### Blue Sea Star
Linckia laevigata
It can snap off its own arm to escape a predator, and that severed limb crawls away to clone itself.
The Story
Imagine you're grabbed by a hungry monster. To escape, you pop off your own arm and run away. But the true superpower doesn't belong to the survivor—it belongs to the severed limb. Meet the Blue Sea Star (Linckia laevigata), a bright blue ocean crawler spanning 30 to 40 centimeters across.
When a predator attacks, this animal performs a miraculous escape trick that leaves a piece of itself behind. Because a sea star's vital organs stretch all the way down into its limbs, that severed arm doesn't die. It becomes a crawling, eating survivor. Looking exactly like a shooting star—earning it the nickname "comet"—the lonely limb spends the next 10 months slowly building an entirely new body from scratch, complete with four brand-new arms and a fresh central mouth.
How It Works
- Autotomy: To escape a trap, the sea star voluntarily softens its own connective tissues, allowing the arm to cleanly snap right off. - The Blastema: Once separated, the wound on the "comet" arm heals over. The cells at the stump revert to a flexible state to form a blastema—a biological construction site that maps out and regrows the missing central disc and remaining arms. - Hydrostatic Tube Feet: The severed arm doesn't just sit there for 10 months. It actively crawls around, pumping seawater through a water-vascular system to power hundreds of tiny tube feet at a top speed of 8.1 centimeters per minute.
