Biology: Centipedes and Millipedes

Study Notes

Centipedes are elongated, segmented creatures with one pair of legs per body segment.
All centipedes are venomous and can inflict painful stings.
Centipedes belong to the kingdom Animalia, subkingdom Metazoa, phylum Arthropoda, and class Chilopoda.
Millipedes have two pairs of jointed legs on most body segments.
Most millipedes have elongated, cylindrical or flattened bodies with more than 20 segments.
Millipedes are generally harmless to humans, although some can become household or garden pests.

Insects have all the characteristics of Arthropods and three body regions: head, thorax, and abdomen.
Insects also have three pairs of legs, one pair of antennae, and bilateral symmetry.
Insects belong to the class Insecta, which is distinct from other classes of Arthropods like Diplopoda (millipedes) and Chilopoda (centipedes).

All Arthropods have a chitinous exoskeleton.
All Arthropods have bilateral symmetry.
All Arthropods have jointed appendages.
All Arthropods have segmented bodies.
All Arthropods have a tubular digestive tract, a dorsal tubular circulatory system, and a ventral nervous system.

The Phylum Arthropoda includes Chelicerata (e.g., scorpions, spiders, ticks) and Mandibulata (e.g., lobsters, insects).
Chelicerata have mouthparts outside the head, two body regions, no antennae, and four pairs of walking legs.
Mandibulata include lobsters, which have long bodies with muscular tails, and live in crevices or burrows on the sea floor.

Exoskeleton provides support, allowing for large open spaces.
Exoskeleton provides muscle attachment points.
Exoskeleton provides a body covering and good protection.
Exoskeleton provides water conservation, which is essential for insects.
Exoskeleton provides growth restrictions, which is a problem.
Exoskeleton provides good mechanical advantage, enabling insects to perform impressive feats.

Insect body regions are called Tagma, which are groups of segments that function together to perform a general task.
Head Tagma: perception, food intake.
Thorax Tagma: locomotion, food processing.
Abdomen Tagma: reproduction, excretion.

Antenna: odor receptors, used for insect identification.
Compound eyes: composed of many individual eye units called Ommatidia.
Simple eyes: composed of 1 unit, often arranged in the shape of a triangle on adult insects.