A Bloggling is a species found in the GameCube video game Metroid Prime 2: Echoes. They are found only in water, such as in the Hydrodynamo Station (only after you release the first lock), among other places. They're the offspring of a Blogg, and thus are much smaller and weaker.
Generally they won't ram into Samus as their older, stronger parents do, and they are also relatively easy to kill. Because they aren't strong, they apparently must rely on their agility and speed once attacked.