Final answer:
The major classes within the subphylum Chelicerata are Arachnida, Merostomata, and Pycnogonida.
Step-by-step explanation:
The major classes within the subphylum Chelicerata are:
- Arachnida: This class includes animals such as spiders, scorpions, ticks, and mites. They are mainly terrestrial but can also be found in freshwater and marine environments.
- Merostomata: This class includes animals such as horseshoe crabs. They are marine arthropods that have been around for millions of years.
- Pycnogonida: This class includes animals known as sea spiders. They are marine arthropods with long legs that are adapted to their environment.