May 2015 Shark of the Month: Broadnose Sevengill
Name: Broadnose Sevengill Shark Scientific Name: Notorynchus cepedianus
Key Features: Just like its name implies, the Broadnose Sevengill shark has 7 gill slits instead of 5 gill slits, like most other shark species. This shark is part of the order Hexanchiformes, also called “cow sharks,” which contains the most primitive shark species living today. All of the sharks found in this order have between 6-7 gill slits, and only one dorsal fin that is located way back by the pelvic fins. The Broadnose Sevengill is also usually grey or brown in color, and covered with small black or white spots and can range between 5-10ft in length. To help differentiate between the Broadnose Sevengill and the Sharpnose Sevengill- just look at their heads, for they are both very aptly named! The Sharpnose has an acutely pointed head while the Broadnose has a more blunt, broad head. Where it’s found: Broadnose Sevengill sharks have a wide-ranging distribution of temperate, in-shore waters (except the North Atlantic and Mediterranean Sea). They are a demersal species, which means they like to spend their time on or close to the seafloor bottom, and can be found in shallow waters of bays or estuaries. Other Hexanchiformes live in cold, deep water, which makes the Broadnose Sevengill shark the most studied of the cow sharks. Diet: Broadnose Sevengills are opportunistic predators, which means that they will feed on almost anything, including rays, dolphins, porpoises, seals, sea snails, and even rats. They are incredibly adept predators and will work together to hunt in packs to capture large prey like seals and sea lions, and trap them in shallow areas. Although Broadnose Sevengills are usually found slowly cruising the seafloor, they can use sudden bursts of speed to catch prey like Leopard Sharks off of California. Conservation Status: IUCN Red List- Data Deficient globally, and Near Threatened in the Pacific Northeast. “Data Deficient” means that little or no information is available on the abundance and distribution of the species Threats: Populations of Broadnose Sevengill sharks were fished extensively in the northeast Pacific in the 1930s and ‘40s. The sharks were targeted for their meat and liver oil, although recently the species is mostly caught as bycatch by commercial fisheries. A natural threat to the Broadnose Sevengill is the Great White Shark, as their habitat and distribution overlaps extensively, and some Sevengills have been spotted with large scars resulting from run-ins with the much larger predator. FINtastic Fact: Broadnose Sevengill sharks have comb-shaped teeth in their lower jaw and sharp, jagged teeth in their upper jaw. When they are biting into their prey, the lower teeth help anchor the prey while shark thrashes its head back and forth to use the sharp upper teeth to saw off pieces of the prey (like using a fork and knife).