THE ANIMAL FILES

Common earthworm

Lumbricus terrestris

A fallen leaf can travel down an earthworm’s burrow.

A common earthworm can disappear into a deep vertical burrow and return to the surface to collect food. Its muscles, tiny bristles and feeding habits link movement to soil mixing. The familiar worm on a path is only a brief view of an animal whose activity crosses soil layers.[1]

Follow the evidence ↓
Common earthworm
Image: Donald Hobern from Copenhagen, Denmark · Commons · CC BY 2.0
Burrow
Deep, largely vertical passages[1]
Food
Mostly dead plant material[1]
Grip
Tiny bristles called setae[1]

Movement without legs

Circular and longitudinal muscles change the shape of a fluid-supported body. Small setae gain purchase against the surroundings, allowing muscular contractions to produce progress rather than simply sliding in place.[1]

Bringing litter below ground

This species is an anecic earthworm: it builds deep burrows but feeds at the surface. Leaves pulled downward connect surface litter with mineral soil. Casts contain mixed organic and mineral material. A burrow is consequently more than shelter; it is also part of a route along which material moves between layers.[1]

An uneven leaf menu

Dead leaves are important food, but preferences vary among tree species. Chemical composition, including calcium content, is associated with those choices. The worm also consumes other decomposing material.[1]

A COMMON MIX-UP

Does a deep burrow mean it finds all its food deep underground?

No. It surfaces to feed and pulls litter down. Resting location and feeding location are different questions.[1]

TRY A LITTLE REASONING

What might connect a leaf disappearing at the surface with mixed casts nearby?

Reveal the explanation

Feeding transports organic material into the soil and digestion returns mixed casts. Those observations suggest a material pathway, not simply an animal hiding from view.[1]

Sources & editorial notes

Adapted and translated from the cited Wikipedia revisions, with source-linked reasoning. Image credit and licence are listed separately above.

Adapted and translated from Wikipedia contributors; exact revisions are linked below. CC BY-SA 4.0

  1. Wikipedia contributors — Lumbricus terrestris (adapted and translated; exact revision)
  2. NCBI Taxonomy — Lumbricus terrestris (identity and game lineage)

Last fact check:

One discovery leads to another

European medicinal leechTwo suckers, three jaws, and a meal that must stay liquid.Hirudo medicinalis ↗Christmas tree wormTwo little trees are feeding structures.Spirobranchus giganteus ↗Common liver flukeA leaf-shaped body with an active outer coat.Fasciola hepatica ↗