This phenomenon is the slow block to polyspermy.

The fast block is an electrical block to polyspermy.

Decreasing the incidence of polyspermy (e.g. some mammals such as pigs).

Triploidy, usually due to polyspermy, occurs in about 2-3% of all human pregnancies and 15% of miscarriages.

In sea urchins, the block to polyspermy comes from two mechanisms: the fast block and the slow block.

According to the Jerusalem Talmud Goliath was born by polyspermy, and had about one hundred fathers.

The slow block to polyspermy in the sea urchin is mediated by the PIP secondary messenger system.

In the slow block to polyspermy, the cortical granules released from the ovum are deposited in the perivitelline space.

On the one hand, polyspermy creates inviable zygotes and lowers female fitness, but on the other, defenses may prevent fertilization altogether.

In species without an electrical block, polyspermy is usually prevented by secretion of materials that establish a mechanical barrier to polyspermy.

Fertilization in Fishes and the Problem of Polyspermy, Israel Program for Scientific Translations, Jerusalem.

Nevertheless, polyspermy preventing mechanisms are essential in mammals; a secretion reaction, the "cortical reaction" modifies the extracellular coat of the egg (the zona pellucida), and additional mechanisms that are not well understood modify the egg's plasma membrane.