"Porifera Elektricus" is a species of sponge native to Little Lake known for their strong electrical current.
As a species, they apparently only become active when the sun sets, as mentioned by Dr. Ruffalo. When active, they continuity electrocute the water, frying everything that enters the lake, even canoes.
During "Big Trouble at Little Lake", Dr. Ruffalo warns Donald Duck of the electric sponges and how they emit a strong electronic current. Donald doesn't believe Ruffalo at first, but after witnessing a bird getting fried when landing in the water, Donald quickly becomes fearful of the species. When Huey, Dewey and Louie procure a canoe wrapped in life jackets, Donald attempts to use that to escape from the lake, but the sponges electrocute it as well.