The classification of crustaceans is complex and can vary depending on the source. However, the most widely accepted classification recognizes eight major subclasses of Crustacea:

1. Remipedia: Blind, subterranean crustaceans.

2. Cephalocarida: Small, primitive crustaceans.

3. Branchiopoda: Diverse group including fairy shrimp, brine shrimp, and tadpole shrimp.

4. Maxillopoda: Includes barnacles, copepods, and other diverse groups.

5. Ostracoda: Tiny crustaceans enclosed in a bivalve shell.

6. Malacostraca: The largest subclass, including crabs, lobsters, shrimps, crayfish, and isopods.

7. Mystacocarida: Small, interstitial crustaceans.

8. Pentastomida: Parasitic crustaceans.

Note: Some sources may include the extinct class †Phyllocarida or combine some of the subclasses into larger groups.