Invertebrate Biodiversity

Invertebrate is a catch-all term referring to any animal that lacks a backbone, encompassing a very wide range of animals such as mollusks, worms, corals, insects, crabs, and sponges.

Invertebrates represent, by far, the largest group of animal species on Earth. Of the 32 animal phyla, 31 are invertebrates. They comprise 95% (1.25 million) of all described species in the Animal Kingdom.

In terms of biomass, species diversity and ecological function, they dominate global ecosystems. And as with all life on Earth, they are vulnerable to human activity and to climate change.

The American Museum of Natural History reports that the three most endangered animal groups in the US are freshwater mussels, crayfish and stoneflies – all invertebrates. “Almost 70% of all freshwater mussel species are in need of immediate conservation measures, compared to just 16% of mammals and 14% of birds,” the museum says. Indeed, 10 freshwater mussels are listed on the Vermont Threatened and Endangered Species list.

According to the Vermont Agency for Natural Resources (ANR), Vermont hosts at least 21,400 invertebrate species. The Vermont Natural Heritage Inventory tracks site-specific information on 221 rare or endangered invertebrates. The ANR, along with the Vermont Center for Ecostudies, sponsors numerous projects, many using citizen scientists, to catalog the presence and distribution of invertebrates in the state. On the watch list: tiger beetles, butterflies, dragon and damselflies, mussels, bees and other types of invertebrates.

The evolutionary history of invertebrates stretches back 580 million years in the fossil record to primitive jellyfish. In order to move out of their original ocean environment, invertebrates evolved numerous adaptations to living on land that allowed for “breathing” without drying out.

As a consequence, species may react in various ways to changes in precipitation, temperature, and salinity, among other factors. In addition, they often inhabit multiple ecosystems during their lifespans. For example, some beetles begin life as larvae underground, and then emerge to live as adults above ground. Climate driven changes in temperature and moisture above and below ground will affect invertebrates, with lasting consequences across ecosystems. In some instances, specific invertebrate populations might crash, in others they may surge dramatically. These population changes will have cascading effects on the welfare of other animals and humans.

The ecosystem functions invertebrates provide encompass soil creation and aeration, decomposition, nutrient cycling, water purification, pollination, seed dispersal and habitat creation. They also form part of almost every food chain.

Protecting and conserving invertebrates will require more research and policy changes. There are invertebrate species yet to be discovered, and we lack data on those we know about. We need to know better their current population sizes, their needs for survival and adaptation to climate driven changes, how they influence beneficial and harmful change across multiple ecosystems, and what factors drive changes in their numbers. We have some evidence that habitat loss, chemical pollution, urbanization, land-use change and landscape simplification affect invertebrate numbers. We also have evidence that policy changes can have positive benefits, as when the Clean Water Act contributed to improvements for freshwater insects. Invertebrates need to be included in environmental impact assessments, and their needs considered when creating and managing conserved lands and parks. Participating in invertebrate citizen science projects like those at the Vermont Center for Ecostudies, supporting farms that practice organic and regenerative agriculture, switching off outdoor lights or installing motion- sensing lights, planting native plants and removing non-natives, using pollinator friendly mowing regimes, leaving leaves on the ground, leaving bare soil in your garden instead of heavily mulching everywhere – these are all significant ways you can support invertebrates.