Scientists have expressed their admiration for the remarkable adaptability of remora fish, particularly species like Phtheirichthys lineatus, which exhibit generalist behaviors by attaching to a variety of hosts such as other fish, sharks, and turtles. In contrast, some remora species found in open waters display a more specialized nature, primarily latching onto larger marine animals like cetaceans, swordfish, and marlins. Notably, the species R. albescens distinguishes itself by adhering internally within the gill chambers and oral cavities of manta rays.
Credit:
Stephen Frink
In an effort to understand the unique adaptations of these fish, researchers conducted an in-depth examination of the anatomy of the remora’s adhesive disks. Their analysis indicated that the disks’ effectiveness is largely determined by the arrangement of lamellae. Generalist species possess a combination of both parallel and angled lamellae, while those that attach to fast-moving hosts primarily feature parallel organization. Conversely, R. albescens displays a diverse range of lamellae orientations without a dominant pattern.
With the aim of developing an innovative adhesive device suited for various underwater applications, including maritime exploration and underwater manufacturing, the research team initially set out to create a platform for drug delivery capable of securely adhering to the inner walls of the gastrointestinal tract. They selected the disks of R. albescens as their model since this species naturally adheres internally to its host, coining their invention the Mechanical Underwater Soft Adhesion System (MUSAS).
However, the design process involved more than simply mimicking nature. “We made several modifications,” said researcher Traverso.
Advancing Nature’s Design
A significant innovation was the adaptation for deployment within the gastrointestinal tract, posing the challenge of fitting the device into a capsule form. The team opted for the size 000 capsule, the largest ingestible form approved by the FDA, measuring 26 millimeters in length and 9.5 millimeters in diameter. MUSAS incorporates a supporting structure similar to that of the remora’s disks, yet it is constructed from stainless steel. The angled lamellae with spinules resemble those of R. albescens but are crafted from a shape memory nickel-titanium alloy. The function of the remora’s soft tissues, which generate suction by dividing the disk into compartments, is replicated by an elastomeric material.
