Myriapods (Subphylum Myriapoda) are many-legged terrestrial arthropods that include centipedes, millipedes, and two small groups of relatives, the pauropods and symphylans. Unlike most other arthropods, such as insects (Class Insecta) and spiders (Class Arachnida) that

have 3 or 4 pairs of legs respectively, myriapods usually have more than 10 pairs of legs. Surprisingly, some millipede species, such as Illacme plenipes, found in northern California, has up to 750 legs in its less than 3-cm-long body, setting the world record for the leggiest creature on earth.

Centipedes and millipedes look similar to each other, having many legs on an elongated body. However, millipedes (Class Diplopoda) have two pairs of legs per body segment, while centipedes (Class Chilopoda) have only one pair of legs per segment. Also, the length of each leg is longer in centipedes than in millipedes. The body of centipedes is more flattened, compared to millipedes, which have a cylindrical body, although some millipedes are somewhat flattened. Both centipedes and millipedes can be easily found under rocks, logs, and dead leaves, and can be collected by using pitfall traps, sifters,  and Berlese funnels.

Centipedes are fast-moving predators, hunting small animals at night. Most species of centipedes have venom in their pincer-like appendage originated from the first pair of limbs, and it can be hazardous to humans. The world’s largest centipede, Scolopendra gigantea, grows over 30 cm in length, and this species is known to hunt frogs, lizards, and even small birds and bats. However, all Canadian species are quite small and harmless to people, feeding mainly on small invertebrates. Centipedes generally do not copulate, instead, adult males leave a spermatophore on the ground for females to find and engulf it for reproduction.

Millipedes are slow-moving decomposers, generally eating decaying plant material. However, some millipedes found in greenhouses often cause serious damage to plant seedlings. Many species of millipedes have defensive glands along the sides of their bodies to repel other predators. Millipedes also can curl their body into a coil to protect their relatively soft underside when disturbed. Most millipedes engage in copulation, although some species have an indirect mating system. In the direct mating system, males can transfer sperm to the female through gonopods, modified legs located in the seventh segment for most species.

Pauropods (Class Pauropoda) and symphylans (Class Symphyla) are inconspicuous and tiny groups of myriapods that live in the soil and leaf litter. Pauropods have forked antennae, while symphylans have long bead- like antennae. Members of both groups have no eyes, and body colour is often translucent.

In Canada, a total of 145 species of myriapods have been recorded. In the NWT, however, only a few species of centipedes have been documented and no species have been identified for the rest of the three classes. Considering such serious knowledge gaps on diversity and ecology of myriapods in the NWT, sampling and studying these many-legged creatures can greatly overcome the current situation. Myriapods are most common in leaf litters and soils in wet forests. Thus, there is huge potential to discover new myriapod species by searching under rocks, logs, and dead leaves, using the above-mentioned trapping methods.