An accidentally discovered spurdog in Taiwan

The Taiwan spurdog (Squalus formosus) is a dogfish belonging to the Family Squalidae. It was accidentally found in Taiwan’s Tashi fish market by William Toby White and a colleague S.P. Iglésias in 2011 of the CSIRO in Hobart, Australia. Since then, they have also been recorded off the coast of Japan.


Family: Squalidae – Dogfish Sharks

Genus: Squalus 

Species: formosus


Phylum– Chordata

Class– Chondrichthyles



Common NameDogfish Sharks

Family– Squalidae

Common NameDogfish Sharks




Average Size and Length: The longest recorded female so far is 2.7 feet. The longest recorded male is 2.4 feet.

Head: The snout of the Taiwan spurdog is relatively short. The eyes of the Taiwan spurdog are slightly larger than the eyes of the Eastern Highfin spurdog at 4.8–5.3 (versus 4.4–4.8) percent of the total length. The preoral length is between 2.2–2.3 times that of the horizontal prenarial length. The head length is between 4.0–4.7 times the eye length. The interorbital width is between 1.4–1.6 times the horizontal preorbital length.

Denticles: The flank denticles are tricuspid.

Tail: The caudal fin has a broad white posterior margin and there is no dark caudal bar.

Demographic, Distribution, Habitat, Environment and Range: The Taiwan spurdog can be found in the Pacific Ocean in Taiwan and Japan.  has been recorded off the coast of Japan, in north-eastern Taiwan, and off Kyushu and Shikoku.

Aesthetic Identification: The Taiwan spurdog is considered medium sized. The first dorsal fin is tall and upright, and the upper posterior margin is almost straight. The Taiwan spurdog is morphologically closest to the Eastern Highfin spurdog but differs in the following characteristics: the first dorsal fin has a distinct, broad white anterior margin. The second dorsal fin height is 5.7–6.4 (versus 4.3–5.1) % of the total length. The first dorsal fin height is 9.0–10.5 (versus 7.7–8.9) percent of the total length. The anterior margin is 12.4–14.6 (versus 10.9–12.7) % of the total length. The pre-second dorsal fin length is between 3.7–4.4 times the length of the pectoral-fin anterior margin. The posterior margin of the second dorsal fin are deeply concave. The second dorsal-fin spine has a broad base. The dorsal surface of head is dark and sharply demarcated from the counter-shaded paler ventral surface.

Biology and Reproduction: They are thought to be ovoviviparous. There are 45–46 monospondylous centra, 94–95 precaudal centra, and 123–124 total centra.

Behavioral Traits, Sensing and Intelligence: Unknown.

Taiwan Sourdog Future and Conservation: Not enough data to evaluate.

Taiwan Spurdog Recorded Attacks on Humans: Not a threat to humans.