:...
segments, while the remainder of the thorax has from three to five segments, each with limbs. The first pair of thoracic appendages are modified to form maxillipeds, which assist in feeding. 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...
is typically narrower than the thorax, and contains five segments without any appendages, except for some tail-like "rami" at the tip.
Because of their small size, copepods have no need of any heart
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
or circulatory system (the members of the order Calanoida have a heart but no blood vessels), and most also lack gill
Gill
A 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...
s, being able to absorb oxygen directly into their bodies. Their excretory system consists of maxillary glands.
Physiology
Copepods have a variety of sensory capabilities. The most noteworthy are bristle-like setae that act as mechanoreceptors responding to flow that causes bending. An array of such sensors allows detection of patterns of water flow around the body caused by approaching prey or predator, and the copepod can distinguish between the two. The sensors are highly specialized for sensitivity and the nerves are even myelinMyelin
Myelin is a dielectric material that forms a layer, the myelin sheath, usually around only the axon of a neuron. It is essential for the proper functioning of the nervous system. Myelin is an outgrowth of a type of glial cell. The production of the myelin sheath is called myelination...
ated for fast conduction.
Behavior
The second pair of antennae are the main source of propulsion, beating like oars to pull the animal through the water.Many of the smaller copepods feed directly on phytoplankton
Phytoplankton
Phytoplankton are the autotrophic component of the plankton community. The name comes from the Greek words φυτόν , meaning "plant", and πλαγκτός , meaning "wanderer" or "drifter". Most phytoplankton are too small to be individually seen with the unaided eye...
, catching cells singly. Some of the larger species are predators of their smaller relatives. Many benthic copepods eat organic detritus or the bacteria that grow in it, and their mouth parts are adapted for scraping and biting. Herbivorous copepods, particularly those in rich cold seas, store up energy from their food as oil droplets while they feed in the spring and summer plankton blooms. These droplets may take up over half of the volume of the body in polar species.
EcoSCOPE
The ecoSCOPE is an optical sensor system, deployed from a small remotely operated vehicle or fibre optic cable, to investigate behavior and microdistribution of small organisms in the ocean.-Deployment:...
, an underwater high-speed microscope. Very little is known about the details of these kinds of predator/prey interactions, in spite of their importance for global processes, because copepods are difficult to keep in the laboratory and lose most of their escape capacity, and herring are very fast, alert and evasive organisms and flee from normal camera systems or scuba divers
Scuba diving
Scuba diving is a form of underwater diving in which a diver uses a scuba set to breathe underwater....
.
Some copepods have extremely fast escape response
Escape response
Escape response, escape reaction, or escape behaviour is a possible reaction in response to stimuli indicative of danger, in particular, it initiates an escape motion of an animal...
s when a predator is sensed and can jump with high speed over a few millimeters (see animated image). Many species have neurons surrounded by myelin
Myelin
Myelin is a dielectric material that forms a layer, the myelin sheath, usually around only the axon of a neuron. It is essential for the proper functioning of the nervous system. Myelin is an outgrowth of a type of glial cell. The production of the myelin sheath is called myelination...
(for increased conduction speed), which is very rare among invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s (other examples are some annelid
Annelid
The annelids , formally called Annelida , are a large phylum of segmented worms, with over 17,000 modern species including ragworms, earthworms and leeches...
s and malacostraca
Malacostraca
Malacostraca is the largest of the six classes of crustaceans, containing over 25,000 extant species, divided among 16 orders. Its members display a greater diversity of body forms than any other class of animals, and include crabs, lobsters, shrimp, krill, woodlice, scuds , mantis shrimp and many...
n crustaceans like palaemonid
Palaemonidae
Palaemonidae is a family of crustaceans of the order Decapoda. They belong to the infraorder Caridea, which contains the true shrimp; while some freshwater palaemonid species are known as "prawns", the family belongs to the suborder Pleocyemata like all true shrimp, whereas the true prawns are...
shrimp and penaeids
Penaeidae
Penaeidae is a family of prawns, although they are often referred to as penaeid shrimp. It contains many species of economic importance, such as the tiger prawn , whiteleg shrimp, Atlantic white shrimp and Indian prawn. Many prawns are the subject of commercial fishery, and farming, both in marine...
). Even rarer, the myelin is highly organized, resembling the well-organized wrapping found in vertebrates (Gnathostomata
Gnathostomata
Gnathostomata is the group of vertebrates with jaws. The term derives from Greek γνάθος "jaw" + στόμα "mouth". Gnathostome diversity comprises roughly 60,000 species, which accounts for 99% of all living vertebrates...
).
Finding a mate in the three-dimensional space
Three-dimensional space
Three-dimensional space is a geometric 3-parameters model of the physical universe in which we live. These three dimensions are commonly called length, width, and depth , although any three directions can be chosen, provided that they do not lie in the same plane.In physics and mathematics, a...
of open water is challenging. In some copepods the problem is solved by pheromone
Pheromone
A pheromone is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting outside the body of the secreting individual to impact the behavior of the receiving individual...
chemicals emitted by the swimming female, which leaves a trail in the water that the male can follow to locate the female.
Life cycle
During mating, the male copepod grips the female with his first pair of antennae, which is sometimes modified for this purpose. The male then produces an adhesive package of spermSpermatophore
A spermatophore or sperm ampulla is a capsule or mass created by males of various animal species, containing spermatozoa and transferred in entirety to the female's ovipore during copulation...
and transfers it to the female's genital opening with his thoracic limbs. Eggs are sometimes laid directly into the water, but many species enclose them within a sac attached to female's body until they hatch. In some pond-dwelling species, the eggs have a tough shell and can lie dormant for extended periods if the pond dries up.
The eggs hatch into nauplius larvae, which consists of a head with a small tail
Telson
The telson is the last division of the body of a crustacean. It is not considered a true segment because it does not arise in the embryo from teloblast areas as do real segments. It never carries any appendages, but a forked "tail" called the caudal furca is often present. Together with the...
, but no thorax or true abdomen. The nauplius moults five or six times, before emerging as a "copepodid larva". This stage resembles the adult, but has a simple, unsegmented abdomen and only three pairs of thoracic limbs. After a further five moults, the copepod finally takes on the adult form. The entire process from hatching to adulthood can take anything from a week to a year, depending on the species.
Classification
Copepods form a subclass belonging to the subphylum CrustaceaCrustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
(crustaceans). Some authors consider the copepods to be a full class
Class (biology)
In biological classification, class is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, order, family, genus, and species, with class fitting between phylum and order...
. The group contains ten orders
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
with some 14,000 described species
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...
. A scientist who studies copepods is a copepodologist.
Copepods in marine aquariums
Live copepods are used in the saltwater aquarium hobby as a food source and are generally considered beneficial in most reef tanks. They are scavengers and also may feed on algae, including coralline algaeCoralline algae
Coralline algae are red algae in the order Corallinales. They are characterized by a thallus that is hard because of calcareous deposits contained within the cell walls...
.
Live copepods are popular among hobbyists who are attempting to keep particularly difficult species such as the mandarin dragonet, or to breed other marine species in captivity. In a saltwater aquarium, copepods are typically stocked in the refugium
Refugium (fishkeeping)
In fishkeeping, a refugium is an appendage to a marine, brackish, or freshwater fish tank that shares the same water supply. For some applications water flow is limited in order to protect plants or animals that require slow flow...
.
Water supplies
Copepods are sometimes found in the public mains water supply, especially systems where the water is not filtered, such as New York CityNew York City
New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...
, Boston, Massachusetts, and San Francisco. This is not usually a problem in treated water supplies. In some tropical countries, such as Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
and Bangladesh
Bangladesh
Bangladesh , officially the People's Republic of Bangladesh is a sovereign state located in South Asia. It is bordered by India on all sides except for a small border with Burma to the far southeast and by the Bay of Bengal to the south...
, a correlation has been found between copepods and cholera
Cholera
Cholera is an infection of the small intestine that is caused by the bacterium Vibrio cholerae. The main symptoms are profuse watery diarrhea and vomiting. Transmission occurs primarily by drinking or eating water or food that has been contaminated by the diarrhea of an infected person or the feces...
in untreated water, because the cholera bacteria attach to the surfaces of planktonic animals. The larvae of the guinea worm must develop within a copepod's digestive tract before being transmitted to humans. The risk of infection with these diseases can be reduced by filtering out the copepods (and other matter), for example with a cloth filter
Cloth filter
Developed for use in Bangladesh, the cloth filter is a simple and cost-effective appropriate technology method for reducing the contamination of drinking water...
.
Copepods have been used successfully in Vietnam
Vietnam
Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...
to control disease-bearing mosquitoes such as Aedes aegypti
Aedes aegypti
The yellow fever mosquito, Aedes aegypti is a mosquito that can spread the dengue fever, Chikungunya and yellow fever viruses, and other diseases. The mosquito can be recognized by white markings on legs and a marking in the form of a lyre on the thorax...
that transmit dengue fever and other human parasitic diseases.
The copepods can be added to water-storage containers where the mosquitoes breed. Copepods, primarily of the genera Mesocyclops
Mesocyclops
Mesocyclops is a genus of copepod crustaceans in the family Cyclopidae. Mesocyclops is used as a nontoxic and inexpensive form of biological mosquito control.-Biological control:...
and Macrocyclops (such as Macrocyclops albidus
Macrocyclops albidus
Macrocyclops albidus is a larvivorous copepod species.-Ecology:It makes its habitat in still fresh waters such as in residential roadside ditches, pools, ponds, and other environments with sufficient food supply....
), can survive for periods of months in the containers, if the containers are not completely drained by their users. They will attack, kill, and eat the younger 1st and 2nd 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...
larvae of the mosquitoes. This biological control method is complemented by community trash removal and recycling to eliminate other possible mosquito-breeding sites. Because the water in these containers is drawn from uncontaminated sources such as rainfall, there is little risk of contamination by cholera bacteria, and in fact no cases of cholera have been linked to copepods introduced into water-storage containers. Trials using copepods to control container-breeding mosquitoes are underway in several other countries, including Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
and the southern United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
.
The matter of copepods in the water supply, however, has raised a problem for Jewish people who observe Kashrut
Kashrut
Kashrut is the set of Jewish dietary laws. Food in accord with halakha is termed kosher in English, from the Ashkenazi pronunciation of the Hebrew term kashér , meaning "fit" Kashrut (also kashruth or kashrus) is the set of Jewish dietary laws. Food in accord with halakha (Jewish law) is termed...
in that copepods, being crustaceans, are not kosher, and are not small enough to be ignored as non-food microscopic organisms (since some specimens can be seen with the naked eye). The discovery of copepods in the New York water supply in the summer of 2004 in particular caused significant debate in rabbinical circles and caused many observant Jews to buy filters for their water.
See also
- Hunting copepods
- World Association of CopepodologistsWorld Association of CopepodologistsThe World Association of Copepodologists is a non-profit organization created to promote research on copepods by facilitating communication among interested specialists.WAC currently has about 130 members worldwide...