Creatures that spread their gametes in the sea are gambling with high stakes: get it wrong and your genes are heading towards a dead-end in the evolutionary tree. This is a strong incentive to develop eggs with a high chance of getting fertilized, but only if the advantages come at a realistic cost. One frequently used low cost solution to improving an egg's fertilization odds is to surround the tiny gamete with a gel coat that interacts with sperm in a variety of chemical and physical ways. Up until now,most people had analysed the gel from a chemical perspective, but Robert Podolsky wanted to know how important the gel's size was to an egg's chances of survival. Weighing up the gel's advantages to sand dollar eggs from this alternative perspective, he discovered that 75% of that advantage comes simply from the egg's increased size and buoyancy(p. 1657).
Sand...
