Suckerfish Are Disappearing into Manta Rays’ Rear Ends. Researchers Say They’re ‘Just That Weird’

Marine researchers have recently turned their attention to an unusual behaviour exhibited by suckerfish, known scientifically as remoras. These small fish, typically seen latch onto larger marine animals for shelter, have been observed engaging in a curious practice: diving into the rear ends of manta rays. This behaviour has been documented seven times over the last 15 years, prompting questions about the reasons behind it and its potential consequences.

Emily Yeager, a marine researcher at Miami University and senior author of a study published in Ecology and Evolution, explained, “We think this is an under-reported phenomenon because, oftentimes, you just see the very tip of the tail poking out from the backside of the manta ray.” Yeager believes that the actual occurrences of this behaviour may be far more common than the recorded instances, as many may go unnoticed by divers and researchers alike.

Through direct observations, scientists have surmised that the suckerfish may be reacting to perceived threats by seeking refuge within the manta ray. One notable incident involved a remora disappearing into a manta ray’s cloaca after a diver inadvertently startled it, showing how quickly these fish can make themselves at home in such a peculiar space. Despite the brief discomfort observed in the manta ray, it continued swimming with the remora firmly in tow.

The recent study brings forth concerns regarding the potential impact of this behaviour on the manta rays. While remoras traditionally engage in symbiotic relationships with their hosts—providing cleaning services in exchange for protection and transport—this intrusive behaviour might lead to skin damage. Yeager noted that the remoras’ suction cups could inflict harm on the delicate skin surrounding the mantas’ cloaca, which is particularly sensitive compared to other areas of their bodies.

Brooke Flammang, a professor of biological sciences at the New Jersey Institute of Technology, offered an alternative perspective on the motive behind the remoras’ actions. She speculated that the behaviour may be driven by “coprophagy,” a Latin term for the consumption of faeces, suggesting that the suckers are possibly foraging for food rather than merely seeking safety. Flammang further pointed out that remoras can be territorial, particularly when sharing space on the same host, which may complicate their interactions with manta rays.

Yeager echoed concerns regarding the implications of this behaviour for manta rays. “It could cause really severe damage and influence reproduction and also excretion of waste over time,” she remarked, emphasising the need for further investigation into how these interactions affect both the fish and their larger hosts. The complexities of their relationships challenge the simplistic frameworks often used to describe symbiosis in nature.

The findings highlight a broader understanding of interspecies relationships, indicating that not all interactions can be neatly categorised. “Oftentimes when we think of nature, we like to put these relationships into pretty discrete boxes so we can define them easier,” Yeager noted. “But what this has taught me is that these relationships probably exist on a spectrum, just like any relationship in your life.”

As researchers continue to study these fascinating behaviours, the interactions between suckerfish and manta rays serve as a reminder of the complexities of marine life. The marine ecosystem is filled with intricate relationships that challenge our understanding of animal behaviours and survival strategies.

In conclusion, the observed behaviour of remoras diving into manta rays presents both intriguing insights and potential risks. Marine research is invaluable in uncovering these lesser-known behaviours and understanding their ecological impacts, paving the way for more comprehensive studies in the future.