The GUARD1 system is a low-cost stand-alone instrument for underwater image acquisition and recognition of gelatinous zooplankton. It is designed for installation and autonomous operation on different platforms (e.g. fixed, towed, mobile). Its low cost, small size and low power consumption coupled with a long-life battery pack equipment, make it an ideal system for long lasting deployments. The system is fully programmable and reconfigurable via software for being effective in a large range of applications.