If you are referring to the flash/mini-game Froggy Castle (an elevator-climbing puzzle game), please see the at the end.
The frog was not defenseless. The game introduced a mechanic where the protagonist could use his tongue or collected items to dispatch enemies. The enemies ranged from insects to larger castle guardians. The challenge came from the limited space. Players often had to eliminate enemies to clear a path, but doing so required exposing the frog to risk. Health was a Froggy Castle 1
Each of the 20+ levels (spread across 6 floors) introduces new ways to die: If you are referring to the flash/mini-game Froggy
: When a frog is hit, it splits into two smaller frogs. This process continues until the smallest frogs are destroyed. Danger Zones Froggy Castle 1