Valentines Day is here and this month on Naked Oceans we reveal some of the unusual mating habits of ocean animals. How do they track down a mate in the enormous oceans? What happens if they are stuck firmly in place on the sea floor? And what does all this mean for our efforts to protect ocean life?

We find out what happens when the animals that build coral reefs take part in a huge, synchronised love-in. We call in on the Cayman Islands to discover how the spawning habits of many fish put them in grave danger of being overfished. And we find out how jellyfish make more jellyfish and whether these prolific beasties really are going to take over the oceans.

Plus, we find out from a gender-bending Critter of the Month what life is like being both a male then female.