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.
The spotted ratfish aka spotted chimera, Hydrolagus colliei, can be found off the coast of California to depths of about 3,000 feet. Its common name comes from the white spots that cover its body and its pointed rat-like tail. These fish are chimeras, meaning they have characteristics of bony fishes and sharks, from which they descended millions of years ago.
While exploring the debris slope of the collapsed side of the underwater volcano Kick’em Jenny near Grenada in the Caribbean, the Nautilus expedition crew had a surprising find of a large cold methane seep and rich biology around it. Here are a few of the amazing creatures we spotted there and more can be found at http://www.nautiluslive.org.
Shovelnose Chimera, swimming sea cucumber, deep sea octopus, unidentified species of Snailfish.
Chimaeras are perhaps the oldest and most enigmatic groups of fishes alive today. Their closest living relatives are sharks, but their evolutionary lineage branched off from sharks nearly 400 million years ago, and they have remained an isolated group ever since. Like sharks, chimaeras have skeletons composed of cartilage and the males have claspers for internal fertilization of females.
Unlike sharks, male chimaeras also have retractable sexual appendages on the forehead and in front of the pelvic fins and a single pair of gills. Most species also have a mildly venomous spine in front of the dorsal fin.
Chimaeras were once a very diverse and abundant group, as illustrated by their global presence in the fossil record. They survived through the age of dinosaurs mostly unchanged, but today these fishes are relatively scarce and are usually confined to deep ocean waters, where they have largely avoided the reach of explorers and remained poorly known to science.
Chimaeras are the only vertebrates to retain traces of a third pair of limbs.
New Hammerhead Shark Species Found Off South Carolina
by Douglas Main
When new species are found near populated areas, they are often small and inconspicuous, not, for example, a hammerhead shark.
But that’s exactly what a team of researchers discovered along the coast of South Carolina. The new species looks virtually identical to the scalloped hammerhead, but is genetically distinct, and contains about 10 fewer vertebrae, or segments of backbone, new research shows.
The new species, named the Carolina hammerhead (Sphyrna gilbert), gives birth to shark “pups” in estuaries near the shore off the Carolinas, according to a study published in August in the journal Zootaxa…
Spiky-Headed Sharks Survived Mass Extinction, Surprising Scientists
An exotic, ancient shark thrived into the age of dinosaurs, study says.
by Dan Vergano
A family of small sharks—some of which had spiky heads—cruised the ancient seas for far longer than scientists had suspected, surviving to about 120 million years ago. Their surprising survival suggests that deep oceans sheltered predators during past mass extinctions.
The giant prehistoric shark Megalodon is one of the few animals to be identified by its species, rather than its genus, name: technically, this predator is known as Carcharodon megalodon, which places it in the same family as the modern Great White Shark. However, not everyone is convinced that this fearsome shark was a direct ancestor of the Great White, hence its popular name Megalodon.
Until a better candidate comes along—which doesn’t seem likely—Megalodon stands as the biggest shark in earth’s history, a true apex predator that counted everything in the ocean as part of its ongoing dinner buffet, including whales, squids, fish and dolphins (there’s some speculation that Megalodon may even have preyed on Leviathan, a giant, prehistoric sperm whale announced to the world in 2010…
Dive 12, August 13, Northeast U.S. Canyons Expedition 2013
A chimaera swims lazily a couple meters above the seafloor in Lydonia Canyon. Chimeras, sometimes called Ghost Sharks or ratfishes, are a group of cartilaginous fishes, elasmobranchs, along with sharks and rays. Many species, such as this one, are dwellers of the deep ocean.
Off of the Northeast US Canyons the Okeanos Explorer found a Greenland Shark! These sharks can be between 8-16ft long and weight 880lbs. This shark is normally found in Northern Atlantic waters, but has recently been found as far south as the Gulf of Mexico. Scientists have attributed this wide range of habitat to the fact that deep sea environments, even in warmer environments, resemble the natural habitat of the Greenland Shark.
10 More Cool Sharks You Probably Don’t Hear Much About During Shark Week
So I know that Shark Week is over now, but I couldn’t just stop at 10, so here are 10 more!
Angel Shark (Squatina) There are 23 different species of angel shark and all live in shallow, warm seas, though some migrate to warmer waters during the summer. Most types grow to a length of 5 ft (1.5 m). They hunt at night in their own territories. Unlike rays, they have sharp teeth for feeding on shelled prey and small fish. They disguise themselves from prey by covering their bodies in sand and often having sandy-colored skin. An angel shark is hard to see as it lies on the seabed. Its body is so flat that it appears no more than a low mound in the sand. Unlike a ray, it uses its tail rather than its large fins to swim. Read more about this shark…(read more)