9 Woodlouse Facts: These Species Remove Heavy Metals from the Ground

Meet the unsung heroes of the undergrowth: the woodlouse! These tiny armored creatures play an important role in the ecosystem. They’ve been around for 300 million years. So, get ready to be amazed by their incredible world with those amazing facts below!

Phylum: Arthropoda
Class: Malacostraca
Order: Isopoda
Suborder: Oniscidea

1. They’re not insects

The woodlouse is a member of the order Isopoda and belongs to the crustacean family. Contrary to their appearance, they are not insects but share a closer relation to lobsters, prawns, or crabs. However, they do not possess an appetizing flavor. Instead, they are often described as having a taste reminiscent of urine.

There are around 4,000 – 7,000 woodlouse species in the world. Within Britain alone, there are 40 species categorized into 10 distinct families. Some types of woodlice include the pink or rosy woodlouse, zebra isopod (zebra pillbug), nosy pill woodlouse, spiky yellow, giant orange, tropical grey, granny grey, dairy cow, or common woodlouse.

The woodlouse appearance

Woodlice exhibit an exoskeleton in shades of dark gray, brown, black, or occasionally reddish-orange with 7 plates. These plates act as armor to protect them from dangers. These creatures boast a total of 14 legs, which are distributed along their thorax. They are quite small, with a size of about 0.7 – 18 mm in length, with a width of approximately 5mm.

They have 2 short antennae on their heads to help them navigate. Their eyes are typically compound and relatively underdeveloped, possibly due to their nocturnal nature and non-predatory feeding behavior.

At the rear of the body, there are small tube-like structures called uropods. These not only aid in navigation but also function as a defense mechanism as they release chemicals to repel potential predators.

2. Habitat

The woodlouse, an intriguing creature that initially lived in the water, underwent a remarkable transformation to become a terrestrial organism during the initial phases of land colonization.

Their presence extends throughout habitats worldwide, excluding Antarctica, encompassing a range of climates from temperate to tropical. These extraordinary beings have effectively adjusted to diverse ecosystems, showcasing their resilience and capacity to live in different environments.

Woodlice clump together. These species can get into your house if there is a suitable environment nearby or in the winter.

Woodlice are social creatures that typically reside in colonies. They prefer to live in moist and dark spaces, such as walls, fallen trees, under stones, leaf piles, soil, and compost piles. Some species, like the common sea slater, are specifically restricted to coastal regions, occupying the crevices of rocks or stranded seaweed as their preferred habitats.

Interesting fact: Spiritual meaning
In certain cultures, the woodlouse holds great significance as a symbol of adaptability and resilience. Its remarkable ability to curl up into a protective ball when faced with danger embodies the crucial lesson of adapting and safeguarding oneself during challenging times.

3. They eat poop

The woodlouse is a herbivore, mainly eating plants. Despite this, it’s classified as a detritivore. This is because the creatures have a strong preference for decaying or decomposing matter, commonly referred to as detritus. Their diet encompasses various forms of decaying substances such as mold, rotting wood, leaves, fungi, mildew, and even the droppings of other animals. Some species also feed on live plants. They even eat the bodies of other deceased woodlice if the need arises.

Although it may appear as a lesser role, detritivores hold immense ecological importance. They play a crucial role in the ecosystem. They are responsible for the breakdown of leaf litter, ensuring the continuity of the nutrient cycle. Without them, the entire system would suffer. Imagine a world without soil, compost, or proper waste disposal; it would be overwhelmed by accumulated waste.

The woodlouse diet

Among detritivores, the woodlouse is classified as a primary decomposer. They contribute to the decomposition process by breaking down larger waste materials into smaller, digestible pieces that facilitate further stages of decomposition.

In their environment, woodlice face a range of predators that pose a significant threat to them. These include frogs, shrews, millipedes, centipedes, toads, spiders (like woodlouse spiders), and birds (pied flycatchers, thrushes, and blackbirds). Baby woodlice, in particular, are exceptionally vulnerable because their shells are less robust.

4. They bring benefits

The woodlouse is not harmful or bad. On the contrary, it provides numerous benefits and poses minimal to no threat to your garden, as it does not harm plants or cause significant damage.

As previously mentioned, woodlice play a vital role in breaking down plant material. They contribute to the composting process and serve as an indicator that the material is effectively decomposing into compost. Although they are sometimes criticized for consuming strawberries, it’s important to note that they only feed on fruit that is already damaged.

These creatures are not dangerous or poisonous. They don’t cause any health problems, nor do they bite or fly. However, their infestation negatively impacts the environment and has become increasingly challenging to control.

One of the remarkable abilities of woodlice is their capacity to eliminate heavy metals like cadmium, arsenic, and lead through ionization, thereby preventing the leaching of metal ions into the soil. This unique trait enables them to thrive even in highly polluted areas.

5. They have more than 200 monikers

Woodlice are called by more than 250 unique names across various cultures and historical periods. In Welsh, they are referred to as “mochyn coed,” which translates to “wood pig,” whereas in Scotland, they are commonly known as “slaters.”

Another name for the woodlouse is “pissabed” – a Netherlands term. In France, people call them “close-doors,” while Swedish speakers identify them as grey “suckers.” These fascinating creatures also bear a multitude of other names, including “cheese logs,” “boat builders,” “chiggy pigs,” “doodle bugs,” “pill bugs,” “monkey peas,” “fat pigs,” “roly polys,” and “potato bugs.”

6. They have a unique defense mechanism

As mentioned above, woodlice can deter predators by releasing an odor-filled chemical thanks to the uropod structures behind their backs. Their dark colors also help their camouflage within their damp and dim environments.

Some species like roly-polies or pill woodlice (Armadillidium vulgareare) even have extraordinary skill. When threatened, they can coil their bodies tightly into a ball, protecting their essential organs from harm. This ability is similar to that of an armadillo.

The act of rolling into a ball can also serve as a conservation tactic during periods of drought, minimizing water loss.

7. They have unique adaptions

The woodlouse displays a preference for nocturnal activities, primarily engaging in behavior during the night. What sets them apart from other crustaceans is their remarkable adaptation to life on land.

One intriguing feature of woodlice is their pale blue blood, which can be attributed to the presence of hemocyanin, a blue pigment containing a copper core. Just as hemoglobin transports oxygen in humans, hemocyanin serves the same purpose in woodlice. When oxygen levels are low, their blood loses its color and becomes colorless.

One of their unique adaptations is their ability to breathe through the gills in their rear legs. They possess branched tubes known as pseudo-trachea on their abdomen. Depending on the species, the quantity of these structures varies from 0 – 5 pairs.

The pseudo-tracheas serve as their respiratory organs. When oxygen comes into contact with the thin layer of water around their legs, it is absorbed into their gills, enabling them to breathe. This is why woodlice need to live in a moist environment, or else they will suffocate when drying out.

However, this doesn’t mean that the woodlouse can survive in water. They will drown if staying underwater for too long.

These remarkable creatures possess a distinctive method for managing waste removal. While bearded dragons excrete powdered waste, woodlice, on the other hand, expel waste in the form of gas.

They accomplish this by generating a potent chemical compound known as ammonia. This highly odorous substance is emitted in gaseous form through their shells, making them stinky. Through this mechanism, woodlice don’t need to pee. This makes them ideal pets.

8. They’re Marsupials

The pouch characteristic is observed in numerous mammalian species. However, it is not exclusive to them, as several other animal groups possess it as well, such as certain isopods such as the Antarctic giant isopod, some frogs, and the woodlouse.

In order to thrive in terrestrial habitats, woodlice have evolved a unique pouch-like structure to safeguard their eggs and offspring. This remarkable pouch mimics the favorable and nurturing conditions typically found in aquatic environments.

woodlouse reproduction
The mother carry her young on the pouch

The mating season of these species occurs in spring. Following breeding, the female lays about 24 eggs within a specialized small brood pouch located beneath her body. After a span of several days, the offspring hatch within the pouch, remaining there as they undergo multiple molting stages. Eventually, the young emerge from the pouch once they’re big enough to sustain themselves independently.

In order to facilitate healthy development, the woodlouse sheds its shell every two months. The molting process takes place in two stages, starting with the shedding of the rear part and then followed by the anterior part. During this time, they will have 2 colors: grey and pink.

In their natural habitat, the lifespan of the woodlouse is about 2 to 4 years, varying based on the specific species.

9. They make ideal pets

Because the woodlouse doesn’t pee, many people keep them as pets. They are low-maintenance creatures and easy to take care of. You just need to give them a humid terrarium with decaying leaf litter and vegetable scraps.

Keeping woodlice offers a delightful opportunity to observe these tranquil miniature architects as they navigate their daily routines and complete their life cycles. It’s quite easy to have up to 100 of them. To ensure their well-being, you should provide adequate hiding spots for them to feel right at home.



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