Choosy Much? Female Fish Can Pick The Father of Their Offspring

Scientists have recently discovered that female ocellated wrasses, Symphodus ocellatus, have learned a trick to outwit their sexual partners -- learning how to choose who will father their offsprings.

According to the study published in the journal Nature Communications, female ocellates wrasses actually prefer males who are armed with good parental care, meaning they build algae nests and are committed to take care of the eggs as they hatch.

Marine animals usually reproduce by spawning. During which, the female fish will release the eggs into the water or the algal bed and at the same time, the male fish will release sperm to fertilize the eggs. Usually, during this process, "sneaky" fish enter the scene. These fish, without the consensus of the female fish, begin to act like a third party and excrete their own sperm to fertilize the egg.

The researchers found that the female ocellated wrasse has found a way to counter their rude deed. According to the study, during spawning, the female occelated wrasse releases an ovarian fluid along with the eggs.

"The sneaker males release more sperm than the nesting males, and you'd think that would give them a better chance to fertilize the eggs, but there is something in the ovarian fluid that removes that advantage," said first author Suzanne Alonzo, professor of ecology and evolutionary biology at UC Santa Cruz in a press release.

Through fertilization experiments, the researchers found out that the ovarian fluid ensures that the sperm of their "real partner" will get to the egg faster.

The study implies that direct selection in marine animals is possible and that it can affect the male traits being passed on from generations to generations.

"When we think about why marine species look and act the way they do, part of what we are seeing depends on this cryptic level of interactions between males and females, or really between eggs and sperm. It makes sense that you would see these kinds of effects in the reproductive tract, but that it's happening in the water is pretty amazing."

International Union for Conservation of Nature Red List describes ocellated wrasses as protogynous hermaphrodites that live in small groups, mainly over algal-covered rocky substrates, but also in seagrass beds throughout most of the Mediterranean Sea.