Description: Zoothamnium niveum is a colonial Protist that reaches 2 - 3 mm in height. Individual zooids have an inverted bell shape and measure approximately 120um in height. The contractile vacuole is located below the peristomial lip. Zooids are attached to a common stalk, which is contractile and branching. A continuous myoneme is centrally located in the stalk, allowing zooids in the colony to contract together in a zig-zag fashion, rather than spirally as occurs in other members of this family (i.e., Vorticella spp.). The myoneme is not sinusoidal when the colony is relaxed.Z. niveum is typically found in mangrove peat and wood debris. It thrives in the anoxic boundary layer of sediments where it consumes sulfur bacteria.
Report by: K. Hill, Smithsonian Marine Station