What are springtails and why would humans not exist without them?

In an era long past, when the Earth was hot and humid, marine life thrived. The sea teemed with early squids, eel-like fish, and sea worms, all hunting smaller marine animals — like the springtails.

Yet, above ground, life had not yet ventured. Such was the state of our planet about 450 million years ago, at the tail end of the Ordovician period.

The warm oceans provided an idyllic haven for marine creatures, but change was imminent. Earth’s once balmy land masses began to freeze, as a vast ice cap steadily expanded across its surface.

The previously hospitable waters transformed into cold, unforgiving habitats. Within a brief span, our world witnessed its second-worst mass extinction event. Half of all known species were obliterated.

Springtails are everywhere

However, against the odds, the springtail emerged as a survivor. These insect-like creatures are minute, with the largest among them only stretching to six millimeters. At a casual glance, you might mistake them for a garden-variety insect, but they command a unique evolutionary branch.

Over 9,000 species of springtails have been identified, and their habitats range from the soils of backyards to the foliage of dense forests. Interestingly, they get their name from a forked tail, also known as furcula, which allows them to jump up to 10 centimeters high when threatened, a notable feat for such a tiny creature.

Amidst the ever-expanding list of their fascinating traits, springtails have another impressive adaptation: antifreeze proteins.

Tiny animals and antifreeze proteins

A fascinating new study by researchers from Aarhus University and Queen’s University in Canada suggests that the springtail may have been the first animal to ever produce antifreeze proteins. Prior to this discovery, the scientific consensus was that animals did not develop this ability until much later.

“We knew that antifreeze proteins had developed independently of each other several times during evolutionary history. Fish have them. Insects have them. Some spiders have them. But until we saw these results, we didn’t know that they’d developed so early in the animal world,” says Professor Martin Holmstrup of the Department of Ecoscience at Aarhus University.

How to find springtails

Martin Holmstrup and his colleagues collected the springtails from Denmark, Iceland, and Greenland for their lab. Finding them isn’t difficult. You might even discover them in your garden. Here’s how:

1. Take a handful of soil or foliage from your garden and put it in a sieve.
   
2. Position an adjustable lamp above the sieve and set a tray underneath.
   
3. The lamp’s heat drives the springtails to seek cooler surroundings, causing them to fall through the sieve. You can then observe them scurrying about in the tray.

What the researchers learned

Holmstrup, who oversees nearly 20 species of springtails in his laboratory, sent samples to his Canadian colleagues to ascertain when these creatures first developed the antifreeze protein. With DNA sequencing technology, the team searched for sequences associated with antifreeze protein production across a wide range of species.

Their findings? The gene mutation leading to antifreeze protein genesis happened during the Ordovician period.

“The calculations show that springtails developed the antifreeze protein long before other animals. It didn’t happen for fish and insects until a million years later. Although plants and microorganisms, such as bacteria and single-celled algae, might have developed a similar mechanism even earlier,” Holmstrup adds.

Springtails dry out like raisins

While these proteins are vital, springtails have another survival mechanism. To protect their cells from freezing, they undergo a form of hibernation, drying out completely. In this state, their metabolism drops to near-undetectable levels.

“You can compare them to a grape that dries into a raisin in a process reminiscent of freeze-drying. The springtails shrink and become small, wrinkly critters in winter. And then, when spring arrives, they absorb water and swell back to normal size,” Holmstrup explains.

Antifreeze proteins and the food industry

The concept of antifreeze proteins first emerged in the mid-20th century. For years, scientists were puzzled at how Arctic fish could thrive in icy waters that, based on temperature alone, should have frozen them. It wasn’t until the late 1960s that the American researcher Arthur DeVries identified these proteins in Arctic fish, noting their ability to prevent ice from forming within their cells.

Today, the implications of these proteins reach beyond our understanding of evolutionary survival. The food industry, particularly in the frozen sector, has taken a keen interest.

Holmstrup shares, “The genes that encode the antifreeze proteins in fish have been copied into industrial yeast cell cultures. This makes the yeast produce the very useful proteins, which can then be added to different foods.”

For instance, companies like Unilever have integrated these proteins into ice creams, resulting in enhanced textures and an improved freezing-thawing process. But the potential applications don’t end there.

As Holmstrup concludes, “In the longer term, this effect could be used in connection with the cryopreservation of transplant organs. Other industries like the aerospace and wind turbine industries have also experimented with the proteins. They hope the proteins can protect wings from freezing and needing to be de-iced.”

In understanding the springtail’s evolutionary triumph, we not only gain insight into our planet’s rich past but also draw inspiration for technological advancements in our future.

More about the Ordovician period

Dive deep into Earth’s geologic timeline, and you’ll find the Ordovician Period. Spanning from approximately 485 to 443 million years ago, this epoch, following the Cambrian Period, paints a vivid picture of an ever-evolving world.

A flourishing marine life

The Ordovician Period primarily showcased an explosion in marine life. Oceans covered a vast majority of the Earth’s surface, and within these primordial waters, diverse marine species thrived. Trilobites, brachiopods, graptolites, and nautiloids dominated the oceans. Notably, corals began constructing the first significant reef systems, laying the foundation for an ecosystem we recognize and value today.

However, it wasn’t just about the animals. The first evidence of green algae appeared during this period, indicating the beginnings of plant life that would later colonize the land. The marine plankton diversified, which led to a significant increase in the overall amount of life. This diverse marine food web set the stage for the rapid evolution and proliferation of predatory organisms.

Advancements in ocean dynamics

The world’s continents underwent significant transformation during the Ordovician. The supercontinent known as Gondwana was on a slow journey toward the South Pole. This migration played a key role in shaping oceanic patterns and sea levels. As Gondwana approached the pole, global cooling ensued, setting the stage for the period’s eventual ice age.

The rise of fish

Fish, albeit very early fish, first emerged during the Ordovician Period. Although these early fish lacked jaws, they still represented a significant evolutionary advancement, marking the onset of vertebrates’ dominance in the following periods. These early fish primarily relied on filter feeding, with their soft bodies navigating the depths of the ancient oceans.

Life takes its first steps on land

While the Ordovician seas teemed with life, land remained mostly barren. However, by the end of the period, the first evidence of life on land began to emerge. Early, non-vascular plants called bryophytes likely took root on terrestrial landscapes. These first steps onto land would pave the way for the more advanced plants and animals that would later dominate the Silurian and Devonian periods.

A freezing conclusion

The Ordovician Period did not end quietly. The movement of Gondwana over the South Pole led to widespread glaciation. This global cooling caused a drop in sea levels, which, combined with other yet-to-be-confirmed factors, triggered the Ordovician mass extinction. This catastrophic event wiped out nearly 60% of marine invertebrate genera and 85% of marine invertebrate species.

However, despite its chilling conclusion, the Ordovician Period remains significant for its contributions to Earth’s evolutionary history. It showcased the diversification and dominance of marine life, saw the emergence of the first fish and land plants, and underwent significant geological changes that shaped the Earth as we know it.

The legacy of the Ordovician Period offers us a profound understanding of our planet’s dynamic history and the intricate web of life it nurtures.

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