Flotation of aquatic worms and other hyponeuston

The California blackworm, Lumbriculus variegatus, lives underwater and latches its tail to the water surface for respiration and stability. Little is known about the upward force generated by this posture. In this combined experimental and theoretical study, we visualize the menisci shape for blackworms and blackworm mimics, composed of smooth and corrugated epoxy rods. We apply previous theoretical models for floating cylinders to predict the upward force and safety factor of blackworms as well as other organisms such as mosquito larvae, leeches and aquatic snails. Understanding the upward forces of organisms that latch onto the water surface may help to understand the evolution of interfacial attachment and inspire biomimetic robots.