Full Breakdown
Remoras Slip into Manta Ray Cloacae: New “Cloacal Diving” Documented
5/12/2026, 11:19:37 AM
Core Observation: Remoras Enter Manta Ray Cloacae
Researchers recorded remoras—also called suckerfish—forcing themselves into the cloacal opening of manta rays. In some instances the fish entered fully, leaving only the tip of its tail visible; in others the ray’s size limited entry, resulting in half of the remora’s body protruding from the cloaca.
Background & Context: Known Remora Associations
Remoras are well known for attaching to larger marine hosts such as sea turtles, sharks, and whales to obtain transport and food scraps. Prior to this study, similar cloacal entries had been observed only in whale-shark cloacae. The current observations extend the behavior to manta rays, a host group not previously documented for this interaction.
Key Researchers & Organizations
- Catherine Macdonald – Director of the Shark Research and Conservation Program, University of Miami; senior author of the study.
- Marine Megafauna Foundation – Collected the observational data across multiple regions.
- Ecology and Evolution – Journal publishing the findings.
Timeline of Documented Events
- 2010-2025 – Seven separate instances of cloacal diving recorded.
- All three recognized manta-ray species – Each species contributed at least one observation.
- Three ocean basins – Pacific, Indian, and Atlantic regions represented in the dataset.
Data & Statistics
- 7 documented events across 3 manta-ray species.
- Observations span 3 distinct ocean basins.
- Behavioral variation includes full immersion (tail tip visible) and partial immersion (half the body exposed).
Official Statements & Responses
Catherine Macdonald emphasized that the behavior appears involuntary for the host, noting that “the manta ray does not seem to favor the intrusion.” The research team concluded that the repeated sightings across diverse locations suggest cloacal diving may be a more widespread, yet under-reported, facet of remora–manta interactions.
Criticism & Opposition
No dissenting viewpoints or critiques were presented in the source material regarding the study’s methodology or conclusions.
Conflicting Reports & Gaps
The limited sample size (seven events) prevents definitive statements about the frequency of cloacal diving among all remora–manta associations. Additional systematic observations are required to assess prevalence and potential physiological effects on manta rays.
Verbatim Quotes
> “It does not look like the manta ray likes it,” — Catherine Macdonald, Director, Shark Research and Conservation Program, University of Miami
Why It Matters: Implications for Symbiotic Interactions
Documenting cloacal diving expands the known repertoire of remora host-selection strategies and raises questions about the cost to manta rays, which may experience irritation or increased infection risk. The findings prompt a reevaluation of the mutualistic versus parasitic spectrum in remora-host relationships.
What’s Next: Future Research Directions
The authors recommend targeted monitoring of manta-ray populations using underwater video and tagging to capture additional cloacal diving events. Comparative studies with whale-shark interactions are also suggested to determine whether similar mechanisms drive the behavior across different host species.
