Mass cultivation of marine copepods as live feed requires predictable and uniform production of a standard product for the end users, the hatcheries. A previously undescribed large egg type, measuring a mean diameter of 106.5 μm, was characterized and compared to normal eggs (82.3 μm) from a continuous culture of Acartia tonsa. The large egg type was significantly larger than the normal eggs, and only 1 large out of approximately 100 000 normal-sized eggs was found