An
endangered arthropod is defined here as any of a number of
speciesIn biology, a species is:* a taxonomic rank or* a unit at that rank ....
within the
phylumIn biology, a phylum ["Phylum" is adopted from the Greek phylai, the clan-based voting groups in Greek city-states.] is a taxonomic rank below Kingdom and above Class...
Arthropoda, whose
extinctionIn biology and ecology, extinction is the end of an organism or group of taxa. The moment of extinction is generally considered to be the death of the last individual of that species...
is likely in the foreseeable future (e.g. within one human generation). Estimating the number of arthropod endangered species is extremely difficult, primarily because a vast number of the species themselves are not yet named or described. Furthermore, according to Deyrup and Eisner: "The rate of destruction and degradation of natural habitats is currently so great that there are not nearly enough biologists to even catalog the
arthropodAn arthropod is an invertebrate that has an exoskeleton , a segmented body, and jointed attachments called appendages. Arthropods are animals belonging to the Phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
species that are suddenly on the edge of extinction." In any case, independent estimates indicate that there are millions of undocumented arthropods on Earth.
Arthropods as a group have been very successful
organismIn biology, an organism is any living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homeostasis as a stable whole...
s on this planet, comprising over half of all the higher lifeforms. However
the expanding human populationOverpopulation is a condition where an organism's numbers exceed the carrying capacity of its habitat. In common parlance, the term usually refers to the relationship between the human population and its environment, the Earth....
has led to demise of many arthropod species through the mechanisms of
deforestationDeforestation is the clearance of naturally occurring forests by the processes of logging and/or burning of trees in a forested area. There are several reasons deforestation occurs: trees or derived charcoal can be sold as a commodity and used by humans, while cleared land is used as pasture,...
, conventional farming, slash-and-burn methods in the tropics,
habitat fragmentationHabitat fragmentation is a process of environmental change important in evolution and conservation biology. As the name implies, it describes the emergence of discontinuities in an organism's preferred environment...
via urban development, excessive use of
pesticideA pesticide is a substance or mixture of substances used to kill a pest.A pesticide is any substance or mixture of substance intended for:- preventing, destroying, repelling or mitigating any pest....
s and even the success of forest fire suppression.
The social/political practice whereby a species is given a formal designation as "Endangered" or "Protected" is a different matter, called "
Conservation statusThe conservation status of a species is an indicator of the likelihood of that species remaining extant either in the present day or the near future...
", and discussed elsewhere; see Endangered Species List for the
United StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
, and
IUCN Red ListThe IUCN Red List of Threatened Species , founded in 1948, is the world's most comprehensive inventory of the global conservation status of plant and animal species. The International Union for the Conservation of Nature and Natural Resources is the world's main authority on the conservation...
for international purposes.
An
endangered arthropod is defined here as any of a number of
speciesIn biology, a species is:* a taxonomic rank or* a unit at that rank ....
within the
phylumIn biology, a phylum ["Phylum" is adopted from the Greek phylai, the clan-based voting groups in Greek city-states.] is a taxonomic rank below Kingdom and above Class...
Arthropoda, whose
extinctionIn biology and ecology, extinction is the end of an organism or group of taxa. The moment of extinction is generally considered to be the death of the last individual of that species...
is likely in the foreseeable future (e.g. within one human generation). Estimating the number of arthropod endangered species is extremely difficult, primarily because a vast number of the species themselves are not yet named or described. Furthermore, according to Deyrup and Eisner: "The rate of destruction and degradation of natural habitats is currently so great that there are not nearly enough biologists to even catalog the
arthropodAn arthropod is an invertebrate that has an exoskeleton , a segmented body, and jointed attachments called appendages. Arthropods are animals belonging to the Phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
species that are suddenly on the edge of extinction." In any case, independent estimates indicate that there are millions of undocumented arthropods on Earth.
Arthropods as a group have been very successful
organismIn biology, an organism is any living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homeostasis as a stable whole...
s on this planet, comprising over half of all the higher lifeforms. However
the expanding human populationOverpopulation is a condition where an organism's numbers exceed the carrying capacity of its habitat. In common parlance, the term usually refers to the relationship between the human population and its environment, the Earth....
has led to demise of many arthropod species through the mechanisms of
deforestationDeforestation is the clearance of naturally occurring forests by the processes of logging and/or burning of trees in a forested area. There are several reasons deforestation occurs: trees or derived charcoal can be sold as a commodity and used by humans, while cleared land is used as pasture,...
, conventional farming, slash-and-burn methods in the tropics,
habitat fragmentationHabitat fragmentation is a process of environmental change important in evolution and conservation biology. As the name implies, it describes the emergence of discontinuities in an organism's preferred environment...
via urban development, excessive use of
pesticideA pesticide is a substance or mixture of substances used to kill a pest.A pesticide is any substance or mixture of substance intended for:- preventing, destroying, repelling or mitigating any pest....
s and even the success of forest fire suppression.
The social/political practice whereby a species is given a formal designation as "Endangered" or "Protected" is a different matter, called "
Conservation statusThe conservation status of a species is an indicator of the likelihood of that species remaining extant either in the present day or the near future...
", and discussed elsewhere; see Endangered Species List for the
United StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
, and
IUCN Red ListThe IUCN Red List of Threatened Species , founded in 1948, is the world's most comprehensive inventory of the global conservation status of plant and animal species. The International Union for the Conservation of Nature and Natural Resources is the world's main authority on the conservation...
for international purposes. Only a tiny fraction of the planet's endangered arthropods are formally recognized as such, as no one has ever evaluated the conservation status of the vast majority of arthropod species.
Difficulty of estimating numbers of species
It is difficult to estimate the total number of endangered arthropod species, since many of the taxa themselves have not been recorded. For example, in
North AmericaNorth America is the northern continent of the Americas, situated in the Earth's northern hemisphere and in the western hemisphere. It is bordered on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the southeast by the Caribbean Sea, and on the west by the North Pacific...
the estimated number of insect species exceeds 163,000, of which only about two thirds are taxonomically known. An even greater discovery awaiting, over 72 percent of North American
arachnidArachnids are a class of joint-legged invertebrate animals in the subphylum Chelicerata. All arachnids have eight legs, although in some species the front pair may convert to a sensory function. The term is derived from the Greek word , meaning "spider".Most arachnids are terrestrial...
s are yet to be named and described.
The total number of living arthropod species is probably in the tens of millions. One conservative estimate puts the number of arthropod species in tropical forests alone at six to nine million species As a consequence of all of the above, most published estimates of the total number of endangered insects and arachnids are probably low by at least an order of magnitude. Conservatively at least eighty percent of all living animal species are arthropods.
Ecological risks
Since arthropods constitute the majority of the faunal biomass on Earth, their role is vital to the survival of large numbers of
insectivoreAn insectivore is a type of carnivore with a diet that consists chiefly of insects and similar small creatures.Although individually small, insects exist in enormous numbers and make up a very large part of the animal biomass in almost all non-marine environments...
s and other animals that prey upon arthropods. This includes enormous numbers of
mammalMammals are a class of vertebrate animals whose females are characterized by the possession of mammary glands while both males and females are characterized by sweat glands, hair, three middle ear bones used in hearing, and a neocortex region in the brain.Mammals are divided into three main...
s, avafauna,
fishA fish is any aquatic vertebrate animal that is typically ectothermic , covered with scales, and equipped with two sets of paired fins and several unpaired fins...
es,
reptileReptiles, or members of the class Reptilia, are air-breathing, generally "cold-blooded" amniotes that generally have skin covered in scales or scutes. They are tetrapods and lay amniote eggs, whose embryos are surrounded by the amnion membrane...
s and
amphibianAmphibians , such as frogs, toads, salamanders, newts, and caecilians, are ectothermic animals that metamorphose from a juvenile water-breathing form, to an adult air-breathing form. Though amphibians typically have four limbs, the Caecilians are notable for being limbless. Unlike other land...
s; in addition, arthropods constitute the bulk of faunal
pollinatorA pollinator is the biotic agent that moves pollen from the male anthers of a flower to the female stigma of a flower to accomplish fertilization or syngamy of the female gamete in the ovule of the flower by the male gamete from the pollen grain...
s, so that the survival of
cropCrop may refer to:* Crop, a plant grown and harvested for agricultural use* Crop , a plant cultivated and harvested on an annual basis considered as personal property as opposed to real property. This allows a tenant farmer return for harvesting purposes even after lease of land espires. Crop may...
s as well as millions of natural
floraIn botany, flora has two meanings. The first meaning, flora of an area or of time period, refers to all plant life occurring in an area or time period, especially the naturally occurring or indigenous plant life...
species depend on robust and
biologically diverseBiodiversity is the variation of life forms within a given ecosystem, biome, or for the entire Earth. Biodiversity is often used as a measure of the health of biological systems...
arthropod populations.
The survival of diverse arthropods is essential to propagation of higher animals on the
food chainFood chains describe the eating relationships between species within an ecosystem or a particular living place. Many types of food chains or webs are applicable depending on habitat or environmental factors...
, e.g. those species who prey upon the insectivores and other taxa that consume arthropods. Even if constant arthropod total biomass results after certain arthropod extinctions, the ecosystem stability is compromised by reduction in species numbers. Thus extinction of arthropods species threaten to make extinct hundreds of thousands, if not millions, of higher order birds, amphibians, reptiles and mammals.
Mechanisms of arthropod endangerment
There are several pathways of endangerment for arthropods; however, most of them stem from the pressures of an
expanding human populationOverpopulation is a condition where an organism's numbers exceed the carrying capacity of its habitat. In common parlance, the term usually refers to the relationship between the human population and its environment, the Earth....
and resulting actions humans take to produce food, housing, transportation and recreation. Probably the greatest hazard to arthropod survival is
agricultureAgriculture is the production of food and goods through farming and forestry. Agriculture was the key development that led to the rise of human civilization, with the husbandry of domesticated animals and plants creating food surpluses that enabled the development of more densely populated and...
, due to the ever increasing demand of the human population to feed its expanding numbers. Agriculture typically results in a
monocultureMonoculture is the agricultural practice of producing or growing one single crop over a wide area. The term is also applied in several fields. It is usually developed by extensive growing farmers.-Land use:...
that cannot support the
biodiversityBiodiversity is the variation of life forms within a given ecosystem, biome, or for the entire Earth. Biodiversity is often used as a measure of the health of biological systems...
nurtured by the predecessor natural environment. Normally arthropods represent the largest number of species that are displaced by such farming. In tropical regions the major threat is slash-and-burn agricultural techniques pursued by indigenous peoples in their sometimes only available method of subsistence.
PesticideA pesticide is a substance or mixture of substances used to kill a pest.A pesticide is any substance or mixture of substance intended for:- preventing, destroying, repelling or mitigating any pest....
use is also a major threat to arthropod species survival. Pesticides may have an intended effect of killing specified insects in a farming environment; however, considerable pesticide applications kill unintended species by the lack of specificity of most chemical formulations; moreover, much of the insect mortality arises from pesticide
runoffSurface runoff is the water flow which occurs when soil is infiltrated to full capacity and excess water, from rain, snowmelt, or other sources flows over the land. This is a major component of the hydrologic cycle. Runoff that occurs on surfaces before reaching a channel is also called a nonpoint...
entering
surface waterSurface water is water collecting on the ground or in a stream, river, lake, wetland, or ocean; it is related to water collecting as groundwater or atmospheric water....
s or from transporting toxic chemicals to downgradient environments.
Habitat fragmentationHabitat fragmentation is a process of environmental change important in evolution and conservation biology. As the name implies, it describes the emergence of discontinuities in an organism's preferred environment...
has special methods of endangerment beyond the amount of land consumed by the fragmenting agent. As an example, consider the construction of a
highwayA highway is a main road for travel by the public between important destinations, such as cities and states. Highway designs vary widely and can range from a two-lane road without margins to a multi-lane, grade separated motorway. In English and U.S...
, whose width is an effective barrier to arthropod migration. Many arthropods never migrate more than about 200 feet from their place of birth, so a
freewayA freeway is a type of road designed for safer high-speed operation of motor vehicles through the elimination of at-grade intersections. This is accomplished by preventing access to and from adjacent properties and eliminating all cross traffic through the use of grade separations and...
or
dual carriagewayA dual carriageway or divided highway is a road or highway in which the two directions of traffic are separated by a central barrier or strip of land, known as a central reservation or median...
effectively fragments many arthropod colonies such that they cannot interact. Studies have shown the greater vulnerability to extinction where habitats are fragmented.
Example endangered arthropods
The following is a very small fraction of the potentially hundreds of thousands of endangered arthropods, limited to species which have been formally recognized as to their special conservation status:
- Alabama cave shrimp
The Alabama cave shrimp, Palaemonias alabamae, is a species of albinistic, obligate cave shrimp in the family Atyidae. The species was first collected in 1958 by Thomas Poulson. They are found only in two caves in the state of Alabama...
(Palaemonias alabamae)
- California freshwater shrimp (Syncaris pacifica)
- Delhi Sands flower-loving fly
The Delhi Sands flower-loving fly is a mydid fly in the genus Rhaphiomidas, and the only fly presently on the Endangered Species List....
(Rhaphiomidas terminatus abdominalis), due to severely limited range of habitat and development
- Kentucky cave shrimp
The Kentucky cave shrimp, Palaemonias ganteri, is an eyeless, troglobite shrimp. It lives in Kentucky and is found in caves in three counties of Kentucky. The shrimp's skin has no pigment; the species is nearly transparent and closely resembles its nearest relative, the Alabama cave shrimp.The...
(Palaemonias ganteri)
- Salt Creek tiger beetle
The Salt Creek tiger beetle, Cicindela nevadica lincolniana, is a critically endangered subspecies of tiger beetle endemic to the saline wetlands of northern Lancaster County, Nebraska, adjacent to and immediately to the north of the city of Lincoln. It is a predatory insect, using its mandibles...
(Cicindela nevadica lincolniana)
- San Bruno elfin butterfly
The San Bruno elfin butterfly is a U.S. Federally listed endangered subspecies which inhabits rocky outcrops and cliffs in coastal scrub on the San Francisco peninsula...
(Incisalia mossii bayensis), due to limited range of habitat and development encroachment
- Smith's blue butterfly
Smith's blue butterfly, Euphilotes enoptes smithi, is an organism in the family Lycaenidae, which is also known as the "gossamer wing" family...
(Euphilotes enoptes smithidue), to human overpopulationOverpopulation is a condition where an organism's numbers exceed the carrying capacity of its habitat. In common parlance, the term usually refers to the relationship between the human population and its environment, the Earth....
of coastThe coast is defined as where the land meets the sea. A precise line that can be called a coastline cannot be determined due to the process of tides. The term "coastal zone" can be used instead, which is a spatial zone where interaction of the sea and land processes occurs...
al dunes areas and associated highwayA highway is a main road for travel by the public between important destinations, such as cities and states. Highway designs vary widely and can range from a two-lane road without margins to a multi-lane, grade separated motorway. In English and U.S...
and land development
- Spruce-fir moss spider
The Spruce-fir moss spider is an endangered species of spider found at high elevations in the southern Appalachian Mountains. First identified in 1923, they inhabit moss that grows on rocks underneath the forest canopy....
(Microhexura montivaga)
- Tasmanian giant freshwater crayfish
The Tasmanian giant freshwater crayfish is the largest freshwater invertebrate in the world. The species is only found in Tasmania, and is listed as a vulnerable species due to habitat loss and over fishing. It is also severely threatened by siltation and de-snagging of streams as decaying wood...
(Astacopsis gouldi)
- Tooth cave spider
The tooth cave spider is a 1/16 inch long arachnid. It is endemic to Texas and is considered an endangered species....
(Neoleptoneta myopica)
- White-clawed crayfish
Austropotamobius pallipes is an vulnerable European freshwater crayfish, and the only species of crayfish native to the British Isles . Its common names include white-clawed crayfish and Atlantic stream crayfish...
(Austropotamobius pallipes)
Benefits of arthropod extinction
There are some who favour the selective extinction of a small number of arthropod species, especially those that are disease vectors, such as certain
mosquitoMosquito is a common insect in the family Culicidae...
s. While
malariaMalaria is a vector-borne infectious disease caused by a eukaryotic protist of the genus Plasmodium. It is widespread in tropical and subtropical regions, including parts of the Americas, Asia, and Africa. Each year, there are approximately 350–500 million cases of malaria, killing between one and...
, for example, is spread by a number of mosquito species, there are other ways to combat this disease other than the extinction of entire species. Thus extinction of a limited number of arthropods must be considered as a controversial subject.