Arthropoda Class-Chilopoda and Diplomoda, Biology tutorial

Arthropoda Class - Chilopoda and Diplomoda

General Characteristics of Chilopoda and Diplopoda:

Some characteristics of class Chilopoda and Diplopoda are given below.

i) They are essentially terrestrial

ii) Have clearly stated head.

iii) Other body segments are all similar.

iv) Contain 1 pair of antennae

v) Contain 1 pair of mouth parts or jaws.

vi) The eyes may be plain, complex or not present.

vii) There are several identical legs, the pair in each segment in Chilopoda and 2 pairs in every segment in Diplopoda.

viii) There are no larval forms.

ix) The gaseous exchange is by trachea.

x) Chilopodans are mostly carnivorous whereas Diplopodans are mostly herbivorous.

Examples are:

Chilopoda - Lulus (Millipede)

Diplopoda - Lithobuis (Centipede).

The major differences between two classes are given below:

The first is fact that as centipedes contain 1 pair of appendages per segment, millipede has 2. Though both have numerous appendages. The second dissimilarity is that centipedes are carnivores while millipedes are herbivores.


The body of millipede is more cylindrical. Millipedes live in litters of leaves or just under soil. They feed on dead leaves or dead plant material. They are helpful as they help to break down dead plant material to humus. Millipedes are generally limited to damp places where they consume organic matter. In fall, they may turn out to be the nuisance as they travel away from feeding areas and occupy homes. As they crawl along ground, they are generally found in lower floors and basements. Once inside home, they generally die because of aridity, though in moist basements, they can live longer.


The bodies of centipedes are flat and generally have between 15 to 20 segments. This number is less than that of millipede. Centipedes move extremely fast. They chase their food. They feed on insects, spiders, and worms which they paralyze with bite and venomous claw. Even to humans, their bite is painful. Adult centipedes bury in wet dark and quiet areas in winter. They lay eggs in wet soil in summer or spring. As centipedes turn into adults, they grow the entire set of legs and additional segments. Most centipedes live for more than year and some up to 6 years. Centipedes may come in houses and buildings, but they don't roam in daytime. They bury in moist areas around closets, basements, bathrooms and other sites usually infested by pests.

Common features of Arachnida:

The arachnids are terrestrial. They have the cephalo thorax. The thorax is divided from abdomen by the narrow waist-like constriction. They don't have antennae. They don't contain true mouth parts. 1 pair of appendages is utilized for capturing prey (chelicerae or pincers) while other is utilized as the sensory palp. They only include simple eyes. They have no compound eyes. There are 4 pairs of working legs. There are no larval forms gaseous exchange occurs by "lungs" books (abdominal respiratory books made of several leaves) or trachea. Mites, ticks and scorpion belong to the group. In place of the terminal spine, scorpion has at the end of the abdomen, sting - its principal organ of offense. Most arachnids can just consume liquid food, not solid food, so they squirt digestive chemicals in prey and suck out juice.

Spiders and Scorpions:

Spiders are in different ways more specialized than scorpions although they have much in common. There are the set of 8 simple eyes on carapace covering cephalothorax. It has pointed chelicerae and have poison gland. Chelicerae are for catching prey. Like in scorpion, its first pair of working legs is altered as sensory pedipalps for holding and influence prey. Remaining 4 pairs of walking legs have clawed tips. There 3 pairs of spinnerets on abdomen that doesn't demonstrate any signal of segmentation. Spinnerets are small appendages at posterior end of abdomen specialized for spinning silk. Different types of glands make silk as liquid that later solidifies when it comes in contact with air. Every gland makes its own kind of silk used for the particular reason.

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