Saturday, May 26, 2012
Dogfish are small sharks that grow up to a few feet in length. Like some other shark species, they are counter-shaded. Their coloration is dark on the top half of their body and light on the bottom. This makes the dogfish harder to see from both above and below – an advantage to avoiding predators and approaching prey.
You can see the countershading in this video is of the Spiny Dogfish (Squalus acanthias). You can also see the characteristic white spots along their back as they dance for the camera.
A fun fact about the Spiny Dogfish is that they carry their young internally and have the longest gestation period for any vertebrate found to date. For us humans, gestation lasts about 9 months. For a spiny dogfish, gestation lasts two years!
After 24 months, the litters of dogfish enter the world. Funny how both dogs and dogfish have groups of young called litters.
When I was a kid, my family went to Biomes – a little aquarium in North Kingstown, Rhode Island. They had a tank full of dogfish sharks and we got to touch them! I remember being a bit nervous; after all, I had never touched a shark before! They felt like suede and they weren’t threatening at all. That was when I realized that sharks weren’t scary monsters. They are however, another incredible ocean creature that needs our attention and action to survive.
Unfortunately, the dogfish shark population has decreased along with many other shark species. You can learn more about the dogfish population and the stocks of other fish through Fish Watch.
If you're ever in North Kingstown, be sure to check out Biomes too. You won't be disappointed.
Video by Sara K. MacSorley
Thanks to University of Rhode Island, Graduate School of Oceanography - Marine Life Science Facility