Baby Nemos Can Go the Distance

As the hit animated film "Finding Nemo" taught us, clownfish typically spend their entire lives hiding in the protective tentacles of host anemones. But as it turns out, little Nemo's curiosity about the deep blue sea is not unheard of. In fact, baby clownfish sometimes travel hundreds of kilometers across the open ocean, promoting dispersal of offspring, according to new research.

The study, published in the journal PLOS ONE, found that six percent of the reef fish sampled like to go the distance, traveling over 400 kilometers (~250 miles) from one population to the other. Although, this journey only occurs at the larval stage of clownfish, contrary to what "Finding Nemo" may indicate.

"This is an epic journey for these tiny week-old fish. When they arrive at the reef, they are less than a centimeter long, and only a few days old, so to travel hundreds of kilometers they must be riding ocean currents to assist their migration," lead author Dr. Steve Simpson, from the University of Exeter, said in a press release.

The research team studied clownfish from throughout southern Oman, located off the coast of the Arabian Peninsula. Using DNA fingerprinting, they identified local, long-distant migrant, and hybrid individuals from Omani clownfish (Amphiprion omanensis) populations in the region. The fish were not harmed during this process, and were later returned back to their rightful colonies.

Based on these genetic signatures, which the researchers equate to human accents, they can determine whether or not each fish originated in the place from which it was caught.

The results show that young migrant fish mostly traveled from north to south, in line with the region's dominant ocean currents.

Also, second generation hybrids were found in both populations, indicating that after dispersal migrants had joined and reproduced with local populations.

"This study is the furthest anyone has tracked the dispersal of coral reef fish, and it demonstrates that distant populations in the marine environment can be well connected," Simpson said.

Not only does it help researchers better understand these typical homebodies, but their movements can also lead to better management of coral reef systems, as well as protection for vulnerable populations.