Medical Research Council - London Institute of Medical Sciences

Now in our 12th year of bringing you beautiful imagery from biomedical science every day

29 April 2021

Head Over Hearts

Lizards shedding and re-growing their tails are probably the best-known examples of impressive regeneration in animals, but other species take autotomy, the voluntary loss of body parts, to an extraordinary extreme. Sea slugs Elysia cf. marginata (shown here) and E. atroviridis can separate their heads from the rest of their body, including their heart, and not only survive, but regenerate a complete body from the head section: feeding within hours, regrowing a heart within a week, and fully regenerating around three weeks after the break. Their diet may hold the key to surviving without major internal organs, as the sea slugs perform kleptoplasty, taking up chloroplasts from the algae they eat into their own tissues, to provide them with energy through photosynthesis. Why they undergo this traumatic process is still unclear, but it could be a means of shedding internal parasites – a radical response that reveals new champions of regeneration.

Written by Emmanuelle Briolat

Search The Archive

Submit An Image

What is BPoD?

BPoD stands for Biomedical Picture of the Day. Managed by the MRC London Institute of Medical Sciences the website aims to engage everyone, young and old, in the wonders of biomedicine. 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.