What's happened
A new study in Ecology and Evolution documents seven instances of remoras entering mantas’ cloacas across three basins over 15 years. The behavior—dubbed cloacal diving—likely ranges beyond observed cases and could affect manta physiology and reproduction, prompting questions about symbiosis versus parasitism.
What's behind the headline?
What this means for readers
- Remoras may be more invasive than once thought, challenging the idea of a purely mutualistic relationship.
- The behavior could influence cloacal function and long-term health of manta rays, affecting reproduction and waste excretion.
- This raises questions about how widely this behavior occurs across oceans and manta populations.
Why it matters
- If cloacal diving is frequent, it could alter how scientists understand host-symbiont dynamics in marine ecosystems.
- The finding may influence future marine wildlife management and conservation priorities.
Next steps
- More longitudinal observations are needed to determine frequency and drivers.
- Researchers will likely explore physiological impacts on hosts and fitness consequences for remoras.
How we got here
Researchers have been recording unusual remora behavior for years; this study extends observations to manta rays, suggesting cloacal diving is more common than previously known and could have implications for manta biology and host fitness.
Our analysis
New York Times reports on the study led by Catherine Macdonald of the University of Miami, published in Ecology and Evolution, noting seven instances of cloacal diving across three basins between 2010 and 2025. The NYT describes remoras as sometimes following manta rays and possibly engaging in coprophagy or territorial foraging behavior. The Guardian and NY Post cover related, though separate, marine behavior stories, while The Independent discusses regulatory implications for marine protections in a different context.
Go deeper
- What caused remoras to engage in cloacal diving in these observed cases?
- How might this behavior affect manta reproduction and health?
- Could this change influence conservation strategies for manta populations?
More on these topics
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Remora - Fish
The remora, sometimes called suckerfish, is any of a family of ray-finned fish in the order Carangiformes. Depending on species, they grow to 30–110 cm long.
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University of Miami - Private university in Coral Gables, Florida, United States
The University of Miami (UM, UMiami, Miami, U of M, and The U) is a private research university in Coral Gables, Florida, United States. As of 2024, the university enrolled 19,852 students in two colleges and ten schools across over 350 academic majors...