Fragile Star
Linckia columbiae

Physical Description

• Five-armed sea star, with thin arms and a small radial disc.
• Red and gray mottled coloration.
• The normal number of limbs is five, but can have anywhere from one to nine.
• Arms are often not symmetrical, due to ability to regrow new arms and discs.
• Maximum size is 4 inches in diameter.

Range

• Southern California to Peru.
• Ecuador (Galapagos Islands).
• May also be present in Hawaii.

Habitat

• Lives in the rocky intertidal.
• Found at depths of 0 to 500 feet.

Reproduction

• Embryos hatch into biradially symmetric (foldable on one line of symmetry) planktonic larvae that later transform into pentaradially symmetric (foldable on five lines of symmetry) juveniles with stubby arms.

Diet

• Sea stars eat mollusks and detritus.

Predators

• Fragile sea stars are considered rather inedible, although sea stars can be eaten by seabirds, fish, crabs, otters, and even other sea stars. 

Interesting Facts

• The fragile star is known to undergo autotomy, or self-amputation, where one arm detaches itself from the disc. That arm then regrows a new disc and new arms, a process that can take six months or more to complete. This is often why fragile stars look asymmetrical – they are in the process of regrowing their bodies! 

Sources: darwinfoundation.org; Reef Life Survey; Between Pacific Tides: Fifth Edition; National Aquarium; Benthic Invertebrates of Four Southern California Marine Habitats; sealifebase.ca

Photo: Matthew Meier