In their invaded range, NZMS are asexual, and populations are nearly entirely comprised of females. As such, only one female is needed to establish an invasive population, which is then entirely clonal and polyploid (Ponder 1988, Jokela et al. 1997, Proctor et al. 2007). Asexual NZMS are parthenogenetic and ovoviviparous– they develop eggs that do not require fertilization in a brood pouch until they are mobile (Jokela et al. 1997). Broods often contain 20–30 young, but the gestation period, number of young, number of broods, and growth rate of young are dependent on environmental conditions. Under favorable conditions, NZMS can breed year-round (Verhaegen et al. 2018).
While their low genetic diversity resulting from their parthenogenetic nature limits their evolution capabilities, the most invasive clones tend to have relatively high phenotypic plasticity and a naturally broad environmental tolerance; this allows them to be successful invaders (Drown et al. 2011, Hoy et al 2012). They can survive in both lentic and lotic habitats, including brackish and freshwater, and tolerate a relatively wide range of temperatures, salinities, and water flow rates (Costil et al. 2001, Proctor et al. 2007, Drown et al. 2011).