Although both insects and arachnid are arthropods still they have some key anatomical differences that make them distinctive from each other.
Arthropoda or arthropod is a phylum that consists of invertebrates with jointed appendages or legs. Arthropods are triploblastic, haemocoelomic animals. All classes of arthropods consist of a segmented body with a head, thorax, and abdomen. They also consist of a chitinous exoskeleton. They are the most successful phylum in the earth.
Arachnids are a class of joint-legged invertebrate animals in the subphylum Chelicerata and Insects or Insecta (from Latin insectum) are hexapod invertebrates and the largest group within the arthropod phylum.
Both insects and arachnids are mainly terrestrial animals. Some of them live as parasites. The main difference between insects and arachnids is that insects have six legs and up to four wings whereas arachnids have eight legs.
The body of an insect is comprised of three segments: the head, thorax, and abdomen. The body of an arachnid is comprised of two segments: the cephalothorax and the abdomen.
- Insects have six legs; arachnids have eight legs.
- Insects have antennae; arachnids do not.
- Insects have mandibles; arachnids have chelicerae.
- Insects have compound eyes; arachnids have simple eyes.
- Many insects have wings; no arachnid has wings.
- Insects undergo some form of metamorphosis