Now in our 13th year of bringing you beautiful imagery from biomedical science every day

Search the archive of over 4000 images

Cnidarian weapon – inspiration for microdevices with biomedical application

05 July 2022

Sting Operation

Jellyfish, sea anemones and other cnidaria wield explosive weapons – harpoon-like 'stings' that burst from tiny capsules or nematocysts on the surface of their skin, impaling prey or deterring predators. Here scientists reconstruct a sea anemone harpoon, the basitrichous isorhiza, from scans taken with scanning electron microscopy. The shaft of the sting (blue) is connected to a coiled tubule (pink) which springs outwards, skewering a meal and turning the capsule inside out by a process called eversion. With the process zipping by in 700 nanoseconds, the team looked closely at the biomechanics involved, finding the strands of the shaft uncoil outside the capsule, propelling an inner tubule covered in barbs towards the target. The elegant design of this deadly micromachine may now be repurposed, putting the same mechanics into needles to treat humans – a helping hand from cnidarians, our distant genetic ancestors.

Written by John Ankers

Search The Archive

Submit An Image

Follow on Tumblr

Follow on Instagram

What is BPoD?

BPoD stands for Biomedical Picture of the Day. Managed by the MRC Laboratory of Medical Sciences until Jul 2023, it is now run independently by a dedicated team of scientists and writers. The website aims to engage everyone, young and old, in the wonders of biology, and its influence on medicine. The ever-growing archive of more than 4000 research images documents over a decade of progress. Explore the collection and see what you discover. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.

Read More

BPoD is also available in Catalan at with translations by the University of Valencia.