Fig. 3. Method used to determine the freezing resistance of P. antarcticum larvae. An individual larva was placed in a drop of seawater on a solid 6 mmx6 mm aluminum slide (AS), which was mounted on the thermoelectric cooling module (CS) of the Clifton nanoliter osmometer. A needle (ND) was cooled in liquid nitrogen and used to initiate ice crystal (IC) growth in the seawater surrounding the larva. Cooling is accomplished with stacked Peltier devices (PD) mounted on a water-cooled brass heat sink (HS). The stage temperature is controlled via a negative-feedback mechanism using a micro-thermistor (MT) mounted within the stage, and a separate temperature control module, connected to the cooling module by a cable (CC).