Centipede vs Millipede: What's The Difference?
- bioworld090
- Feb 27, 2023
- 4 min read
Updated: Mar 5, 2023
Centipedes and millipedes are arthropods that share the same subphylum, Myriapoda. Other than sharing the same subphylum, they also show some other commonalities such as having many legs, a segmented body, and antennae on the head. These common features make it difficult for many people to distinguish between them. So, below are some differences between centipedes and millipedes that would help you to correctly distinguish between them.
LEGS
The first thing that comes to mind upon hearing the words "centipede" and "millipede" is probably the number of legs. In fact, the names "centipede" and "millipede" mean "hundred feet" and "thousand feet". However, no centipede has exactly 100 legs, and only one species of millipede, Eumillipes persephone, has more than 1000 legs.
Centipedes have one pair of legs per segment and their legs are attached to the side of their body. Millipedes, on the other hand, have two pairs of legs per body segment, and their legs are attached to the underside of their body.
ULTIMATE LEGS
The last pair of legs is the longest pair of legs in centipedes and serve different functions. This pair of legs is known as the ultimate legs. The ultimate legs vary in their morphology and can be elongated, pincer-like, leaf-like, etc.
While the term "ultimate legs" has a "leg" in it, it seems to play no role in walking. Instead, they have various other functions depending upon the species.
The ultimate legs play a role in:
LOCOMOTION
As already stated, the ultimate legs do not play a role in walking. However, they do play a role in locomotion by balancing and stabilizing the body of centipedes while running.
ANCHORAGE
Some centipedes like those that belong to the genus Scolopendra can use their ultimate legs to anchor themselves to some kind of substrate.
An example of this is Scolopendra gigantea, which clings to the caves and swings the rest of its body to hunt bats.
DEFENSE
Several species of centipedes use their ultimate legs for defense. When threatened, they raise their ultimate legs in the air and spread them to dissuade the attacker.
Centipedes such as some of those that belong to the order Scolopendromorpha also use their ultimate legs for defense but rather than spreading and raising them in the air, they autotomize or lose their ultimate legs to distract the attacker and escape. The ultimate legs of some species, after being autotomized, can wriggle, and in others, they can stridulate or produce sound.
The ultimate legs also play a role in attack and mating.
While centipedes possess ultimate legs that serve different purposes, millipedes lack these structures.
ANTENNAE
Centipedes have long antennae while millipedes have short antennae.
SHAPE
Centipedes are generally flat-bodied while millipedes generally have a cylindrical body.
DIET
Centipedes are venomous, solitary, predatory, carnivorous myriapods that hunt their prey by injecting venom through their forcipules (modified front legs or maxillipeds). They then use their mandibles to consume the prey. The prey animals of centipedes include snails, cockroaches, moths, spiders, earthworms, silverfish, crickets, and even other small centipedes. Scolopendra gigantea, the largest centipede, consumes small birds, frogs, mice, and bats.
Millipedes are primarily detritivores and feed mainly on decaying plant materials. There are a few species of millipedes that are carnivores such as those of the orders Callipodida and Chordeumatida which feed on insects, centipedes, earthworms, or snails. The millipedes in the order Callipodida especially the species Apfelbeckia lendenfeldii, Callipus foetidissimus, and Abacion magnum are even known to exhibit cannibalism.
There are others such as those of the orders Polyxenida and Platydesmida that thrive on algae and fungi respectively.
SPEED
Centipedes are often seen as creepy, crawling insects but they are not just crawlers. They are also fast runners and can reach speeds of up to 16 inch/s.
Millipedes, unlike their fast-running centipede relatives, are slow-moving.
RESPONSE TO THREAT
Centipedes respond in various ways to a threat. The usual response to a threat is running away from the danger as they are pretty fast runners. The next response to a threat is biting using their venomous forcipules. The last way centipedes respond to a threat is by using their ultimate legs. They can raise and display their ultimate legs to warn predators, pinch with their ultimate legs or lose their ultimate legs when grabbed by them.
Millipedes respond completely differently when threatened. Unlike centipedes, they do not have venom or biting and pinching structures. They are also slow movers, and they can't outrun the threat. So, what they do is coil their body in a spiral and secrete harmful substances.
There is an order of millipedes, the Polyxenida, that lack both hard exoskeleton and toxins. Instead, they possess hair-like structures at their rear end. These hair-like structures are known as caudal tufts and are detachable. When threatened, they can use these caudal tufts to entangle predators like ants and spiders.
The picture above shows the millipede, Polyxenus lagurus, a member of the order Polyxenida.
SPIRACLES
Spiracles are small openings or holes on the surface of the body of animals like insects, myriapods, worms, etc. These small openings help the animal to breathe by allowing the entry of air into the trachea.
Centipedes possess spiracles on the sides or top of their body while millipedes bear spiracles on the underside of their body.
MALPHIGIAN TUBULES
Malphigian tubules are tube-like excretory and osmoregulatory structures that absorb water, wastes, and solutes from hemolymph (fluid in arthropods that is similar to the blood of vertebrates). The collected waste is then emptied into the alimentary canal between the midgut and hindgut where the malphigian tubules open.
Centipedes have only one pair of these excretory and osmoregulatory malphigian tubules while millipedes have two pairs of malphigian tubules.
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