The Port Jackson Shark, Heterodontus portusjacksoni
… is a common inhabitant of the continental shelf of Southern and Western Australia. It feeds on benthic invertebrates, primarily echinoderms. The teeth of the Port Jackson Shark are unusual. They are not serrated, and the front teeth have a very different shape from those found at the back of the jaws. The anterior teeth are small and pointed, whereas the posterior teeth are broad and flat. The teeth function to hold and break, then crush and grind the shells of molluscs and echinoderms. This shark is considered harmless to people, but can deliver a painful nip when provoked.
Phylogenetic studies based on morphology have generally placed the goblin shark as the most basal member of the order Lamniformes, known as mackerel sharks. Studies using genetic data have also supported a basal position for this species.
The family Mitsukurinidae, represented by Mitsukurina, Scapanorhynchus, and Anomotodon, dates back to the Aptian age of the Cretaceous period. Mitsukurina itself first appears in the fossil record during the Middle Eocene extinct species include M. lineata and M. maslinensis.Striatolamia macrota, which lived in warm shallow waters during the Paleogene, may also be a Mitsukurina species. As the last member of an ancient lineage, and one that retains several “primitive” traits, the goblin shark has been described as a “living fossil”…
Mission: To allow trained SCUBA divers to log encounters with Sevengill Sharks
…1. Be SCUBA certified 2. NEVER endanger yourself around sharks to have an encounter. NEVER touch a shark. If it exhibits what appears to be aggressive behavior, get out of the water immediately. 3. If you think you’ve seen or encountered a Sevengill shark, go to [www.sharksonline.net] and log your encounter there first. 4. Then, come here and log your encounter here. The Shark Observation Network is the primary database. For more information on this project, see: http://sevengillsharksightings.org/
The Gulf Torpedo (Torpedo sinuspersici) is a ray distributed across the western Indian Ocean. It has a distinctive coloration of a brown base and cream colored spots. It also catches prey using a trait that is usually associated with another type of sea creature. It wraps around prey and sends an electric shock through it.
illustration from Histoire physique, naturelle, et politique de Madagascar, by Alfred Grandidier, 1850
The vast sandy channels and grassy flats of Brazil’s Amazon estuary may be the last, best hope for the beleaguered largetooth sawfish (Pristis pristis) in the Atlantic Ocean. The swimmer, known for its long, tooth-edged snout that looks like some alien saw blade, is one of the world’s most threatened marine creatures, a victim of overfishing and habitat loss.
Though this could be the largest freshwater fish on the planet, accounts of its existence only emerged in Thai newspapers in the early 1980s. It’s exceedingly rare to see one, in part because it destroys all but the strongest fishing rods and lines. Even if you have the right equipment, the giant freshwater stingray tends to take exception to being hunted and buries itself in the river bottom when hooked.
In 2010, 15 anglers working in shifts reportedly spent six hours reeling one in, which either says something about the stingray’s strength or the group’s collective fishing skills. The fish can drag boats for miles, and even pull them under…
… is a species of skate in the family Rajidae, found from Nova Scotia to North Carolina. Little skates prefer sandy or gravelly habitats from the shore to a depth of 90 meters (300 ft), though they have been caught as deep as 329 meters (1,080 ft). This species typically measures 41–51 cm long (16–20 in) long, but may reach 54 cm (21 in) long.
Little skates are more active at night and spend much of the day buried in sediment, usually near specific landscape features such as depressions excavated by other animals. They employ a curious mode of locomotion, dubbed “punting” by the first scientists to document it, to move over the sea floor. The forward lobes of the pelvic fins are modified into leg-like structures called “crura” (singular “crus”), containing three flexible joints and modified skeletal and muscular elements. The little skate pushes off the substrate with both crura and then glides a short distance on its wings while repositioning the crura for the next push. The crura are also used as pivots when the skate needs to turn. It has been speculated that using the pelvic fins in this manner assists in hunting, by reducing water turbulence that might alert the prey or distort the ray’s electroreception…
The Japanese roughshark is a rare species of shark in the family Oxynotidae, known only from a handful of specimens recovered from Suruga Bay and the Enshunada Sea off Japan. It is a benthic species that occurs at a depth of 150–350 m. This shark is caught (and discarded) as by-catch by bottom trawlers throughout its entire limited range, and may be threatened given the declines in other bottom deep sea species in Suruga Bay.
This species grows to 64.5 cm long. It is similar to other rough sharks in having a stout, high trunk, a dorsally depressed head, and two sail-like dorsal fins with deeply embedded spines. The snout is short, with large nostrils whose lateral and medial apertures are separated by a thick nasal flap. The eyes and spiracles are oval in shape. The five pairs of gill slits are very small and vertical. The mouth is small, with thick, fleshy lips; the teeth in the upper jaw are narrow, erect, and smooth-edged, while those in the lower jaw are broad, blade-like, and smooth-edged. Only one row of teeth in the lower jaw are functional…
Thornback rays, Raja clavata, locate their prey with a very acute sense of smell. Water enters two openings on the snout (the nares) and passes through the olfactory sac which is lined with folded olfactory lamellae that provide increased surface area for molecule-receptor interactions. Molecules dissolved in the water bind to neuroreceptors in the olfactory lamellae to convey chemosensory information to the brain.
A new species of “walking” shark has been discovered in a reef off a remote Indonesian island.
These sharks don’t always rely on “walking” to move about — often, they only appear to touch the seafloor as they swim using their pectoral and dorsal fins in a walklike gait, said Fahmi (who only goes by one name), a shark researcher at the Indonesian Institute of Science who wasn’t involved in the study describing the species. In the video of the newfound walking shark, however, the animal is clearly touching the seafloor.
The shark grows up to 27 in (70 cm) long and is harmless to humans, said Mark Erdmann, a marine biologist and adviser with Conservation International who was also a co-author on the study describing the species. The animal has been dubbed Hemiscyllium halmahera, named after the eastern Indonesian island of Halmahera where it was found. Sharks in its genus (the taxonomic group above species) are also known as epaulette sharks…
In honor of this past shark week and shark fest, here is one of my favorite chondrichthyes (class of cartilaginous fish). The bowmouth guitarfish is a type of large ray that lives in tropical waters anywhere from South Africa to Western Australia. These large, heavy fish can grow up to about 9 feet and weigh about 300 lbs. The dorsal skin is covered in small, rough bumps, and in some areas, thick thorns.
These are mostly nocturnal hunters, feeding on bony fish, crustaceans and mollusks. It uses the rounded bands of flattened teeth to crush the shells and bodies of its prey.
This ray is vulnerable due to shark finning, over fishing, bycatch, and sport fishing. Some fishermen kill them because their large thorny bodies can cause damage to their nets.
Please help raise awareness of over fishing and finning of all species. You can help conservation!
Waters off of France and the U.K. were once teeming with sharks, many of which would have looked like today’s range of shark species.
Samples of Late Cretaceous rock from the region turned up remains of 96 different types of prehistoric sharks, 18 of which represent new species, a paper in the Journal of Systematic Paleontology reports.
The sharks lived from 100 to 72 million years ago, but many looked like modern sharks.
"If you were to see a Cretaceous shark, I am pretty sure that it would look no different from one in an aquarium," senior author David Ward of The Natural History Museum in London told Discovery News. "Shark body design stabilized about 140 million years ago and, other than a few families that have suffered from extinction, remains the same now."…