Western Spiny Seahorse, Hippocampus angustus Günther 1870

Shark Bay, north to the Dampier Archipelago, Western Australia. Inhabits sheltered bays with soft corals and soft sediment substrates adjacent to coral reefs, including seagrass beds.

Dorsal fin 17-19 (usually 18); Pectoral fin 15-19 (usually 16-17); trunk rings 11; tail rings 32-35 (usually 33-34); subdorsal rings 2 + 1.

Body slender; head angled downward from longitudinal axis of trunk; snout long, length 2.2 (2.0-2.5) in head length.
Spines well-developed, tips blunt or sharp, usually low in neck region; cheek spines sharp, double; double spine below eye; eye spine sharp, prominent; subdorsal spines 3/0,1,0.
Coronet moderately high with 5 well-developed sharp divergent spines.
Dorsal fin short-based.
A series of small pores, more or less distinct, extending to 20^th tail ring, pores difficult to detect posteriorly.

Height to 160 mm.

Overall grey to brownish, orange or reddish, often with a combination of white, yellow, orange or brown fine scribbly or net-like markings on the head and body; 5-6 distinctive dark irregular stripes across the snout; and a narrow dusky submarginal band on the dorsal fin. In preservative - pale brown with thin dusky bars on snout and scribble markings on head and body.

Like other seahorses, this species presumably feeds by sucking small crustaceans and other planktonic organisms into its mouth.

The sexes are separate and it is the male seahorse that broods the developing young. The female deposits her eggs into an elaborate enclosed pouch on the abdomen of the male. He fertilizes the eggs inside the pouch and provides physical protection for the developing embryos. He also osmoregulates and aerates the embryos and may even provide some nourishment until the tiny young are born. The larvae are miniature versions of the adults and are independent once they leave the pouch.

Although taken as bycatch in commercial trawls, this species is not traded commercially.

CITES Listed: Listed under Appendix II of the Convention on the International Trade in Endangered Species of Wild Flora and Fauna (CITES).
EPBC Act 1999: Marine Listed under the Federal Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act 1999)

Seahorses are very poor swimmers and rely on camouflage to blend in with their surroundings and avoid predators.

The Western Spiny Seahorse has been confused with Hippocampus histrix, H. spinosissimus and H. multispinus.

The specific name is from the Latin angustus (= narrow), in reference to the narrow body of this species - "but little dilated in males, … females still narrower”.

Hippocampus angustus Günther 1870, Cat. Fish. Brit. Mus. 8: 200, Freycinet's Harbour (Shark Bay, Western Australia).

Bray, D.J. & Thompson, V.J. 2024

Atlas of Living Australia