In the serene and rugged terrains of Scotland's Isle of Rum, a remarkable ecological phenomenon is unfolding. The island, known for its red deer population, is now gaining attention for its earthworms, which are not just any earthworms, but giants that are actively transforming the landscape.
A Living Laboratory (Photo : AI Generated/Paw Mozter)
The Isle of Rum, part of the Inner Hebrides, has long been a natural laboratory where scientists have studied the island's ecology.
The earthworms of Rum, however, are proving to be as significant as the well-documented red deer. These invertebrates, acting as "ecosystem engineers," are shaping the landscape in profound ways.
Human Influence and Earthworm Ingenuity
Rum's human history goes back 9,000 years. Bloodstone, a mineral that resembles flint and is used to produce arrowheads and other hunting and cutting tools, is why early humans came here to get it.
Early humans cleared the island of its forests, and the island's humid climate-which receives more than two meters of rain annually-caused soil nutrients to seep out.
The resultant acidic, low-quality soil supported just three earthworm species in small quantities and moorland plants.
However, later human settlers sufficiently enhanced the soils to make a living as tenant farmers in a few coastal communities.
They used kelp seaweeds to fertilize the cultivated land and enrich soil quality. Then, during the "Highland clearances" of about 200 years ago, these industrious people were forcibly expelled from their communities on Rum (as well as from a large portion of Scotland).
There are still noticeable ridges and furrows on Rum called "lazybeds" at locations like Harris, Dibidil, and Kilmory.
These show the locations of the meticulously hand-dug fields used to cultivate potatoes and other crops. The crops were grown on elevated slopes, and the furrows provided drainage.
These soils continue to host more earthworms and remain more fruitful than nearby places even after two centuries since the last tillage.
Beneath stands of trees planted a century ago in Papadil, another abandoned village that is rarely seen these days, a dark forest soil has emerged.
Researchers discovered enormous, one-centimeter-diameter earthworm holes inside these trees.
Researchers discovered the largest Lumbricus terrestris recorded in the UK in the wild on an island devoid of moles and badgers, with plenty of leaf litter for feeding and minimal human disturbance.
The common species of earthworms found on Rum, Lumbricus terrestris, are larger and heavier than the typical earthworm by a factor of three. The island worms were observed by the researchers to grow to a length of over 15 inches (40 cm).
Their size has increased due to the absence of predators and the rich soil. Worms in Rum may live up to 10 years due to its "optimum conditions," but worms in other parts of the UK often only live two years.
The research draws on university scientists' investigations in 2006 to 2011 of "very large" worm burrows. Kevin Butt, professor at the University of Central Lancashire who led the study, said: "I first noticed the large worm burrows in 2005, so I had my suspicions that there may be some pretty big worms in the area. We went back out to investigate this the following year and finding worms of this size was very exciting, especially when the Natural History Museum team confirmed that they had no specimens like this."
He added: "There are still unanswered questions and we plan to continue our research to find out as much as possible about these creatures. We're also looking forward to exploring more rural areas in the UK and abroad, in the hope that we will make more exciting discoveries like this."
The discovery of these giant earthworms has sparked interest and further research into their impact on the ecosystem.
Their ability to alter the soil and landscape composition is a testament to the interconnectedness of life and the environment, even in the most remote and seemingly isolated places.
