sevengill-shark

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Broadnose Sevengill Shark (Notorynchus cepedianus)

The Broadnose Sevengill Shark is the only extant member of its genus. Whereas most other sharks have 5 gill slits, sevengill sharks are recognisable because of its 7 gill slits.

Like many other fish, the shark uses counter shading as a of camouflage. Its dorsal surface is silvery grey in colour, which allows it to blend with the dark waters beneath it when viewed from above. Conversely, its ventral surface is light in colour, matching the sunlit surface when viewed from below.

An opportunistic predator, the broadnose sevengill preys on a great variety of animals. It has been found to feed on sharks, rays, chimaeras, cetaceans, pinnipeds, bony fishes, and carrion. These sharks occasionally hunt in packs to take down larger prey, using tactics such as stealth to succeed.

Information: Wikipedia, Images: Robertson, D Ross

Shark swap!

Two in…

We recently added two female sevengill sharks to the Monterey Bay Habitats exhibit. They were collected from the San Francisco Bay, a sevengill shark hotspot. Here are their stats:

She Shark 1

  • 6.7 feet - 2.01 meters
  • 83 pounds - 37.6 kilograms

She Shark 2

  • 5.3 feet - 1.64 meters
  • 42 pounds - 19.2 kilograms

… And two out!

The new girls are replacing two other sevengills that were just returned to the San Francisco Bay, as a part of a long-term scientific monitoring program.

By measuring how fast these animals grow in our exhibit—where we know how much they’ve eaten and how cold the water was—we can assess how healthy their food supply is in the wild, if we find the sharks again. And by using satellite tags, we’ve found that our sevengill sharks can go on massive migrations up and down the West Coast!

Sevengills are usually with us for a year or so before they head back to the ocean. Before your next trip, you can catch them on our new shark cam.

Learn more about the research the Monterey Bay Aquarium is conducting to help the conservation of the ocean (and its sharks)!

Seven thumbs up for sevengills!

I am so lucky. I have been recruited to help during some of our shark training sessions. I am responsible for bridging them when they successfully take food from the target pole. AND I get to desensitize them to tactile behaviors. So basically when a shark swims by the surface I reach down and touch it gently along its back and hope that it doesn’t freak out or thrash. These types of behaviors are important for the sharks to be comfortable with so that they aren’t as stressed during their yearly physicals.

For my anonymous shark training question. We start our shark target training sessions by ringing a bell underwater 20 times. My coworker Riah is the one holding the pole. She puts the target pole, that has food on the end, in front of the Sharks. And if they choose to take the food then I ring the bell 3 times and record which shark ate. It’s really basic training but the reasons we do it are to help us catch these large creatures for their yearly physicals. When they associate the bell with food we can use it to call them over. When they associate the pole with food we can use it to lead them into the smaller attached tank to give us better access to them.

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We have 6 Sevengill Sharks swimming around our shark tunnel. They get target fed every Tuesday and Saturday, and it’s not an easy process. It’s a three person job. The feeder is in the middle and the two divers on the outside are fenders. It’s the fenders job to keep sharks and other fish away from the person in the middle with the food. And also to keep the Sharks from coming overhead. All the divers heads have to be constantly on a swivel and moving around looking for potential sharks to feed and situations to fend off. The dive lasts 30 minutes. There is also an observer on the public side watching the divers, giving them signals, and recording what sharks ate how much.

This is the first field observation of intestinal eversion by a shark, the broadnose sevengill shark (Notorynchus cepedianus) at False Bay, South Africa.

Intestinal rinsing via eversion through the cloaca has been documented in a number of sharks that possess a scroll or conicospiral type of valvular intestine aka spiral valve. This valve was first described by Marcus Aurelius Severinis in 1645 and is the lower part of a shark’s intestine that is twisted to allow a greater surface area for digestion and increased nutrient absorption.

Intestinal eversion has been documented in elasmobranch and also in sawfish (Pristis pectinata), all of these observation occured with individuals held in captivity in aquaria, just one time, one case of eversion has been documented in the field, wich was also notable, because it ocurred in a manta ray (Manta birostris)