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.
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).
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.
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/
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!
Featured Image Source
Robertson, D. R. (Photographer). (n.d.). Mustelus canis NY Aquarium [Digital Image]. Retrieved from https://en.wikipedia.org/
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 Fishes, 54(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.