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Common smooth-hound: the shark with pavement teeth that cracks crustaceans

A shark without pointed teeth: according to German Wikipedia, the smooth-hound’s teeth are pavement-like and form no cusps — a tooth shape that, among sharks, exists only in its genus. With them it cracks whatever lives on the bottom, above all crustaceans. This article is about the common smooth-hound, *Mustelus mustelus* (also smoothhound) — German Grauer Glatthai (also Glatthai), Italian palombo (also palombo liscio and palombo comune), French émissole lisse, Spanish musola lisa (also musola), Portuguese cação-liso and caneja (GBIF), Dutch toonhaai, Danish glathaj (GBIF), Swedish sydlig hundhaj (also glatthaj), Norwegian glatthai, Finnish silokoirahai, Russian европейская кунья акула, Greek γκριζογαλέος (GBIF), Slovenian navadni morski pes, Albanian peshku pëllumb (GBIF) and Arabic كلب البحر الأملس الشائع (Wikidata). For Croatian and Japanese we found no species name of their own in Wikidata or GBIF, and we could not confirm the Turkish form listed by GBIF as being in common use. It is a predatory fish of the coastal seabed. Here you’ll find how to recognise it, what it eats, how it bears its young — and why it now ranks among the Endangered sharks.

A shark that cracks rather than tears

It was described by Carl Linnaeus in 1758, as *Squalus mustelus* (FishBase, English Wikipedia). Today it belongs to the family of houndsharks (Triakidae) in the order of ground sharks. According to German Wikipedia, its jaws are densely packed: 73 to 85 tooth rows in the upper jaw, 71 to 88 in the lower — flat teeth that sit side by side like paving. According to FishBase it feeds mainly on crustaceans, plus cephalopods and bony fishes. German Wikipedia also lists molluscs, echinoderms and worms.

How to recognise it

FishBase describes it as a large, plain-coloured smooth-hound: uniformly grey or grey-brown above, white below; it rarely has dark spots. According to German Wikipedia it is slender, the underside of the head is flat, and the eyes sit close to the top of the head. It has two dorsal fins and an anal fin; according to German Wikipedia, the first dorsal fin starts above the rear tips of the relatively small pectoral fins, the second is somewhat smaller, and the anal fin begins a little behind it. In males, the pelvic fins are modified into claspers (English Wikipedia).

  • Size: according to FishBase at most 200 cm total length, commonly 100 cm; English Wikipedia gives a usual length of 100 to 120 cm.
  • Age: according to FishBase up to 24 years.
  • Look-alike no. 1: the starry smooth-hound (*Mustelus asterias*), which according to English Wikipedia has white spots on its back — but they can fade.
  • Look-alike no. 2: the tope (*Galeorhinus galeus*); according to English Wikipedia, the smooth-hound has the larger second dorsal fin.

Where it lives

According to FishBase it lives in the Eastern Atlantic — from Great Britain southwards, including the Mediterranean, the Canary Islands and Morocco, and along the West African coast down to South Africa. It keeps to the continental shelves and the uppermost slopes, from the intertidal zone to at least 350 m depth, mostly between 5 and 50 m; in the eastern Ionian Sea it has been caught, according to FishBase, as deep as 624 m. It sometimes swims in open water, but prefers to stay close to the bottom. According to German Wikipedia it is an active swimmer that lives alone, but also in large groups, often sorted by body length.

Live-bearing, with a yolk-sac placenta

The smooth-hound lays no eggs. According to FishBase it is viviparous, and the embryos are nourished through a yolk-sac placenta. FishBase describes distinct pairing with embrace; according to FishBase a litter has 4 to 17 pups, around 39 cm long at birth. German Wikipedia gives a gestation of ten to twelve months and births in spring or early summer. According to FishBase it becomes sexually mature at 70 to 80 cm. Italian Wikipedia reports a curiosity: a single documented case of parthenogenesis — in a female at the aquarium of Cala Gonone in Sardinia.

Why every catch counts

Worldwide, the smooth-hound is listed on the IUCN Red List as Endangered, assessed on 4 August 2020 (FishBase). The reason is in FishBase’s numbers: its resilience is very low — a population needs more than 14 years to double — and its vulnerability to fishing stands at 84 out of 100, i.e. very high. At the same time, according to FishBase, it is heavily fished commercially and processed into food fish, oil and fishmeal; French Wikipedia names Spain above all. FishBase also lists it as a game fish: it is caught by shore anglers and from small boats. For you as an angler, that means: a smooth-hound on the hook is an animal from a stock that recovers very slowly. Minimum sizes, closed seasons, retention bans and rules for sharks differ by country and water — check them yourself before you fish, with the fisheries authority, your club, or your guide or skipper.

Five contradictions, left standing

  • How long does it get? FishBase and French Wikipedia: at most 200 cm. German Wikipedia: at most 1.65 m. Italian Wikipedia: over two metres.
  • How deep does it go? FishBase and French Wikipedia: 624 m. English, Italian and Spanish Wikipedia: 625 m. German Wikipedia: 650 m.
  • How many pups? FishBase and French Wikipedia: 4 to 17. German Wikipedia: 4 to 21. At birth, a pup measures around 39 cm according to FishBase, 35 cm according to English and Spanish Wikipedia, and 34 to 42 cm according to German Wikipedia.
  • How threatened is it? FishBase: Endangered (2020). French Wikipedia still says Vulnerable — an older assessment.
  • How far north? FishBase: up to Great Britain; German Wikipedia even names the southern North Sea. French Wikipedia considers this disputed: old records from northern Europe were probably unspotted starry smooth-hounds, and the IUCN map today ends in northern Portugal.

Four names that lead to the wrong shark

  • “Smooth dogfish”. GBIF also lists this English name for the common smooth-hound — but it usually refers to *Mustelus canis*, a close relative from the Western Atlantic. FishBase warns that our smooth-hound is often referred to as Mustelus canis, even though that species lives only in the Western Atlantic.
  • “Cazón”. GBIF also lists this Spanish name for the smooth-hound, but according to Spanish Wikipedia the cazón is the tope, *Galeorhinus galeus* — exactly the shark the smooth-hound gets confused with. It is similar in Slovenian: morski pes is used there for other sharks too — Slovenian Wikipedia calls the tope pepelasti morski pes; the smooth-hound is the navadni morski pes.
  • “Camgöz”. GBIF also lists this Turkish word for the smooth-hound, but Turkish Wikipedia uses it for many sharks: from the basking shark and the shortfin mako to the spiny dogfish, and “bayağı camgöz” there stands for *Mustelus canis*.
  • “ホシザメ” (hoshizame). According to Japanese Wikipedia, this is *Mustelus manazo* from the Northwest Pacific — a relative, not our smooth-hound. The genus is called ホシザメ属 in Japanese.

That leaves the question every article in this series starts with: when. Habitat, prey and habits are covered above, and they are fixed. What changes every day is everything else — light, air pressure, wind, water temperature, current — and whether a day on the coast is worth it is decided right there. That is what StrikeAhead calculates: it takes the conditions on your water and tells you when the trip is worth it. And because you don’t know an unfamiliar area, its spots and its rules from day one, StrikeAhead Pathfinder tells you who to go out with: curated guides and skippers, personally vetted before listing — licence and insurance — with verified catches instead of promo photos, no paid ranking, and no booking fee for you as an angler. The app tells you when, Pathfinder tells you who with.