Complex sentence: Their length varies between 20 cm and 75 cm ("Aplysia vaccaria"), and they can weigh well over 2 kg. They are cosmopolitan and found in temperate and tropical seas, inhabiting shallow coastal areas and sheltered bays, thick with vegetation.
Split into simpler sentences: Their length varies between 20 cm and 75 cm ("Aplysia vaccaria"). They inhabit shallow coastal areas and sheltered bays, thick with vegetation.