You’ve probably spotted a small, many-legged animal moving across garden soil, under stones, or along a damp path in a park. Those quick, secretive creatures often belong to a group of land-dwelling invertebrates known as myriapods. This group includes well-known animals like centipedes and millipedes, plus smaller and lesser-known relatives you may never notice without looking closely.
What Are Myriapods?
Myriapods are terrestrial invertebrates within the phylum Arthropoda (arthropods). Today, scientists have described more than 16,550 myriapod species worldwide, and some species possess venom or defensive chemicals. In the deep history of life, several ancient arthropods are sometimes discussed as possible evolutionary relatives or early lineages linked to myriapods, including:
Notable Ancient Arthropods Often Mentioned in This Context
Tokummia katalepsis (about 507 million years ago, Cambrian)
Necrogammarus salweryi and Archidesmus loganensis (about 455 million years ago, Silurian)
Key Characteristics of Myriapods
Early myriapods are thought to have included very large forms (some fossil relatives exceeded a meter). Over long periods, their basic body plan has remained recognizable, even though modern species vary widely in size and lifestyle.
Body Size
Depending on the species, size ranges from about 0.2 mm to around 26 cm.
Some species can exceed 30 cm in length.
Exoskeleton
They have a tough exoskeleton that provides support and protection.
Head Structures
A pair of antennae.
The Tömösváry organ (a sensory structure found in many myriapods).
Mandibles for feeding.
Simple eyes (ocelli) in some groups, while others have no eyes.
Trunk and Segmentation
An elongated trunk built from roughly 11 to 181 segments.
Leg pairs are arranged along the trunk, with the number of legs varying greatly by group and species.
Main Types of Myriapods
Myriapods are commonly grouped into four living classes. Each class has its own body plan, leg arrangement, and typical lifestyle.
1) Chilopoda (Centipedes)
Centipedes are active hunters with a flattened body and one pair of legs per trunk segment.
Typical Size and Body Plan
Often 1–2 cm, though some species may reach up to 30 cm.
Trunk can have roughly 19 to 181 segments.
Many species have around 15 pairs of legs, but the number varies across lineages.
Senses
Simple antennae.
May have ocelli (simple eyes), depending on the species.
Diversity
More than 2,500 centipede species have been described.
2) Diplopoda (Millipedes)
Millipedes are usually cylindrical and are famous for their many legs—though they never truly have a thousand.
Typical Size and Body Plan
Commonly 1–30 cm long.
Segments are often fused into “double segments” (each bearing two pairs of legs).
Despite the nickname “thousand-legger,” most have roughly 34 to 400 legs.
Diversity
More than 12,000 millipede species have been described.
3) Symphyla (Symphylans)
Symphylans are tiny, soil-dwelling myriapods that often go unnoticed.
Typical Size and Body Plan
Very small, usually under 8 mm.
Commonly have 12 pairs of legs.
No eyes.
Diversity
About 200 species have been recorded.
4) Pauropoda (Pauropods)
Pauropods are among the smallest terrestrial arthropods, living in moist soil and leaf litter.
Typical Size and Body Plan
Extremely small, usually under 2 mm.
Forked antennae.
Typically 9–11 pairs of legs.
No eyes.
Diversity
Roughly 600 species have been described.
Habitat of Myriapods
Most myriapods prefer humid environments because their bodies can lose water easily. That’s why they’re commonly found in soil, under logs, beneath stones, or in leaf litter. Even so, some species have adapted to dry or semi-desert climates, surviving by hiding during the hottest hours and using microhabitats that retain moisture.
Where They Are Usually Found
Most common in tropical and temperate regions.
Generally absent from very cold mountain zones and polar environments.
Behavior of Myriapods
Many myriapods are nocturnal. During the day, they often shelter in dark, damp places—under bark, stones, fallen branches, or deep in soil cracks.
Defense Strategies
Curling up to protect the softer underside (especially common in millipedes).
Biting in some groups, sometimes accompanied by irritating secretions.
Some can release irritating chemicals or use tiny defensive hairs that cause discomfort.
Are They Dangerous to Humans?
In many cases, defensive bites or secretions are not lethal, but they can be painful. In people, reactions may include swelling, redness, and localized pain that can last for a couple of days, depending on the species and sensitivity of the skin.
Diet: What Do Myriapods Eat?
Feeding habits vary greatly across the four classes, which is one reason they play many different roles in soil and forest ecosystems.
Chilopoda (Centipedes)
Typically active predators.
Use specialized mouthparts to inject venom and subdue prey.
Diplopoda (Millipedes)
Often associated with detritus and decaying plant material.
Some may also consume small animals opportunistically, depending on the species and available food.
Symphyla (Symphylans)
Primarily herbivorous, feeding on plant material in soil environments.
Pauropoda (Pauropods)
Mainly sapropha gous (feeding on decomposing organic matter).
Reproduction of Myriapods
Myriapods reproduce sexually, and fertilization can occur through different strategies depending on the group.
Internal vs. External Transfer
Direct transfer: mating involves contact using specialized reproductive structures (often called gonopods in some groups).
Spermatophore transfer: the male places a spermatophore near the female, who then picks it up and stores it for internal fertilization.
Egg-Laying and Parental Care
After fertilization, the female may prepare a protected nest site in soil or between rocks.
Some species can lay up to around 300 eggs.
In many cases, the female guards the eggs for a period, and early juveniles may remain near the mother briefly after hatching.
Examples of Myriapods
Below is a list of myriapod examples (primarily centipede species names) to illustrate the diversity you can find across different regions:
Cormocephalus venezuelianus
Otostigmus carbonelli
Rhysida caripensis
Cryptops venezuelae
Newportia andina
Newportia autanensis
Newportia guaiquinimensis
Newportia pilosa
Ribautia tropica
Ribautia vivasberthier
Geophilus venezuelae
Koinethmus guanereus
Sphendononema guildingii
Notiphilides maximiliani
Titanophilus hasei
Cerethmus naiquatanus
