These sharks are recognized by divers as more annoying than dangerous. The 3' to 4' spiny dogfish has an unnerving habit of veering abruptly toward divers, but it does not attack people. It eats fish, not the seals and sea lions that a larger shark might occasionally mistake a human for.
|Spiny dogfish shark|
In addition to its sharp teeth, the spiny dogfish has two slightly venomous spines on its back, one in front of each fin. If one of the spines punctures flesh, a gland releases venom that can create a painful wound in humans--this is most likely to happen when one of these sharks is hauled aboard a boat.
Spiny dogfish mamas carry their 4 to 6 young for almost two years--probably the longest of any vertebrate. She doesn't pass along nutrients to them that entire time, however. Each hen-sized egg has its own large yolk sac from which the embryo takes nourishment. As the young develop, their sharp spines are covered with pads of tissue that protect the mother.
These sharks were once the most abundant shark species in the world, but you know how this story goes. First we overfished their food species, then we overfished spiny dogfish themselves. Some fishery management policies are now in effect, but it remains to be seen whether the species can recover.
Have you ever seen a shark--spiny, driveway, or otherwise?