Who can forget the most iconic cinematic fish family of all, Nemo and his dad? On its surface, the movie is an adventure and survival tale with the undertones of a single parent who'll do anything to save his child after already losing his mate. But if you know anything about the reproductive roles of clownfish, well, let's just say that any future sequel to "Finding Nemo" might include a somewhat awkward heart-to-heart between father and son. You see, clownfish -- or anenomefish -- are one of the most notable examples of sequential hermaphrodites in the ocean.
Clownfish live in the shelter of an anemone, and they never stray very far from their homes. Compared to other fish that travel far and wide, the limited mobility of the clownfish could put a damper on mating. But because clownfish can change sex, they're able to keep their species going. When a male clownfish pairs with another male clownfish (all clownfish are born male), one of them will simply turn female so that the two can spawn. When the female dies, the largest male in the area will take her place by turning into a female. Then, one of the more dominant nonmating males will begin mating with her. This subset of sequential hermaphrodites is known as protandrous hermaphrodites; ones that shift from female to male are known as protogynous hermaphrodites.
Nature offers many other species that can swing in either gender direction for the sake of survival, from plants to sea life and even on land. In fact, this has led some Yale scientists to wonder why hermaphroditism doesn't occur more frequently. One of the reasons being explored involves the amount of time it takes to change genders; some specimens can take up to 30 percent of their lifetime to complete the transformation [source: Science Daily]. But even those species still reproduce in numbers sufficient enough to maintain their populations.
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