Threatened arthropods

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Risiocnemis seidenschwarzi, a critically endangered damselfly from the Philippines. An IUCN Red List assessment in 2009 estimated fewer than 50 mature adult individuals remained.[1]

Threatened arthropods are defined here as any of a number of

Arthropoda, whose extinction is likely in the foreseeable future. Estimating the number of threatened arthropod 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,[2] "The rate of destruction and degradation of natural habitats is currently so great that there are not nearly enough biologists to even catalog the arthropod species that are suddenly on the edge of extinction." In any case, independent estimates indicate that there are millions of undocumented arthropods on Earth.[3]

Arthropods as a group have been very successful

forest fire
suppression.

The social/political practice whereby a species is given a formal designation as "Endangered" or "Protected" is a different matter, called "

Endangered Species List for the United States, and IUCN Red List
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

The endangered Delhi Sands flower-loving fly.

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 America the estimated number of insect species exceeds 163,000, of which only about two thirds are taxonomically known.[4] An even greater discovery awaiting, over 72 percent of North American arachnids are yet to be named and described.[4]

The total number of living arthropod species is probably in the tens of millions.

tropical forests alone at six to nine million species.[5] 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.[4] Conservatively at least eighty percent of all living animal species are arthropods.[6]

Ecological risks

Since arthropods constitute the majority of the faunal biomass on Earth, their role is vital to the survival of large numbers of

avafauna, fishes, reptiles and amphibians; in addition, arthropods constitute the bulk of faunal pollinators, so that the survival of crops as well as millions of natural flora species depend on robust and biologically diverse arthropod populations.[7]

The survival of diverse arthropods is essential to propagation of higher animals on the food chain, 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.[citation needed]

Mechanisms of arthropod endangerment

Aerial photo of the Anjajavy Forest, Madagascar
which holds a number of endangered arthropods.

Most endangerment of arthropod populations is from habitat destruction by growing human populations and related human activities such as agriculture, construction and transportation. [citation needed]

chemicals to downgradient environments.[citation needed
]

freeway or dual carriageway effectively fragments many arthropod colonies such that they cannot interact. Studies have shown the greater vulnerability to extinction where habitats are fragmented.[8]

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:

The endangered white-clawed crayfish

See also

References

  1. doi:10.2305/iucn.uk.2009-2.rlts.t59770a12016276.en
    .
  2. ^ Mark A. Deyrup; Thomas Eisner (2001). "Snapshots at the Edge of a Cliff". Wings. 24 (2).
  3. ^ a b Southern Appalachian Information Node: Resources about Arthropods
  4. ^
    S2CID 2671435
    .
  5. ISBN 1-930585-15-2
    (2004)
  6. ^ Anna Thanukos, The Arthropod Story, University of California, Berkeley
  7. ^ Jaboury Ghazoul and R. Uma Shaanker, Sex in Space: Pollination among Spatially Isolated Plants, Biotropica: Volume 36, Issue 2, Page 128, June, 2004
  8. ^ Brigette Michele Braschler, (2005) Effects of Experimental Small-Scale Grassland Fragmentation on the Population Dynamics of Invertebrates PhD Thesis, University of Basel
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