by From the moon jellyfish to the humble garden snail, invertebrates play a central – and often invisible – role in shaping our world. Species of insects, arachnids, snails, crustaceans, corals, jellyfish, sponges and ectoderms are among the least understood animals on Earth, overshadowed by their vertebrate cousins often numbering in the millions.
We asked scientists to tell us about how invertebrates shape our world and structure its ecosystems – and the unintended consequences of their disappearance.
‘No one likes to go into the pot‘: decomposing the world’s waste
Without shrimps, dung beetles and thousands of fly species, huge amounts of organic matter would not break down and the nutrients would not be recycled through ecosystems. Many invertebrate species feed and breed in plant and animal waste, and play a vital role in their healthy functioning.
“No one likes to walk into the kiss and we often complain that there is too much of it – but things would be much worse without dung beetles and green bottle flies, which eat and break down animal poine removing the smell and creating. fertilizer for our soils,” says Paul Hetherington, director of Buglife.
In the oceans, mussels, clams and lobsters are all important decomposers, and species such as sea cucumbers also play an earthworm-like role.
“Burying sea cucumbers that move through the sediments as part of their daily activities helps to oxygenate them, which is important for many other processes,” said Annie Mercier, of Memorial University of Newfoundland, and co-chair of the International Conservation Union. Nature’s Species Survival Commission (IUCN) sea cucumber specialist group. “Not only are sea cucumbers active recyclers, they are prey for many other animals, including crabs, fish, turtles, sea otters, pinnipeds, eider ducks and more.”
Caffeinated flowers and shrinking pansies: invertebrates that shape the plant world
Bees are known to be vital pollinators of human staples. But beetles, flies and other invertebrates are also essential to help fruit plants and reproduce. One in three mouthfuls eaten by humans is the result of pollination, according to researchers. The role of invertebrates shapes the way plants behave and develop – such as coffee and citrus trees, which reward insects when they visit their flowers.
“Coffee and citrus flowers offer nectar with caffeine, which has a pharmacological effect on honeybees and bees – it enhances their memory of the unique scents emanating from flowers and thus helps the bees find these important food sources in complex floral landscapes,” says Professor Phil Stevenson. , leader of diversity of character and function at Kew Gardens. “In doing so, it helps the flowers get pollinated as the bees are more likely to return.,” He says.
Many plants have evolved to attract specific species of invertebrates, such as prosopanche plants native to South America. The group produces heat to rouse small nitidulidae beetles to spend the night inside. When pollinators disappear, it can also change plants – a study in December found that wild French pansies produced fewer flowers and less nectar as the number of pollinators declined, effectively becoming from rare and evolving insects to self-pollinate, scientists said.
Dave Goulson, a professor of biology at the University of Sussex who specializes in bee ecology, said the disappearance of pollinators was already having dramatic consequences in some parts of the planet.
“In parts of southwest China there are almost no pollinators left, and farmers are forced to pollinate their apples and pears by hand, lest their crops fail. In Europe I have seen farmers pollinating squash plants by hand, and reports are coming in that farmers in parts of Brazil are resorting to hand-pollinating passion fruit,” he wrote in his recent book, Silent Earth.
Breaking down plastic waste
Invertebrates could help break down some of the billions of tonnes of plastic waste produced by humans each year. In 2022, researchers discovered that the larvae of the Zophobas morio, species of beetle, they were able to digest polystyrene and successfully completed their life cycle.
“Within 48 hours … the faeces they produce goes from their normal brown – when they eat bran – to white,” said Dr Chris Rinke from the University of Queensland, co-author of the study.
Architects of coral reefs
More than half a billion people worldwide depend on reefs for food, protection and livelihoods. They are natural barriers to storms, floods and erosion, protecting human settlements, while providing a home for thousands of species of fish. Invertebrates are vital reef builders, but are threatened by the climate crisis.
“Hard-building corals are the architects of coral reefs – they create the physical structure of a reef as new corals grow on the skeletons of dead corals. On a multifaceted reef, the matrix of growth and erosion of old and new skeletons results in complex structures and spaces, creating a three-dimensional habitat for the many reef-dwelling species,” says David Obura, Cordio’s founding director of east Africa and head of Africa. the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES).
Corals are not the only animals that build reefs, says Julia Sigwart, a member of the mollusc specialist group of the IUCN species survival commission, who warns that marine invertebrates are at risk of being ignored.
“Marine invertebrates comprise the vast majority of species diversity in the ocean, including many species that have not yet been described or named. Because they are not as familiar to us as humans, we often make lumps together; many people don’t realize that sponges are animals, let alone that there are thousands of different species,” she says “This leaves a huge risk of species becoming extinct before we even know they exist, with surprising and potentially disastrous consequences. “
Upward predator food chains
The spread of invasive invertebrates can have major consequences for the entire ecosystem. In January, a study found that an ecological chain reaction had led to the introduction of invasive giant ants to Kenya, resulting in fewer zebra kills by lions. Tree cover fell in areas where the large-headed ants had spread, providing less cover for the lions to ambush zebras. Researchers said their findings had a global lesson about the importance of invertebrates.
“Although ants may seem small and unimportant, this could not be further from the truth in holding entire ecosystems together. This recent study shows that native mutualistic ants are the backbone that holds the African Savanna together,” says evolutionary biologist Dr. Corrie Moreau, an ant expert in Cornell University’s Moreau lab.
“When the native ants are displaced from their plant partners by invasive species this causes ripple effects throughout the entire landscape,” she says. “It’s amazing to think that the small but mighty ant can influence the diets of top predators.”
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