Featured Species: Dusky Smoothhound (Mustelus canis)

This week’s Featured Species is one of the 46 species of hound sharks that belong to the family Triakidae. The dusky smoothhound shark, also known as the smooth dogfish, (Mustelus canis) is a relatively small shark species, reaching lengths up to 5 feet (1.5 m). It has a long, slender body, with two dorsal fins of roughly equal size, and large eyes. I must admit the first time I ever saw these guys in person, I made the girliest “squeeee” sound over their cuteness. I just couldn’t help myself.

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Flannery, A. (Photographer). (2018 June 12) Dusky Smoothhound shark at Indianapolis Zoo [Digital Image]. Original Content.

The dusky smoothhound lives in the warm shallow waters of the Western Atlantic and Caribbean Sea. These hound sharks are  nocturnal by nature, coming out of their day time resting places at night to hunt (Skomal, 2016). And they are expert crustacean hunters! Their jaws are full of specialized, pavement-like teeth that crush down on the shells of rock, lady, and blue crabs, mollusks, horseshoe crabs, and teleosts (Gelsleichter, et al., 1999). As juveniles, they are known to forage for prey that isn’t as difficult to crack, like squid, gastropods, annelid worms, some bivalve species, and even small bony fishes (Bigelow & Schroeder, 1948).

Mustelus_canis_jaws
Robertson, D.R. (Photographer). (n.d.). Mustelus canis jaws [Digital Image]. Retrieved from https://en.wikipedia.org/

I mentioned that the dusky smoothhound shark is nocturnal. So how does a shark rest during the day? I’m sure you’ve probably heard the myth at one point or another that all sharks need to keep moving in order to breathe. That is true for a small percentage of sharks, those known as obligate ram ventilators. Whale sharks and hammerhead sharks are obligate ram ventilators. But some sharks are able to pump water over their gills by opening and closing their mouths. This is known as buccal breathing. Nurse sharks and lemon sharks do this when resting on the sea floor. But the dusky smoothhound doesn’t belong to any of these categories. Instead they use a special funnel like cavity located on the tops of their heads just behind the eye known as a spiracle. These spiracles provide canals for water to pass over their gills without forcefully pumping water through their mouths (Skomal, 2016). This way these little guys, like the one sleeping behind me below, can catch all the zz’s they want throughout the day snuggled peacefully on the sea floor.

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Flannery, A. (Photographer). (2018 June 12). Dusky Smoothhound Shark Selfie [Digital Image]. Original Content.

If you’d like a demonstration on the breathing methods of sharks, check out this quick video by Shark Academy!

 

BlueWorldTV (Videographer). (2014 July 13). How Do Sharks Breathe? | Shark Academy [Video Clip]. Retrieved from https://www.youtube.com/

Shark Stats

Authority: Mitchill, 1815

Family: Triakidae, 46 species

Length: Approximately 5 feet (1.5 m) maximum

Weight: 15 lbs (6.8 kg)

Habitat: Continental shelves, shallow coastal waters, sounds, bays, harbors, estuaries

Depth: Shallow surface waters to a maximum of 650 feet (200 m)

Reproduction: Placental Viviparous

Gestation: 11 – 12 months

Litter Range: 4 – 20 pups

Home Range: Tempera waters in Western Atlantic

Diet: Crustaceans, small fishes

IUCN Status: Near threatened; taken by commercial and recreational fisheries, usually as bycatch

(Conrath, 2009; Skomal, 2016)

Thanks so much for checking out the adorable dusky smoothhound! Remember to swim over to last week’s featured species: the Bull Shark. If there is a species of shark you’d love to know more about, leave me a comment or send me a message! I would love to do a feature on your favorite species.

The new Ocean For Sharks Shop is open! There’s handmade ocean inspired plush animals, canvas paintings, and of course my children’s book, Winifred the Wondrous Whale Shark, available in print and PDF. Be sure to stop by. Remember proceeds benefit shark research and conservation with a donation to Project AWARE!

As always, remember you can make a difference for marine ecosystems by contacting your Congress man or woman and telling them that you care about the quality of our waters! Sharks, rays, and other marine organisms cannot speak or be represented in Congress. They need your voice. Get involved and stand up for sharks. Until next time finatics!

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Featured Image Source

Robertson, D. R. (Photographer). (n.d.). Mustelus canis NY Aquarium [Digital Image]. Retrieved from https://en.wikipedia.org/

Literature Cited

Bigelow, H. B., & Schroeder, W. C. (1948). Fishes of the Western North Atlantic. Part 1 (Lancelets, Cyclostomes, Sharks).

Conrath, C. (2009). Mustelus canis The IUCN Red List of Threatened Species 2009. Retrieved from http://www.iucnredlist.org/details/39359/0

Gelsleichter, J., Musick, J. A., & Nichols, S. (1999). Food habits of the smooth dogfish, Mustelus canis, dusky shark, Carcharhinus obscurus, Atlantic sharpnose shark, Rhizoprionodon terraenovae, and the sand tiger, Carcharias taurus, from the northwest Atlantic Ocean. Environmental Biology of Fishes54(2), 205-217.

Skomal, G. (2016). The Shark Handbook: The Essential Guide for Understanding the Sharks of the World. (2nd ed.). Kennebunkport, ME: Cider Mill Press.

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