Spiny Sand Star
Astropecten armatus

Physical Description

  • A small, flattened starfish, which grows to a diameter of about 7 inches
  • The center disc is quite small and the five arms are slender and pointed, slightly turned up at the tips
  • Colors on back can range from white to gray to dull pink to yellow-brown to lavender, while colors on belly are light yellow or ivory
  • Spiky tips on the end of the tube feet

Range

  • The eastern Pacific Ocean off of Mexico
  • San Pedro, California to Ecuador

Habitat

  • In sandy or soft gravel seabeds, often hidden in the sediment
  • Sandy patches near reefs
  • Depth 0 to 525 feet

Diet

  • Primarily feeds on the olive snail (Olivella biplicata)
  • Also eat sand dollars, sea pens, sea pansies (Renilla reniformis), sea urchins, and scavenge on dead fish 

Predators

  • Sea gulls and crabs often eat intertidal sea stars, though predators of spiny sand stars are unknown

Interesting Facts

  • This species is an agile sea star and can move quickly. It can “glide” across the surface of the sand with its mobile tube feet
  • They do not have suckers on their tube feet like other sea stars, but instead have small points on the ends that can be used to bury themselves in the sand
  • If turned upside down it can right itself with a flip and if several are stacked on top of each other, they will quickly disperse

Sources: Monterey Bay Aquarium; Intertidal Invertebrates of California (p. 119); Mexican-Fish.com; MarineLifePhotography; Reeflex; Sea Stars of the Pacific Northwest

Photo: Derek Tarr

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