The Little Things that run the World – the other 97%

When I started out as a ranger I think I was made to run more mini-beast hunts than anything else. From nursery to early teens I began to realise that this is one of the best ways children can begin to connect with nature.

It takes no specialist knowledge and is a wonderful way to explore a world of decaying logs and upturned stones that you may have never experienced before.

Mini-beasts are one of the more recent names for “Invertebrates”. Invertebrates are animals without a backbone or bony skeleton. Also known as wee beasties and creepy crawlies.

You may have some creepy-crawly hang-ups. I do. I am slightly (quite) afraid of spiders but pretend to be a little bit more frightened than you are and most children will boldly show you a female spider and her nest and reassure you there is nothing to be scared about.

They are by far the largest group in the animal kingdom: 97 percent of all animals are invertebrates. So far, 1.25 million species have been found and described, most of which are insects, and there are millions more to be discovered.

The total number of invertebrate species could be 5, 10, or even 30 million, compared to just 60,000 vertebrates.

A two-banded longhorn beetle. Like other longhorn beetles it lays its eggs in dead wood, often using conifer trees, where they bore deep, broad tunnels until they are ready to pupate after about two years

A really straight-forward way to break this immense variety down into manageable chunks is to think of mini-beasts as belonging to 6 camps.


A mini-beast with a soft, smooth and slimy body that slowly moves using one muscular foot.

Slugs and snails

Leopard slugs and their relatives will only mate when they’re dangling upside down from a thread of mucus.
A snail trail is a substance that’s somewhere between a liquid and a solid. It flows a bit like a liquid, but at the molecular level, it’s more organized. It can be both sticky and lubricating, and it actually slurps up water.  It helps them move and climb challenging surfaces – even a pane of glass!

Only a few slug species are pests. Most are critical members of land and water ecosystems all around the world with ecological benefits for the slow-worms, thrushes, hedgehogs, badgers and other animals further up the food chain. Most are scavengers and eat dead and rotting plants; leaf litter; dead wood; fallen fruit; animal droppings; carrion and mouldering compost.

The Annelids

Segmented worms.

A mini-beast with a long, creeping, soft, segmented body.

A wriggling ecosystem engineer

The impact of earthworms on ecosystems is just simply massive. By their activity in the soil, earthworms offer so many benefits including increased nutrient availability, better drainage, and a more stable soil structure, all of which underpin agricultural productivity. Worms feed on plant debris (dead roots, leaves, grasses, manure) and soil.

Charles Darwin in a piece called the Formation of Vegetable Mould states

“It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organised creatures.”

Myriapods – the “many legged ones”.

The centipedes and millipedes.

A mini-beast that looks a little like a worm with lots of legs.

A flat-backed millipede. I instinctively thought this was a centipede but with (I think) 2 pairs of legs per segment its a millipede.

Millipedes usually have round bodies, and have two pairs of legs on each body segment. They move slowly and often tunnel into soil and dead leaves. Nearly all millipede species are decomposers: they eat dead leaves, fungi, and detritus. If another animal threatens them, they often curl up, and some give off pungent chemicals to protect themselves. 

A millipede motionless and curled up defensively

Centipedes are usually flattened, and only have one pair of legs per segment. They are quick voracious nocturnal predators, eating any small animals they can catch. Both centipedes and millipedes need a damp humid environment to survive, and mostly live on or just under the ground.

Arachnids – Spiders

A mini-beast with a body in 2 parts and eight legs.

A female spider and her nest. Spider eggs are laid in a silken sac. She will stay with it until she dies in autumn. 

A study of an undisturbed grass field in Sussex found 5.5 million spiders per hectare.

They are important predators and prey for a multitude of other animals. Spiders eat lots of insects, mostly those smaller than themselves.

Taken as a whole spiders’ primary niche in nearly every ecosystem is controlling insect populations. 

Furthermore, spiders are an important food source for birds, lizards, wasps, and mammals.

Spiders use silk in many ways – to wrap and immobilise prey, to spin webs for catching prey using sticky silk, to make draglines which connect the spider to the web as a safety line and to parachute in the wind to find new food sources.


Wood lice

A mini-beast with a bumpy exoskeleton and seven body segments, each with a pair of legs.

By Martin Cooper from Ipswich, UK – Common striped woodlouse

Turn over any log, rock, piece of wood or other debris and you are likely to find woodlice. There are 37 species found across the UK in almost any habitat except some cold highland areas.

Though they look a bit like millipedes, woodlice are crustaceans and are related to shrimps and crabs. This makes woodlice one of the few truly land-living crustaceans.

As well as living off and recycling decaying wood, common rough woodlice feed on leaf litter, fungi, fallen fruit, dead animals and faeces. They share their habitat with spiders, beetles and centipedes which eat them and they provide a main food source for shrews.


A mini-beast with its body in 3 parts – head, thorax and abdomen – and six legs.

Having said this they truly come in diverse shapes and sizes, from butterflies to beetles and dragonflies to grasshoppers.

Common blue Butterfly
 A Dor or Dung beetle. The adults dig out a nesting tunnel under suitable dung and line the nest with dung for the larvae to feed on.
A 4 spotted chaser Dragonfly.
A meadow grasshopper. Grasshoppers go through a series of moults, shedding their exoskeletons as they grow, turning into adults in June who feed on plants and grass. 

Over one million species of insects have been discovered and described but it is estimated that there may be as many as 10 million species on earth. This means there are approximately 1.4 billion insects for every person on Earth.

Insects serve as the base of the food web, eaten by everything from birds to small mammals to fish.

They provide priceless “services” to us, including plant pollination, nutrient cycling and waste disposal. Three-fourths of all flowering plants are pollinated by insects, as well as the crops that produce more than one third of the world’s food supply.

The next time you go for a walk I urge you take some time to stretch out in a grassy meadow for 5 minutes and gently turn some logs over and place them back again and meet the multitudes.


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