The Hydroid Medusas were large behemoths designed for underwater combat. They had on-board power plants and multiple electrified tentacles that could kill any biological being upon contact. However, they were at a risk of being short-circuited if near any electrical source.
Commander Riff Tamson used a number of units in his conquest of the planet Dac for the Confederacy of Independent Systems, dropped onto the planet via Separatist landing craft. Invulnerable to blaster bolts and even lightsabers they proved a formidable opponent and forced the Republic and Mon Calamari resistance fighters to retreat with some casualties. Later Republic reinforcements in the form of the Gungan Grand Army arrived, with their boomas temporarily short-circuiting some of the Hydroid Medusas, though a fair number of them remained dispersed in the oceans after the Gungan army was captured. The battle was eventually won by the Republic.
- Star Wars: The Clone Wars – "Water War" (First appearance)
- Star Wars: Clone Wars Adventures – "Aquatic Assault"
- Star Wars: The Clone Wars – "Gungan Attack"
- Star Wars: The Clone Wars – "Prisoners"
- Star Wars: The Clone Wars Comic UK 6.26
- "Blood-Feud: Warriors of the Deep!"—Star Wars Insider 129
- Star Wars: The Clone Wars Comic UK 6.32
- Star Wars: The Clone Wars: Episode Guide
- Star Wars: The Clone Wars Comic UK 6.50
- Star Wars: The Clone Wars Magazine 20
- The Official Star Wars Fact File Part 8 (LEE1-2, Lee-Char)