Invertebrates
Springtail
Collembola · also called springtails, snow fleas
A springtail is one of the most abundant animals you have never noticed. There can be a hundred thousand in a square metre of soil, quietly eating fungus and dead leaves and keeping the ground alive. Touch one and it vanishes — flung several centimetres by a spring-loaded lever it keeps folded under its belly like a cocked mousetrap.
Overview
Springtails are the group Collembola, tiny six-legged arthropods that look like insects but are not — they are their own ancient lineage, with mouthparts tucked inside a pouch in the head. About 9,000 species are known, living in soil, leaf litter, moss, and rotting wood almost everywhere on land, from rainforest to Antarctic rock.
The spring
Most springtails carry a forked appendage, the furcula, folded under the abdomen and latched under tension. Released, it snaps against the ground and catapults the animal several centimetres — an instant, if undirected, escape. Many also have a water-repellent skin so fine they can float dry on a puddle’s surface film; some species live permanently on the water.
Snow fleas and soil health
Some springtails stay active in winter, massing on the snow surface on mild days — “snow fleas” — kept from freezing by an antifreeze protein that stops ice crystals growing. In the soil, by eating fungi and shredding litter, springtails are among the most important recyclers on land and near the base of the food web, and ecologists use their numbers as a quick gauge of soil health.
Status
Least Concern — abundant on every continent, including Antarctica, where they are among the largest fully land-living animals. A few cave and island specialists with tiny ranges are threatened.
Springtail: common questions
Are springtails harmful in the house or garden?
No. Springtails that appear indoors, often in large numbers in damp bathrooms, kitchens, plant pots, or basements, or outdoors on patios and in mulch after rain, are harmless. They do not bite, sting, spread disease, damage sound wood or fabric, or feed on people or pets. They are there because it is damp and there is mould or decaying matter to eat, and they leave or die back when things dry out. In houseplants a big population usually signals overwatering. They are a nuisance and an indicator of excess moisture, not a pest to be feared.
How do springtails jump without legs made for it?
They do not jump with their legs at all. Folded under the abdomen is a two-pronged lever called the furcula, held cocked against a catch like a mousetrap. When the springtail is disturbed, the catch releases, the furcula swings down and strikes the ground, and the reaction flings the animal up to several centimetres, many times its body length, in a fraction of a second. The jump is not aimed, it just gets the animal away from danger fast, after which it often lands, rights itself, and springs again.
What are snow fleas?
Snow fleas are springtails, usually certain dark-coloured species, that remain active through winter and come to the surface of the snow on sunny, mild days, sometimes in such numbers that patches of snow look dusted with soot or pepper. They are feeding on pollen, algae, and organic debris on the snow. They can stay active at freezing temperatures because they produce a special antifreeze protein that latches onto tiny ice crystals and prevents them from growing large enough to damage the animal. They are not fleas, do not bite, and have nothing to do with pets.
Why do springtails matter?
For their sheer numbers and their job. With tens of thousands per square metre across most of the world's soils, springtails are a huge part of the soil animal community, and by eating fungi, shredding dead leaves, and spreading fungal spores and bacteria they speed up decomposition, help build soil structure, and influence which fungi grow around plant roots. They are also near the base of the food web, feeding predatory mites, beetles, spiders, ants, and small vertebrates. Ecologists track springtail numbers and diversity as a quick read on how healthy a soil is.