Tail of Piked dogfish
Species: S. acanthias
Piked dogfish has a “Heterocercal tail”, that is having the upper lobe larger than the lower with the vertebral column extending into the upper lobe. It’s tail swings from side to side, it creates twice as many jets of water as other fishes’ tails, smoothing out the thrust and likely making swimming more efficient. Piked dogfish do this by stiffening the tail midswing, a strategy that might one day be applied to underwater vehicles to improve their performance.
About the Animal
The piked dogfish is a compact shark species reaching a maximum of 39 inches in males and 49 inches in females. With a slender body and pointed snout. Their skin is grey to brown on top and becomes increasingly paler, or even white, on the belly with small white spots running down each side of the body. The spiny dogfish is a highly migratory species–one individual tagged in Washington made a 5,000-mile journey to Japan. The spiny dogfish also breaks records when it comes to gestation. These sharks have the longest pregnancy of any vertebrate at 22 to 24 months, or two years! Eggs develop in the female, gaining nutrients from yolk sacs, and live young are born at 20 to 33 centimeters. Even at a young age, newborn spiny dogfish pups may hunt fish two or three times their size.