While often mistaken for worms, the creatures well-known for curling into a tight coil when disturbed are millipedes. These fascinating invertebrates employ this behavior as a primary defense mechanism.
Millipedes: Masters of Defense
Millipedes are not worms but are arthropods, belonging to a group known as myriapods. They are distinct from true worms (like earthworms) in several ways, most notably their many legs and hard outer shell.
When disturbed, handled, or even when they are no longer living, millipedes instinctively coil into a tight spiral. This defensive posture serves to protect their softer underside and vulnerable parts from potential threats.
Key Characteristics of Millipedes:
- Appearance: They are typically very dark brown, with a shiny, hard shell that can feel "crunchy" to the touch. Their bodies are long and cylindrical.
- Size: Millipedes commonly encountered range from 1 to 1 1/4 inches in length.
- Legs: Unlike worms, millipedes possess numerous legs, with two pairs attached to most of their body segments.
- Harmless Nature: Despite their appearance or defensive curling, millipedes are harmless to humans.
Why Do Millipedes Curl?
The act of coiling is a passive defense strategy. By forming a tight spiral, millipedes present their tough, armored exoskeleton to the outside, shielding their more delicate legs, head, and ventral (underside) surface. This makes them difficult for predators to grasp or injure.
Distinguishing Millipedes from True Worms
It's common for people to confuse millipedes with worms due to their segmented, cylindrical body shape. However, several key differences set them apart:
| Feature | Millipede | True Worm (e.g., Earthworm) |
|---|---|---|
| Classification | Arthropod (Myriapoda) | Annelid (segmented worm) |
| Legs | Many pairs (two pairs per body segment) | None |
| Body Covering | Shiny, hard exoskeleton (shell) | Soft, moist skin |
| Defense | Curls into a tight coil | Primarily burrows, recoils, no coiling |
| Diet | Primarily decaying plant matter | Organic matter in soil |
Understanding these differences helps in correctly identifying the creatures you might encounter in your garden or surroundings. The curling behavior is a unique and effective survival strategy for millipedes.
