Sea squirts are regeneration experts Liza Gross/CC BY 2.5

Marine animals called sea squirts can regenerate their entire bodies from nothing but a tiny fragment of a blood vessel. Their secret is a special population of stem cells floating in their blood.

The finding could help us understand how such regenerative abilities evolved. In the long run, it could also help doctors regenerate damaged or lost tissues or even limbs in our own bodies.

Sea squirts are oval or cylindrical animals a few centimetres across. They belong to a larger group of animals called the chordates, most of which are …