9.12: Centipedes and Millipedes
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How many legs does a centipede have?
You might think that centipedes have a hundred legs. But many species of centipedes don't have quite that many legs! The common house centipide has only 15 pairs of legs.
Centipededs and Millipedes
Centipedes and millipedes belong to the subphylum Myriapoda, which contains 13,000 species. They all live on land, which makes sense as all those legs are more adapted to a terrestrial lifestyle, as opposed to an aquatic lifestyle.
The Myriapoda are divided among four classes: (1) Chilopoda (centipedes), (2) Diplopoda (millipedes), (3) Symphyla (symphylans), and (4) Pauropoda (pauropods). They range from having over 750 legs to having fewer than ten legs. They have a single pair of antennae and simple eyes.
Myriapoda are mostly found in moist forests, where they help to break down decaying plant material. A few live in grasslands, semi-arid habitats, or even deserts. Most myriapods are decomposers, with the majority herbivores breaking down decaying plant material, but centipedes are nighttime predators. Centipedes roam around looking for small animals to bite and eat; their prey includes insects, spiders, and other small invertebrates. If the centipede is large enough, it will even attack small vertebrates, like lizards. Although not generally considered dangerous to humans, many from this group can cause temporary blistering and discoloration of the skin.
Centipedes ("hundred feet") (Figure below) are fast, predatory carnivores, and venomous. There are around 3,300 described species, ranging from one tiny species (less than half an inch in length) to one giant species (the Peruvian giant yellow-leg centipede or Amazonian giant centipede), which may grow larger than 12 inches. This giant centipede has been known to attack, kill and eat much larger animals, including tarantulas. Centipedes have one pair of legs per body segment, with the first pair of legs behind the head modified into a pair of fangs containing a poison gland. Many centipedes also guard their eggs and young by curling around them.
Most millipedes are slower than centipedes and feed on leaf litter and loose organic material. They can be distinguished from centipedes by looking at the number of legs per body segment. Millipedes have two pairs of legs per body segment, while centipedes have a single pair of legs per body segment. Millipedes protect their eggs from predators by using a nest of hard soil. Millipedes are not poisonous. They lack the pair of fangs containing a poison gland that centipedes have.
The third class, Symphyla, contains 200 species. Symphylans resemble centipedes but are smaller and translucent. These arthropods have an elongated body, with three pairs of thoracic legs and about nine pairs of abdominal legs, giving this class 12 pairs total. Many spend their lives in soil feeding on plant roots, but some do live in trees.
The pauropods are typically 0.5-2.0 mm long and live on all continents except Antarctica. They are usually found in soil, leaf litter, or other moist places. They feed on fungi and decaying organic matter, and are essentially harmless. Adult pauropods have 11 or 12 body segments and 9-11 pairs of legs. They also possess unique forked antennae and a distinctive pattern of movement characterized by rapid burst of movement and frequent abrupt changes in direction. Over 700 species have been described, and they are believed to be closely related to millipedes.
- Myriapoda are usually found in moist forests, where they break down decaying plant material.
- Millipedes have two pairs of legs per body segment, while centipedes have a single pair of legs per body segment.
Use the resources below to answer the questions that follow.
Explore More I
- Where do centipedes live?
- What and how do centipedes eat?
- Do centipedes have 100 legs?
Explore More II
- What is the diet of most millipedes?
- In what kind of habitats are millipedes found?
- What is interesting about the legs of a newly hatched millipede?
Explore More III
- Arthropod Animation: Millipede Breathing Tubes at vimeo.com/37410640
- How do millipedes draw air into their body?
- Where do centipedes and millipedes generally live?
- List two ways centipedes are different from millipedes.
- What are the differences between the legs of a centipede and millipede.
- What are the main food sources of centipedes?