Marine scientist Emily Yeager shared in an exclusive interview that suckerfish, also known as remoras, can be inconsiderate travel companions. These small fish hitch rides on larger marine creatures like sharks, whales, and manta rays, feeding on parasites in return. However, recent research indicates that manta rays may face discomfort due to the presence of remoras.
Yeager, a marine researcher at the University of Miami, discussed a peculiar behavior termed “cloacal diving,” where remoras dive into the cloaca of their hosts, a combined reproductive and excretory opening. While this behavior was previously observed between remoras and whale sharks, the interaction with manta rays is a new discovery.
The study, led by Yeager and published in the journal Ecology and Evolution, documented seven instances of cloacal diving over 15 years. Yeager highlighted that this phenomenon may be more widespread than reported, with remoras often concealed within the manta ray’s cloaca.
Brooke Flammang, a biological sciences professor at the New Jersey Institute of Technology, suggested that the behavior could be related to coprophagy, or eating waste. Flammang explained that remoras might dive into manta rays’ cloacas in search of food, potentially competing with other remoras for resources.
While the impact on manta rays remains unclear, Yeager expressed concerns about potential harm caused by remoras’ suction cups. If cloacal diving leads to skin damage in sensitive areas, it could affect manta rays’ reproduction and waste excretion. Yeager emphasized that such interactions challenge traditional classifications of symbiotic or commensal relationships between species, suggesting that nature’s dynamics are more complex and varied.