When it comes to sharks, most of us are familiar with the big toothy sharks. Great white sharks, tiger sharks and bull sharks, also known as the “Big Three” and receive the most media attention. Yet sharks are extremely diverse in shape, size and ecology and many species are little known or understood by scientists. In this blog we will feature the strange, the arcane and the sublimely strange species of sharks, beginning with sharks in the San Francisco Bay, and off the Pacific Coastline.
One unusual specimen living in the deeper waters off our coast is known as the Frill Shark (Chlamydoselachus anguineus).
Also called the Lizard shark, or Scaffold shark, this is little-known, deep water shark’s dating as far back as the late Jurrasic (150 Million years ago). Called primitive by some, the shark is considered basal, or a living fossil. These sharks have six gill slits, which each possess a distinctive frilly margin, giving it the common name. It is considered to be most closely related to the sevengill sharks, another ancient lineage living off our coastline and in the San Francisco Bay.
The frilled shark has been observed on continental margins and deep sea vents across the Atlantic and Pacific Oceans. Locally, this relatively rare species is found over the outer continental shelf and the upper continental slope, outside the Farallon Islands. Generally a bottom dweller, there is evidence of upward movements that may be associated with feeding. Some specimens have been brought up as bycatch in deep water trawls nearly a mile deep.
The species name anguineus, derives from the Latin word for snake-like. The genus name is Greek, chlamy (frill) and selachus (shark). The body is elongated and supple and the head is like a lizard with a very large mouth armed with multiple rows of sharp, three-pronged teeth numbering as many as 300. The long, extremely jaws enable it to swallow prey whole, and its rows of curved back, hook-like teeth make it difficult for the prey to escape once bitten. Its prey includes squid, bony fish and small sharks.
These sharks are ovoviviparous, with eggs hatching internally and birthed live and fully functional. Litter sizes vary from two to fifteen. The gestation period may be as long as three and a half years, the longest of any vertebrate. Because of these characteristics, the International Union for Conservation of Nature has assessed it as Near Threatened, since even small catches may deplete its population given its low reproductive rate.
Follow our San Francisco Bay Shark blogs to learn about other sharks and share.copyright 2014 David McGuire Shark Stewards is dedicated to conserving our ocean resources by saving sharks. Shark Stewards is a non-profit project of Earth Island Institute