With Spring and Sevengill shark season right around the corner,
Ocean Sanctuaries has two citizen science shark monitoring programs for California divers to choose from.
The first project is a partnership with National Geographic, called ‘Sharks of California’. Any
non-Sevengill shark species can be logged there, using National Geographic’s ‘Fieldscope’ citizen science data collection tool at:
http://sharksofsandiego.fieldscope.org/v3. A couple weekends ago, at the Coronados Islands, south of San Diego, a diver encountered a juvenile Great White and uploaded her photo to ‘Fieldscope,’ for a grand total of 3 Great White sightings now documented in that program by California divers–along with 3 Hammerhead sharks and several other species.
A second citizen science shark monitoring program, called ‘The Sevengill Shark ID Project’, allows California divers to upload photos of their Sevengill encounters.Their photos of Sevengill sharks will be analyzed by a pattern recognition program to determine which individual sharks are returning from year to year. Go to:
http://oceansanctuaries.org/sevengillshark/ and click on Participate–>Report an Encounter – it’s the third tab from the left at the top of the page.
Remember to take your camera diving with you – at least one photo is required for each program.
Sevengill sharks are named for having seven gill slits on either side of their bodies, and reach lengths of at least 9 feet with an average length of about 5 feet. They weigh up to 240 pounds and are known to live as long as 49 years. Sevengills are thought to reach sexual maturity when they reach 5 to 7 feet in length. They are large, active sharks with wide heads, small eyes, short blunt snouts and fusiform (spindle-shaped, wide in the middle, tapering at both ends) bodies. They have small single dorsal fins that are set far back over their pelvic fins. Their anal fin is notably smaller than their dorsal fin.
Sevengill sharks have a tooth “count” of 15-16/13 (upper/lower jaw). Their teeth are wide, large and comb-shaped in their lower jaws, which they use to tear and cut into prey. The teeth in their upper jaws are sharp and jagged, which are used to hold onto prey.
In color, Sevengills are generally reddish-brown to silvery-gray or olive-brown with numerous small black spots on their bodies and fins; their undersides are a light or cream color. This counter-shading is a common type of camouflage that helps the sevengill blend into the sea bottom or ocean depths when viewed from above and the lighter surface waters when viewed from below. This counter-shading is also common among many pelagic species of sharks and fishes as well as other marine species.
As always, use common sense and caution when around sharks and never endanger yourself to take a photo. The ocean will always be there tomorrow!
