River Piranha Plant
From the Super Mario Wiki
River Piranha Plants are sub-species of Piranha Plants that appear in New Super Mario Bros. Wii and New Super Mario Bros. U. They appear in World 5-1 as common enemies in New Super Mario Bros. Wii. They also appear in Seesaw Bridge in New Super Mario Bros. U. As their name implies, they live in rivers. When Mario is not around, they blow green spike balls like a Ptooie's method of attacking. When Mario approaches, however, they suck in and bring the spike ball to their lips and slowly blow it upwards to attack. Just like regular Piranha Plants, they can be defeated with fireballs or a Starman. The spike ball itself can be taken out with a shell or the Starman, after which the River Piranha Plant will sweat and panic in place, unable to do anything.
In New Super Luigi U, they appear in quicksand as well as water. Their behavior does not change.
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