Western Spiny Brittle Star

What would you do if you could grow new arms and legs like a Western Spiny Brittle Star?

Latin Name: Ophiothrix spiculata

Western Spiny Brittle Star
Western Spiny Brittle Star at Cabrillo National Monument.

You might have noticed that this small Western Spiny Brittle Star has lost part of a leg. In time this arm should regenerate or regrow. We found this guy in the tidepools at Cabrillo National Monument.

Sea stars have a remarkable ability to regenerate, or regrow, their arms and tube feet. Most kinds of sea stars need at least part of their central disk to be intact in order to regenerate arms, but a few tropical species can grow an entire body from just a severed limb. Regeneration of arms is not a fast process; it can take up to a year for larger sea stars.

Western Spiny Brittle Star diagram
Western Spiny Brittle Star diagram

Western Spiny Brittle Star Stats

Description: Spiny.  Orange, yellow, tan, brown, green, variously patterned. Long, thorny spines on margins of arms and disk.

Size: Disk diameter ¾ in (19 mm), arm length 6 in (15 cm)

Habitat: water depth 0.35 m Under rocks, in crevices and mats of algae or invertebrates; from low-tide line to water 660 ft (2012 m) deep

Range: Kelp holdfasts and clumps of bryozoans and worm tubes are often writhing masses of Western Spiny Brittle Star arms. 

Diet: Brittle stars are mainly detrivores (detritus-eaters); they eat decaying matter and plankton. Some brittle stars can also kill small animals. They push their stomach out through their mouth (which is located on the underside of the disk of the brittle stars) and digest the prey (there is no anus).

Fascinating Fact: Western Spiny Brittle Star’s anchor themselves with spines of one or more arms. They then extend their other arms into the water for filter feeding.

Fascinating Fact: If a brittle star’s arm is cut off, it will regenerate (regrow).

Scientific Classification

Kingdom: Animalia
Phylum: Echinodermata
Class: Ophiuroidea
Order: Amphilepidida
Family:  Ophiotrichidae
Genus: Ophiothrix
Species: Ophiothrix (Ophiothrix) spiculata

Follow Us to Find Out More Cool Creature Stuff!

The San Diego Creature Project is an animated children’s program created by kids, for kids. Follow three brothers, their cousin, and their dog Ryan as they solve creature mysteries with science and learn about life in Southern California.


Red Tuna Crabs

Tuna Crabs, SD Creature Project

Remember to Red Crabs or Red Tuna Crabs?

Tuna Crabs, San Diego Creature Project
Tuna Crabs

Every so often, maybe every couple of years, the beaches are covered with these small bright red crabs. They’re called Red Tuna Crabs, although they’re not tuna or crabs. These crustaceans look like crayfish, but they are a type of squat lobster—not a true crab. 

Ryan, our Vizsla dog, had a lot of fun when the crabs arrived at the Ocean Beach, Dog Beach here in San Diego. Ryan also happens to be red. That was when he started his new hobby… fishing! He didn’t eat anything he caught. He’d track them down, pick them up gently in his mouth (Vizslas have a soft mouth), and then put them back.

The OB Dog Beach is a wonderful place where dogs are allowed to run and play off leash. If you have a well behaved dog or a puppy that needs socialization, this is a great place to explore and learn.

Tuna crabs primarily inhabit, or live in the west coast of Baja California, Gulf of California, and the California Current. These creatures are unique in that it can live their whole life cycle (from larvae to adult) in the water column (surface to seafloor).

The omnivorous crustaceans eat phytoplankton, or really tiny plants, in open water, and larger adults crawl along the sea floor. Pelagic red crabs are not safe for humans to eat because they may ingest toxin-producing plankton, but lots of larger ocean creatures love to snack on them. 

Learn more about Red Tuna Crabs at:


The San Diego Creature Project is a children’s television program created by kids, for kids. Follow three brothers, their cousin, and their dog Ryan as they solve creature mysteries with science and learn about life in San Diego and Southern California.

#crustacean #oceanlife #beach

San Diego Creature Project