Biodiversity faltering: 20% of invertebrates threatened with extinction

Schoenherr’s blue weevil (Eupholus schoenherri) a spectacular blue and turquoise beetle from Indonesian New Guinea. Photo by Rhett A. Butler.

Twenty percent of invertebrates are at risk of extinction, according to a new report that looks at the 12,621 invertebrates assessed by the IUCN Red List to date. Although invertebrates never garner the same conservation attention as big, charismatic animals such as tigers and elephants, they play an undeniable role in maintaining healthy ecosystems. In addition, since invertebrates make-up 80 percent of the world’s species, the report raises new concerns about global biodiversity decline.

“We knew that roughly one fifth of vertebrates and plants were threatened with extinction, but it was not clear if this was representative of the small spineless creatures that make up the majority of life on the planet,” explains co-editor Jonathan Baillie, the Director of Conservation at the Zoological Society of London (ZSL). “The initial findings in this report indicate that 20 percent of all species may be threatened. This is particularly concerning as we are dependent on these spineless creatures for our very survival.”

Invertebrates, which include 97 percent of the world’s animals, are those animals that lack backbones. They span such broad taxonomic categories as insects, molluscs, squid, and even coral reefs. Although generally small (the colossal squid being one large exception), invertebrates play a major role in the environment. From recycling waste to pollinating flowers to food sources, they provide numerous services, many still unrecognized, to human society.

Automeris moth caterpillar displaying its venomous neon green spines. Photo by Rhett A. Butler.

“We need to successfully communicate the significance and value of invertebrate life, if we are to rescue the many thousands of threatened species from the brink of extinction,” said Richard Edwards, Chief Executive of Wildscreen, a partnering organization of the IUCN Red List that uses imagery to raise species profile.

Described as “the most comprehensive assessment” of the Earth’s invertebrates, the report finds that freshwater invertebrates have the highest rate of endangerment. This is not surprising as freshwater species in general are considered more at risk than terrestrial and marine. For example, the report notes that one third of all freshwater molluscs currently face extinction, the same percentage as the world’s amphibians, which are currently stated to be in a crisis.

Malay Red Harlequin Butterfly (Paralaxitta orphua) in Indonesian Borneo. Photo by Rhett A. Butler.

“In contrast, the global extinction risk experienced by flying insects such as dragonflies, damselflies, and butterflies tends to be much closer to that of birds (around one in ten species threatened),” the report reads.

Still, even as the IUCN has now assessed over 12,000 invertebrates this remains less than 1 percent of all known invertebrates, which number over a 1.3 million species. Beetles alone number around 400,000 unique species. In addition, every year scientists usually document over 10,000 new invertebrates.

“Invertebrate assessment has lagged behind the vertebrates [on the IUCN Red List],” the report admits. “One of the often cited reasons is a lack of information. Data are indeed often hard to come by, and are particularly poor for deep water marine invertebrates, and freshwater micro-invertebrates.”

Green sea anemone. Photo by Rhett A. Butler.

However the report goes on to say that progress can be made with a “diverse range of approaches.” For example, freshwater crabs, crayfish, lobsters, cuttlefish, and reef-building corals have all been fully assessed. Meanwhile scientists are working to complete assessments of the world’s squids, octopuses, cone snails, sea cucumbers, and reef-building oysters.

“We are now trying to expand the number of invertebrates species assessed for the IUCN Red List of Threatened Species,” said Simon Stuart, Chair of the IUCN Species Survival Commission, adding that, “I very much hope that the expansion of conservation-related information on invertebrates will give them a much higher conservation profile in future.”

Malay Praying mantis in Suriname. Photo by Rhett A. Butler.