Are Sharks The Devil
Ronna Bordelon
French naturalist Charles Alexandre Lesueur described the sand devil in an 1818 volume of Journal of the Academy of Natural Sciences of Philadelphia. Previously, it had been regarded as the same species as the European Squatina squatina. Lesueur based his account on an adult male 1.2 m (3.9 ft) long caught off the eastern United States, and named the species in honor of Andr Marie Constant Dumril.[2]
Phylogenetic analysis, based on mitochondrial DNA, has concluded that the sand devil and the Pacific angel shark (S. californica) are sister species. The two of them in turn form a clade with other angel sharks found in the Americas. Molecular clock estimation has timed the divergence of S. dumeril and S. californica at c. 6.1 Ma, around the time that the Isthmus of Panama formed. The rise of the Isthmus likely split the ancestral angel shark population, leading to their becoming separate species.[3]
The sand devil has a flattened, moderately narrow body with greatly enlarged pectoral and pelvic fins. The skin folds along the sides of the head have smooth margins, without lobes. The large eyes are placed on top of the head and have prominent spiracles behind. The nostrils bear thin, pointed barbels with smooth or slightly fringed margins. The wide mouth is positioned terminally on the head. The jaws contain 10 upper and 9 lower tooth rows on each side, with toothless gaps at the middle. Each tooth has a broad base and a single pointed cusp with smooth edges. There are five pairs of gill slits located on the sides of the head.[4][5]
The sand devil is found in the northwestern Atlantic Ocean from Massachusetts to the Florida Keys, where it is fairly common. It also occurs in the northern Gulf of Mexico, and there are additional unconfirmed records from Cuba, Jamaica, Nicaragua, and Venezuela. The southern extent of its range is uncertain due to confusion with the disparate angelshark (S. heteroptera) and Mexican angelshark (S. mexicana). Because they inhabit deep-waters and because of their low commercial value the effort put into data collection is low, as with many species under these circumstances. Although their appearances are fragmented they still are classified under large broader spaces due to the lack of research done. As a result, ranges of deep-water shark species are often considered continuous across broad expanses despite records of occurrence, in many cases, being spatially fragmented. [6] This bottom-dwelling shark is found over sandy or muddy bottoms on the continental shelf and slope.[4]
Off the eastern United States, the sand devil has been documented to migrate seasonally. In the summer, it moves towards the shore to depths of less than 35 m (115 ft), and many can be found in water only meters deep. During fall it can be found inshore, down to a depth of 90 m (300 ft). In winter and spring, it is found around the outer continental shelf at depths greater than 90 m (300 ft); individuals have been recorded as far as 140 km (87 mi) from land and 1,290 m (4,230 ft) deep.[4]
Though not normally aggressive towards humans, the sand devil can inflict serious wounds if provoked. Its common name refers to its habit of snapping vigorously at fishery workers when caught, and even out of the water it is capable of lunging upwards to bite.[4][5] This shark is caught incidentally in bottom trawls operated by commercial fisheries targeting other species. It is edible but seldom brought to market.[4] The International Union for Conservation of Nature (IUCN) presently rates this species as least concern.[1]
I am an open water swimmer. Like a few hundred others at the South End Rowing and the Dolphin Club, I routinely swim in the Bay year round, without wetsuit. But there are swimmers and there are Swimmers. An arcane group of athletes around the globe take on extreme athletic challenges, crossing large portions of open water without protection. The English Channel is a well known passage, but there are many lesser known swims with greater risk and more extreme conditions.
Known as the Ocean 7, elite open water swimmers take on crossings like the Cook Straits, the Molokai Channel and Tsugaru Straits of Japan. Not part of the Ocean 7, but what many consider the most difficult of ocean passages is called the Farallon Island Channel. This swim, now sanctified by the Farallon Island Swim Association combines cold water, strong currents, stinging jellies and the presence of great white sharks.
The first two solo crossings from the island to the shore were in 1967 as part of a friendly rivalry between two swimmers from the Dolphin Club. Starting at South East Farallon Island (SEFI) Dolphin Club member Lt. Col. Stewart Evans completed the first crossing to the coast, finishing at the beach near Bolinas in 13 hours, 44 minutes. In early September, few weeks later Ted Erikson started swimming at SEFI and swam all the way to the Golden Gate Bridge in 14 hours, 38 minutes. Since then, a few relay teams have made the trip across in both directions, but until June 2014 no one has made a complete solo crossing. This June, an accomplished distance swimmer, Coloradan Craig Lenning made the attempt to cross the Gulf to the Gate. Currents off Point Bonita caused Craig to miss the bridge but he successfully landed at Muir Beach in 15 hours, 47 minutes.
My friend Joe Locke has long had his eyes on this goal. A soft spoken, hulk of a man, Locke has swum the English Channel and many other distance challenges. When asked to advise him on sharks and the islands last year, I gladly joined his team to help escort him safely across the Gulf of the Farallones.
One of the great challenges of this swim are the conditions off our coastline. Coastal upwelling brings up deep nutrient rich cold water creating an abundance of life and the conditions for the summer fog we know so well. Storms from the Aleutians and localized northwest winds generate large swells, wind waves and strong currents. And then, there are the sharks.
Everyone talks about the sharks but few see them. In fact, most of the large white sharks of are still offshore in early summer, heading back home on their migration from the White Shark Cafe.
Although some white sharks stay in the region year round, the odds of a shark encounter get higher as the water warms and the season progresses towards Sharktober. Surfers, swimmers and divers have experienced encounters along our coastline. The risk is always present, yet the odds of encountering a shark are lower than other wildlife. In fact, more swimmers get bit by Sea Lions locally than Sharks. Still, the sharks are here and its part of the risk we take surfing, diving and swimming in the Red Triangle. Swimmers considering the Farallons passage must weigh water temperature and weather against the increase risk of encountering a white shark as the Sharktober season progresses. It is not advisable to attempt swimming or even kayaking around South East Farallon Island when the large sharks are present in numbers roughly between August and December.
Joe plunged into the darkness at the SEFI buoy a shade after midnight. The sea lions and common murrres serenaded us as the 34 foot Hyperfish support boat followed behind as he immediately stroked east away from the rocky island. His stroke rate was high, in the mid eighties, but the water temperature at 53 and calm seas boded well once he settled in. He soon left the odor of sea lions and murres behind but drifted over and through patches of stinging nettles.
For the first few hours Joe swam steadily between two and three miles in an hour. Every 40 minutes we fed him his home-brewed super food tossed out in water bottles on a line. No sharks came to visit, but a Sea Lion followed him for an hour, swimming beneath and bumping him from behind.
Join Shark Stewards Director David McGuire on wildlife expeditions to the Farallon Islands in the fall. Want to learn more or help support our work fighting shark finning or the shark fin trade please visit www.sharkstewards.org.
Some animal activists say that many of the television shows about sharks portray them to be more vicious than they really are. Sharks rarely have been known to prey on humans. Many attacks are thought to occur because the shark mistakes a person for something that it normally eats.
It is possible to discover a new species out in the field, but it is more likely to occur within the four walls of a museum. Curators and biologists alike will find treasure troves here, many containing specimens that have long since disappeared from our blue planet. I would be lying to you if I said identifying a new animal was an easy or quick task. In fact, the discovery is often the result of a niggling thought in someone's head.
Even though many of them go to great lengths to find new species, sometimes they make their presence known to you. Such was the case in 2011 when, during his volunteer work at the Western Australian Museum (WAM) in northwestern Australia, researcher Brett Human found an unidentified shark egg. The shape was unique, with the dorsal and ventral surfaces consisting of a series of longitudinal, T-shaped ridges. Only one other shark species had strong T-shaped ridges like those on this egg, the egg cases of the dusky catshark (Bythaelurus canescens). Deep-sea sharks with cat-like eyes and dark coloration that live in the Southeast Pacific, Human realized an embryo was inside... and was dumbfounded. It did not look like a dusky catshark.
But scientists recently found two more ridged egg cases identical to what had been found by Human in 2011 sitting in the Australian National Fish Collection (CSIRO). CSIRO researchers checked their collection database to see if any other Apristurus specimens had been found in the original collection area. There was - a female South China catshark (Apristurus sinensis), and she was pregnant! Upon cutting into her, a single egg case that looked like the others was discovered inside, where a well-preserved late-term embryo confirmed that this species belongs to the genus Apristurus.
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