Define Subphylum Chelicerata - classes Arachinda AM merostomata?

The subphylum Chelicerata includes familiar horse shoe crab, spiders, scorpions, ticks and mites.

1. Body consists of an anterior prosoma and a posterior opisthosotna.

2. Prosoma bears the appendages involved in feedings and locomotion. Opistliosoma may have exterior segmentation but appendages are either absent or considerably reduced.

3. Their main appendages are clielicerae and pedipalpi.

4. Antennae and mandibles are absent.

5. These are the first land animals in evolution of arthropods which have successfully colonised the terrestrial environment.