Birth control for breakfast, anyone?

Consider it further testament that there are no free lunches in nature. Small crustaceans called copepods devour diatoms when the microscopic algae bloom in the ocean, but the eggs produced by these satiated copepods hatch less than a quarter of the time. That's a success rate far below the normal 90 percent or so. The reason for the falloff, explain Italian researchers in the Nov. 11 NATURE, is that blooming diatoms produce substances that amount to copepod birth-control pills.

The substances, compounds known as aldehydes, were isolated from diatoms by Antonio Miralto of the Anton Dohrn Zoological Station in Naples, Italy, and his colleagues. The aldehydes seem to inhibit cell proliferation within copepod embryos. The researchers note that copepods have evolved defenses against algae-derived neurotoxins that directly kill them, so it's surprising that the crustaceans haven't kept ahead of toxins that affect their reproduction. "Possibly, the ability to cope with straightforward toxins evolves faster than the response to insidious ones," the investigators speculate.