Researchers study adhesion system of remora fish to create bio-inspired adhesive

When a shark is spotted in the ocean, humans and marine animals alike usually flee. But not the remora – this fish will instead swim right up to a shark and attach itself to the predator using a suction disk located on the top of its head. While we know why remoras attach to larger marine animals – for transportation, protection and food – the question of how they attach and detach from hosts without appearing to harm them remains unanswered.

A new study led by researchers at the Georgia Tech Research Institute (GTRI) provides details of the structure and tissue properties of the remora's unique adhesion system. The researchers plan to use this information to create an engineered reversible adhesive inspired by the remora that could be used to create pain- and residue-free bandages, attach sensors to objects in aquatic or military reconnaissance environments, replace surgical clamps and help robots climb.

''While other creatures with unique adhesive properties – such as geckos, tree frogs and insects – have been the inspiration for laboratory-fabricated adhesives, the remora has been overlooked until now,'' said GTRI senior research engineer Jason Nadler. ''The remora's attachment mechanism is quite different from other suction cup-based systems, fasteners or adhesives that can only attach to smooth surfaces or cannot be detached without damaging the host.''

The study results were presented at the Materials Research Society's 2012 Fall Meeting and will be published in the meeting's proceedings. The research was supported by the Georgia Research Alliance and GTRI.

The remora's suction plate is a greatly evolved dorsal fin on top of the fish's body. The fin is flattened into a disk-like pad and surrounded by a thick, fleshy lip of connective tissue that creates the seal between the remora and its host. The lip encloses rows of plate-like structures called lamellae, from which perpendicular rows of tooth-like structures called spinules emerge. The intricate skeletal structure enables efficient attachment to surfaces including sharks, sea turtles, whales and even boats.

To better understand how remoras attach to a host, Nadler and GTRI research scientist Allison Mercer teamed up with researchers from the Georgia Tech School of Biology and Woodruff School of Mechanical Engineering to investigate and quantitatively analyze the structure and form of the remora adhesion system, including its hierarchical nature.