Abstract: Provided herein are devices, systems and methods for separating age and size matched nematodes from a mixed size population of nematodes and/or debris. The device and system use a filter membrane with a defined pore size located between an upper housing with a first chamber adapted to receive a liquid sample comprising the mixed size population nematodes and a lower housing with a second chamber. Use of the system, along with a sample vessel, provide the user a method for efficiently and effectively isolating an age and size synchronized population of nematodes.