Shark with fins in the shape of a sickle that may only prefer warm waters

The Sicklefin smoothhound (Mustelus lunulatus) is a shark belonging to the family Triakidae. It is found on the continental shelves of the northeastern Pacific. There are several similarities between this shark and others within its genus, so at times it is hard to identify or has been identified mistakenly.


Family: Triakidae – Houndsharks

Genus: Mustelus 

Species: lunulatus


Phylum– Chordata

Class– Chondrichthyles


Common NameGround Sharks

Family– Triakidae

Common NameHoundsharks




Average Size and Length: They are born between 32-35 cm/1-1.1 feet. Mature males measure between 70-83 cm/2-2.7 feet and reach lengths greater than 110 cm/3.6 feet. Females reach 97 cm/3.1 feet. The maximum recorded is possibly 170 cm/5.5 feet.

Teeth and Jaw: The mouth is shorter than the Grey smoothhound and it also has shorter labial furrows. Their teeth are high cusped, and are arranged in a pavement like fashion, good for crushing.

Head: They have a more pointed snout and more widely separated eyes than the Grey smoothhound.

Demographic, Distribution, Habitat, Environment and Range: The Sicklefin smoothhound can be found in the northeast Pacific Ocean in southern California (possibly only in warm summers), to Panama (33° N and 7° N, 125°W – 78°W). They are found in warm temperate to tropical waters on the continental shelf, close inshore to well offshore. They are demersal and are possibly seasonally migratory.

Aesthetic Identification: The Sicklefin smoothhound is a large shark. It is unspotted grey or grey-brown dorsally, and lighter ventrally. The fins are strongly falcate.

Biology and Reproduction: Little is known about their reproduction. Some consider viviparous and others ovoviviparous.

Behavioral Traits, Sensing and Intelligence: Unknown.

Sicklefin Smoothhound Future and Conservation: They are currently of least concern. They are common to abundant within their range. They are important to longline fisheries for their meat.

Sicklefin Smoothhound Recorded Attacks on Humans: Not a threat to humans.