Threat of extinction for spineless animals

One fifth of invertebrates could be at risk of extinction, according to a report published by scientists from Zoological Society of London (ZSL).

Almost 80 percent of the world's species are invertebrates, with 96 percent of all known land species being invertebrates.

Of over 12,000 species known to be threatened, the review found freshwater invertebrates most at risk, such as molluscs and insects including dragonflies.

Most of the risk factors come from human pressures, according to the report. These include habitat disruption for buildings, agricultural water pollution, domestic sewage, industrial waste, and rising temperatures.

Scientists believe marine invertebrates are also at large risk, though only a small percentage were assessed. Rising ocean pH levels are causing external skeletons to erode and the exploitation of lobsters, crabs and species of shellfish is another factor.

The report from the ZSL describes many invertebrates as having "bizarre" appearances due to habitat adaptions, however, this environmental sensitivity does provide a benefit towards survival.

Scientists also included the economic worth of the animals in the report. For example, according to the National Audit Office, honeybees were worth £200m to the UK economy for pollinating in 2007.

Head of the Indicators and Assessments unit at ZSL, Dr Ben Collen, said: "[Invertebrates] are important because they play a number of roles in eco-systems that provide humans with great benefits.

"Invertebrates are particularly good at providing things like water filtration and nutrient recycling. All of the flowers that we see around us, many of the crops that we grow and eat are pollinated for free by insects."

Dr Collen adds: "While the cost of saving [invertebrates] will be expensive, the cost of ignorance to their plight appears to be even greater."