S2 Ep 24. The world’s most efficient swimmer is the moon jellyfish! It’s the inspiration for a soft underwater robot that is safe enough to use in fragile environments like coral reefs and aquatic archaeological sites. By contracting a ring of muscle, the jellyfish can push water out of their bell-shaped bodies, thrusting them forwards without using much energy at all. Get in touch: www.bbcworldservice.com/30animals #30Animals