The centipedes and millipedes possess uniramous (unbranched) appendages, and are characterized by a number of body segments, each with walking legs.

The two main groups of myriapods are the centipedes (Class Chilopoda) and the millipedes (Class Diplopoda). Both prefer moist habitats and are mainly active at night. During the day they are usually found under rocks, logs, etc. They and other myriapods are characterized by a head region followed by an elongate trunk of many segments. Centipedes are carnivores characterized by one pair legs on each segment behind the head. Despite the difficultly of coordinating their walking legs, centipedes are able to move quite swiftly. The first pair of legs (maxillipeds) is modified into fangs which are used for injecting venom into prey. Most centipedes feed on other arthropods but some of the larger ones are known to eat mice, frogs, and snakes. Millipedes, on the other hand, are generally herbivores. They are not as agile as centipedes and most crawl fairly slowly. Many, however, are protected by poisonous secretions, and some even produce hydrogen cyanide. Thus, few animals eat millipedes. The distinguishing feature of the millipedes is the presence of diplosegments (doubled trunk segments) resulting from the fusion of adjacent segments giving the appearance of two pairs of legs per segment for all except the anterior four trunk segments.

The last subphylum of arthropods is the Hexapoda, which includes the insects and their more primitive relatives. Because of the enormous diversity and importance of insects in all facets of biology, we’ve reserved a separate lab for them.