96 books • 15 series
Polar Bears (X-Books: Marine Mammals)
Elephant Seals (X-Books: Marine Mammals)
Walruses (X-Books: Marine Mammals)
Unicorns (X-Books: Mythical Creatures) (Amazing Mysteries)
Blue Whales (X-Books: Marine Mammals)
Sea Otters (X-Books: Marine Mammals)
Amazing Mysteries: Dragons (Amazing Mysteries) (X-Books: Mythical Creatures)
Sea Lions (X-Books: Marine Mammals)
Mermaids (X-Books: Mythical Creatures) (Amazing Mysteries)
Vampires (X-Books: Mythical Creatures) (Amazing Mysteries)
Iguanas (X-Books: Reptiles)
Geckos (X-Books: Reptiles)
Chameleons (X-Books: Reptiles)
Sea Turtles (X-Books: Reptiles)
Crocodiles (X-Books: Reptiles)
Monitor Lizards (X-Books: Reptiles)
Moths (X-Books: Insects)
Cicadas (X-Books: Insects)
Beetles (X-Books: Insects)
Ants (X-Books: Insects)
Stick Insects (X-Books: Insects)
Dragonflies (X-Books: Insects)
Wasps (X-Books: Insects)
Crickets (X-Books: Insects)