How to Identify Smooth-hound

To identify Smooth-hound (Mustelus mustelus), look at these key features.

Physical Characteristics

Body shape

elongated

Coloration

Dorsal surface typically grey to grey-brown, sometimes with a faint bronze sheen. Ventral surface is white or off-white. Juveniles may exhibit faint dark spots, which fade with age.

Scale type

placoid

Mouth position

inferior

Distinctive features

Slender, fusiform body., Blunt, rounded snout., Absence of spines on dorsal fins., Pavement-like teeth, adapted for crushing., Two dorsal fins of similar size., Anal fin present.

Dorsal fin

Two dorsal fins, roughly equal in size. The first dorsal fin originates over the pectoral fin bases, and the second dorsal fin originates over the pelvic fin bases. Both lack spines.

Tail fin

Heterocercal caudal fin, with the upper lobe longer than the lower lobe, but not deeply notched.

Pectoral fin

Broad and triangular.

Distinctive fins

All fins are relatively small in proportion to the body. The anal fin is present and smaller than the second dorsal fin.

Identification Tips

1. 1

   Teeth

   Unlike many other sharks, Smooth-hounds possess small, flattened, pavement-like teeth, without cusps, designed for crushing rather than tearing. This is a key distinguishing feature.

2. 2

   Dorsal Fins

   The absence of spines anterior to the dorsal fins is a definitive characteristic, differentiating it from spiny dogfish (Squalus acanthias).

3. 3

   Snout

   Its snout is relatively short and blunt, not pointed or elongated.

4. 4

   Coloration

   Generally uniform grey to grey-brown dorsally, lacking prominent spots or markings in adults, which helps distinguish it from some other Mustelus species like the Starry Smooth-hound (Mustelus asterias) which has distinct white spots.

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