Quantitative Detachment Mechanics of Hydra from Substrates

  • Neha Khetan Div. of Biology, IISER Pune
  • Shagun Maheshwari Div. of Biology, IISER Pune
  • Chaitanya Anil Athale IISER Pune
Keywords: Hydra, shear-stress, biomechanics, somersaulting, flow-chamber, detachment


Hydra is a fresh water hydrozoan living as a solitary polyp with a sedentary feeder lifestyle attached to a substrate. In times of food short- age they are reported to detach from their substrate and move either by drifting or ‘somersaulting’. However, the quantification of the mechanical strength of the adhesion of Hydra has not been reported before. Here, we measure the force required to detach Hydra vulgaris and Hydra magnipapillata from a surface and the role of the nutritional state and substrate rigidity. For detachment force measurement, we have developed a cali- brated flow system based on a syringe pump. We find the detachment shear stresses are similar whether the animal is well-fed or starved in the two species tested- H. vulgaris and H. magnipapillata. On the other hand adhering to a hard substrate like a glass cover slip requires more force to detach H. vulgaris as compared to a soft substrate like polyacrylamide gel. Detachment stresses also differ across the two species in the same state. Taken together it suggests mechanics of the substrate and ambient flows in the water body could affect passive locomotion of Hydra, while suggesting the magnitude of muscle-based forces required to actively detach it from the substrate.

Author Biographies

Neha Khetan, Div. of Biology, IISER Pune

PhD student in the lab of Dr. C. A. Athale in the Biology division of IISER Pune. Neha has a B.E. degree from Bangalore University.

Shagun Maheshwari, Div. of Biology, IISER Pune

Shagun Maheshwari has a Masters in Engineering from Duke University USA

Research Papers