There are 13,000 species of arthropod in Myriapoda. Millipedes and centipedes belong to this group. They are ground living creatures. “Myriad” in their name means 10,000 legs. Myriapods can have more than 750 legs or less than 10 legs. These legs range in size from nearly microscopic to 30cm in length. Many of them love the humid environments, and they can be found in soils, in leaf litters, or under stones and wood. Many of them are able to produce disgusting compounds to keep themselves away from their predators.
They have a single pair of antennae and a pair of simple eyes. Their mouth is under their head, There is a pair of jaw inside their mouth. They breathe through the small holes on their skin like the insects.
The female lays her eggs and the young will have only a few segments. They may even have as few as 3 pairs of legs. The young will have extra segments and legs as they repeatedly moult themselves until they become an adult.
There are 4 groups of myriapods. They ar Symphyla. Pauropoda, Chilopoda and Diplopoda. Chilopoda includes the true centipedes. They are quick moving creatures. They hunt at night. There are around 3,300 species of centipedes. They can be less than half an inch in length like the Nannarup hoffmani to more than 12 inches (30cm) in length like the Giant Scolopendra gigantea. They have only one pair of legs on each segment. They are predators. The first pair of appendages on the trunk are their poisonous claws which they use to kill their prey. Their bite can cause pain to a human.
There are about 200 species if Symphylans. They look like centipedes but they are much smaller and translucent. They live in the soil. The young ones have 6 pairs of legs. As they moult to an adult, an additional pair of legs will grow on each moult. So, when they are an adult they have 12 pairs of legs.
Pauropoda is another small group of small myriapods. They are about 0.5-2.0mm long and they live in the soil too. They can be found in all continents except for Antarctica. There are more than 700 species of them.
Diplopoda includes the millipedes. The Latin word milli means thousand and ped means foot. So, millipedes are creatures with many foot. Most millipedes are slower than centipedes. They feed on leaf litter and dead organisms. They are identified by the fusion of each pair of body segments into a single unit. Therefore, they look as if they are having 2 pairs of legs per segment. There are about 8000 species of them. The Illacme plenipes millipede has the most legs of any animals. It has over 750 legs. Millipedes will normally have about 36 to 400 legs. Pill millipedes are much shorter and are able to roll into a ball like pillbugs.