Short-spined Crown-of-Thorns Starfish

Invertebrates > Starfish & Echinoderms

AT A GLANCE
Common Name: Short-spined Crown-of-Thorns Starfish
Scientific Name: Acanthaster brevispinus
Category: Invertebrates
Subcategory: Starfish & Echinoderms
Size: Diameter: 8–16 in (20–40 cm); 11 to 16 radial arms
Weight: 1.1–2.2 lb (500–1,000 g)
Lifespan: Estimated 8–15 years in deep benthic waters
Diet: Carnivore / Benthic forager (mollusks, soft corals, bivalves, and organic encrusting epifauna)
Habitat: Sublittoral soft sand substrates and continental shelf slopes (depth 20–100 m)
Range: Indo-West Pacific marine basin
Conservation Status: Data Deficient (IUCN Red List / Locally Monitored)

Overview

The Short-spined Crown-of-Thorns Starfish (Acanthaster brevispinus) is an intriguing, little-known echinoderm of the Indo-West Pacific. Unlike its infamous reef-destroying shallow-water cousin (Acanthaster planci), this multi-armed starfish inhabits deeper, soft-bottomed sediment habitats along continental shelves, sporting distinctly shortened, blunt spines and a calm, non-outbreak benthic lifestyle.

Biology and Physical Characteristics

Acanthaster brevispinus possesses 11 to 16 flexible radiating arms encircling a broad central disc. Its upper surface is coated in a dense carpet of short, conical calcarean spines surrounded by venomous glandular tissue containing plancitoxin saponins. Colored in subtle hues of mauve, reddish-brown, or violet, the species features hundreds of hydraulic tube feet on its oral surface that enable steady transit across soft seabed mud and sand.

Behavior and Ecology

While the common crown-of-thorns feeds voraciously on reef-building scleractinian corals, Acanthaster brevispinus is adapted for life on soft sediment plains. It feeds opportunistically on buried bivalves, polychaetes, detrital encrusting mats, and solitary corals, everting its stomach through its mouth to digest prey externally. Spawning occurs broadcast into seasonal offshore currents, where planktotrophic larvae develop before settling onto deeper soft substrates.

Conservation and Human Impact

Due to its deeper, non-destructive foraging habits, Acanthaster brevispinus does not trigger the devastating reef-killing population booms associated with other crown-of-thorns species. However, bottom-trawl fisheries and marine dredging alter its seabed substrate. Further taxonomic and ecological studies are underway to map its full distribution and evolutionary lineage.

Interesting Factoid

Unlike its destructive shallow-water cousin that devours coral reefs, the short-spined crown-of-thorns lives peacefully on deep muddy sea plains, scavenging buried clams and worms with shortened defensive spines.

Last updated: October 2026