In a recent development, it has been discovered that remoras, commonly known as suckerfish, might not always be the most considerate companions during their aquatic travels. These small fish hitch rides across oceans by attaching themselves to larger marine animals such as sharks, whales, and manta rays, feeding on parasites in exchange for the free ride. However, new research indicates that having a remora along for the journey could pose a potential downside for manta rays.
Marine researcher Emily Yeager, a PhD candidate at the University of Miami, revealed in an interview with “As It Happens” host Nil Kӧksal that these fish exhibit a behavior termed “cloacal diving.” This behavior involves the fish plunging into the host’s cloaca, a single orifice for reproduction and excretion.
While cloacal diving has been observed between remoras and whale sharks in the past, interactions between remoras and manta rays were documented for the first time in a recent study led by Yeager. The study highlighted seven instances of this behavior occurring over a 15-year period in various oceanic regions, with researchers suspecting that it happens more frequently than reported.
Yeager suggested that the remoras’ actions might stem from a fear response, as observed in a video where a remora hastily dives into a manta ray’s cloaca after being startled by a diver. This behavior could potentially harm the manta ray, affecting its reproductive and waste excretion processes due to the sensitive nature of the cloaca opening.
Brooke Flammang, a biological sciences professor at the New Jersey Institute of Technology who has studied remoras, proposed that the behavior could be linked to the fish seeking a food source, a behavior known as “coprophagy,” or consuming feces. She mentioned that remoras are not typically skittish around divers and can even latch onto humans like they would any other host.
As researchers delve deeper into the implications of cloacal diving on manta rays, Yeager emphasized that the incident challenges the traditional categorization of the relationship between remoras and their hosts as either symbiotic or commensal. She suggested that these interactions likely exist on a spectrum, akin to relationships in everyday life, rather than fitting into rigid categories.
This intriguing discovery sheds light on the complex dynamics between marine species and underscores the need for further research to understand the implications of such interactions on the delicate ecosystems of the ocean.