cristispira cristispira cristispira is a genus of bacteria of the spirochete phylum. they are known as large spirochetes. they are characterized by the host species in which they reside. they are known as harmless parasites of freshwater and marine molluscs and gastropods. they have unusually large number of periplasmic flagella. cristispira scientific classification domain: bacteria phylum: spirochaetota class: spirochaetia order: spirochaetales family: borreliaceae genus: cristispiragross 1910 type species "cristispira pectinis"gross 1910 species "c. anodontae" keysselitz 1906 "c. balbiani" (certes 1882) certes 1882 "c. interrogationis" gross 1910 c. pectinis gross 1910 "c. pinnae" gonder 1908) gross 1910 morphology they are differentiated from other spirochetes by the presence of a crestlike structure called the crista. their cell bodies are flexible. the cell diameter is 28 to 120 micrometers. they are actively motile.