278 Invertebrates at Risk

Definition

Mapped here is data from the IUCN Red List of Threatened Species. "The IUCN Red List Categories and Criteria are intended to be an easily and widely understood system for classifying species at high risk of global extinction."

The map shows invertebrate species excluding molluscs that are at risk of extinction. In the Red List they are assessed as Critically Endangered (CR), Endangered (EN) or Vulnerable (VR). The very precise criteria are largely based on population size or geographic range, and how fast these are falling within a timescale of 3 generations or 10 years, whichever is the longer. "The categorization process is only applied to wild populations inside their natural range, and to populations resulting from benign introductions (attempts to establish a species, for the purpose of conservation, outside its recorded distribution, but within an appropriate habitat and eco-geographical area)." "Extinction is a chance process. A listing in a higher extinction risk category implies a higher expectation of extinction."

Invertebrates are animals without backbones and, excluding molluscs, are about 90% of all known animal species. By far the largest group are insects (about a million species). Insects have a head, a body and an abdomen. Attached to the thorax are 6 legs and usually 4 wings. They include Dragonflies, grasshoppers, earwigs, ants, beetles, flies, butterflies, wasps. There are also about 70,000 spiders with 8 legs, 40,000 crustaceans (including crabs with 10 legs, barnacles, shrimps and on land woodlice), 3,000 centipedes, 10,000 millipedes and about 50,000 other species; worms, sponges etc. Marine species are described as living in FAO Fisheries Areas, and usually assigned to the nearest territory.

Double counting checks on our regional and total figures suggest that invertebrates (excluding molluscs) assessed as Threatened Species are on average assigned to 1.4 territories. Of those assessed, 52% of Insects, 85% of Crustaceans and 51% of other species have been given Threatened Species status. However with only 0.16% of species assessed, anything between 0.1% and 56% of all invertebrate species (excluding molluscs) could qualify as Threatened Species.

Data sources

The source of this data is the International Union for Conservation of Nature and Natural Resources, 2006, Red List of threatened species 2004. Tables 5, 6a and 6b.

For more source and data information, see the technical notes for 267, Species Extinct.

Click here to view detailed data source references

The quotation used to accompany this map is sourced from the abstract of a paper for the Society for Risk Analysis’s Annual Meeting in 2000. The paper was entitled ‘An Overview of the Role of Invertebrates in Risk Assessment’ and the author is R. T. Ryti. The quote was cut slightly for use with the map, the full quote reads: “Invertebrates play important roles in nutrient cycling and in creating and maintaining biological diversity. Lay audiences may overlook their significance because many invertebrate species are small or cryptic.” It was sourced from the website below in December 2006:

http://www.riskworld.com/Abstract/2000/SRAam00/ab0ac313.htm

Extra information, used in the text that accompanies the maps, was sourced from Bug Life, in December 2006, at the website below:

http://www.buglife.org.uk

Excel sheet

Below is an explanation of each of the columns in the excel file:

Column A = Unique numerical territory (see 001).

Column B = Region and territory names (see 001).

Column C = Region code (see 001).

Column D = The ISO 3 code, or ISO ALPHA-3 (see 001).

Column E = Number of invertebrate species (excluding molluscs)assessed as threatened species by 2004. From Source Data (Column H).

Column F = Invertebrate species (excluding molluscs) assessed as threatened per 1000 local species assessed for that territory by 2004. This is calculated by dividing the number of other invertebrates at risk in 2004 (Column H) by the count of all species in that territory (Column G) multiplied by 1000 so that the rate per 1000 is given. (F = 1000 * H / G).

Column G = Number of local plant and animal species assessed by 2004. This is calculated by adding the count of animal species and plant species together. The data for this can be found on the source data sheet.

Column H = Number of invertebrate species (excluding molluscs) assessed as threatened species, 2004. This is taken from the source data sheet.