why conserve invertebrates?

Xerces Society

Why are invertebrates important?

Biologist E. O. Wilson has called invertebrates "little things that run the world," because of their number, variety and influence on larger organisms and even entire ecosystems. These diverse and wonderful creatures-butterflies, beetles, bees, ants, dragonflies, spiders, snails, lobsters, and starfish, to name but a few-are at the heart of a healthy environment. They build the stunning coral reefs of our oceans, give color to the sparkling fields of springtime wildflowers, and serve as food for countless other animals.

Invertebrates are a part of nearly every food chain, either directly, as food for fishes, amphibians, reptiles, birds, mammals, or indirectly, as agents in the endless recycling of nutrients in the soil. Food webs are often dependent on invertebrate species performing essential services such as pollination or seed dispersal. Simply put, a world without invertebrates would be impoverished, and ecosystems would collapse.

There is another reason to educate people about the importance of invertebrates. As people grow to respect and understand the importance of insects and other small creatures, they will in turn understand and respect all life. Because many invertebrates only need small areas to thrive, they can serve as an effective introduction to people on the importance of protecting habitat.

Invertebrate diversity and biomass
The Animal Kingdom has just over a million scientifically described species categorized into thirty-two phyla. The phylum Arthropoda (insects, spiders, crustaceans, millipedes, and centipedes among others) has an estimated 1,085,000 identified species, or 82 percent of the total identified animal species, and with all other invertebrates (excluding viruses and bacteria) the number reaches 1,238,000 or 94 percent. The phylum Chordata, which includes all fish, birds, and mammals, contains around 45,000 (3 percent) species, of which only 4,000 (0.03 percent) are mammals. It is estimated that five to eight million insect species have not been identified or discovered, while only 5,000 to 10,000 species of Chordates may await discovery and description. Certain marine taxa, particularly small benthic organisms, are nearly as poorly known as terrestrial arthropods, suggesting that we have greatly underestimated oceanic species diversity as well.

E.O. Wilson

E.O. Wilson

Invertebrates are also the undisputed heavyweights of the planet. In the oceans, zooplankton and shrimp-like krill develop vast surface blooms of incredible mass. In the United States the biomass of earthworms and arthropods is estimated at nearly 1,000 kg/ha, while the comparative biomass of human beings and all other terrestrial vertebrates is just 36 kg/ha. In other words, for every pound of terrestrial vertebrate, there are 28 pounds of earthworm and arthropod! If you total the weight of all land animals, arthropods alone comprise over 85 percent of the total.

Invertebrates importance to functioning ecosystems
The sheer number and mass of invertebrates reflects their enormous ecological impact. Admittedly, some have a negative impact on humans, either by harming us directly (as disease agents) or attacking our interests. Even so, all adverse effects combined are insignificant compared to their beneficial actions. Invertebrates are a part of nearly every food chain, either directly, as food for other insects, fishes, amphibians, reptiles, birds, mammals, and other arthropods, or indirectly, as agents in the endless recycling of nutrients in the soil. Insects, worms, and mites are extremely important in helping microbes break down dung and dead plant and animal matter. Ninety-nine percent of human and animal waste is thought to be decomposed by invertebrates. The perpetuation of food webs is often dependent on critical species performing essential services such as pollination or seed dispersal. Most of the pollination of both human food crops and all other plants come from invertebrates, especially native bees. In the United States, some ninety agricultural crops are cross-pollinated by insects.

Some invertebrates are "keystone species," playing particularly important roles in maintenance of biotic communities. Coral reefs are perhaps the most dramatic example, providing a wide range of niches for a diversity of plants and perhaps one-third of all fish species. Pollinators are also often considered keystone species , as their presence in an ecosystem ensures the continued reproduction and survival of plants, and in turn the other wildlife relying on these plants. There are dozens more examples of how invertebrates benefit ecosystems and humans as natural biological control, food (such as lobster and shrimp and the many insects consumed by different cultures), and as potential cures for human disease. Without insects, most of the terrestrial life forms on this planet would quickly disappear.

What should be done to protect invertebrates?
Detailing a precise conservation plan for invertebrates would take volumes. The widespread destruction of the Earth's biodiversity occurring today must be matched by a conservation response of an order of magnitude greater than currently exists. Ultimately, the key to protection of any species is protecting its habitat. Many scientists advocate community-level conservation for noncharismatic taxa, and community-wide studies appear to offer a practical way to gather information about the diversity and distribution of little known taxa. We should move forward with this information gathering wherever possible. Although protecting whole communities is a valid scientific approach, one of the best methods of protecting species, the Endangered Species Act, is based on species rather than ecosystem conservation.

Habitat Protection. Large swaths of land protected as wilderness or for wide ranging species or set-aside in conservation easements will ultimately benefit invertebrates. Some invertebrates only need small areas to thrive, and, indeed, backyard gardens can help some pollinators. Working in other countries to protect nature reserves, or promoting ecologically responsible butterfly and scarab ranches, encourages habitat protection in developing countries. Habitat also needs to be protected for marine species. We need marine reserves managed for marine species, not marine reserves where commercial fishing and other destructive activities are allowed, as is often the case now.

Status reviews and listing petitions. The formal listing of species as threatened or endangered under federal or state endangered species legislation, as sensitive or indicator species under US Forest Service National Forest Management Act regulations, or even under lists from non-governmental organizations such as IUCN, has been an extremely effective habitat protection tool. Groups and individuals should work to protect threatened and endangered invertebrates as well as more charismatic megafauna and ensure that agencies and land managers realize the importance of conserving invertebrates.

Research. Before we can work to protect some invertebrates we need to know at a minimum if populations are stable or declining, and we need to understand their habitat needs. Many invertebrates have not even been identified. In the long run, more emphasis needs to be placed on invertebrate systematics and taxonomy so that these species can be identified and cataloged. Research needs to go hand in hand with conservation, for there is little use for a catalog of extinct species.

Education. The conservation of invertebrates will necessitate a greater understanding by the general public, scientists, land managers, and conservationists of the extraordinary value that these organisms provide. It is unlikely that many people will develop affection or an affinity for these animals, but it may be that a more compelling depiction of the extraordinary contributions to human welfare and survival made by invertebrates will do much to improve the public attitude toward these organisms. An ambitious public education program is needed to enhance recognition of the positive values of invertebrates, and indeed, all biological diversity.

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