Biology of the Bumpytail Ragged-

Tooth Shark  (Odontaspis ferox)

Bumpytail Ragged-tooth Shark (Odontaspis ferox)

Field Marks Second dorsal and anal fins smaller than first dorsal fin; first dorsal fin origin closer to pectoral fin bases than pelvic bases; snout bulbously conical relatively long (greater than mouth width); teeth slender and fang-like, usually with 2 or more lateral cusplets on each side of main blade; 2 large anterior teeth on each side of upper jaw, separated from lateral teeth by 2 to 5 small intermediate teeth; Color medium to dark grey above, belly often blotched; young with dusky margins and tips on both dorsal fins and caudal fin, sometimes with darker reddish spots scattered on flanks.
Size Length at birth predicted to be about 41 in (105 cm); average length 5 to 7 ft (1.5 to 2.1 m); maximum size is 12 ft (3.7 m) in length and 710 lb (323 kg) for a female specimen; largest recorded male was 9 ft (2.75 m) long.
Range Cosmopolitan but spottily distributed.
Habitat Deep-water inhabitant of warm temperate and tropical seas; on or near the bottom on continental or insular shelves and upper slopes (has been observed by divers on coral and rocky reefs near drop offs), but also occurs in open ocean; known depth range 43-1,380 ft (13 to 420 m), but possibly as deep as 1 740 ft (530 m) off New Zealand; a specimen was recently caught at a depth of 33-140 ft (10-40 m) in the Sicilian Channel, elsewhere most are caught at depths of 43-300 ft (13-91 m).
Feeding Preys on small teleosts, other elasmobranchs (off southern California, parts of an unidentified ray were observed falling from the mouth of a captured individual), squids, shrimps and other crustaceans (there is an odd reference to a "pillbug" found among the stomach contents of a specimen from southeastern Australia); has been observed swimming amid large groups of baitfish.
Reproduction Almost certainly ovoviviparous; embryonic nutrition probably features oophagy (egg-eating) and possibly embryophagy (womb mate-eating). No data on number of pups (2 - 4?), pupping season, or nursery grounds.
Age & Growth Males reach sexual maturity at a length of about 9 ft (2.75 m), females at about 12 ft (3.6 m); no data on age at maturity or longevity for either sex.
Danger to Humans Potentially dangerous, but has not been implicated in attacks on humans; has on rare occasion been observed by divers, showing no aggression toward them even when approached closely (a large, free-swimming individual was recently photographed underwater in the western Mediterranean)
Utilization Most catches are accidental in gill nets set close to the bottom; an infrequent bycatch in the Sea of Cortez shark fishery, also caught sporadically by setlines off south-west Malta, mostly at night over rocky bottoms at depths of 130-660 ft (40-200 m); in Japan, oil and meat from this species considered inferior to that of the Sandtiger (Carcharias taurus).
Remarks Poorly known shark that may be far more wide-ranging in warm-temperate and tropical seas than current records indicate and seasonally abundant in some regions; confusion with other sharks may be partly to blame for the general lack of biological data on this species; catches should be preserved and reported.

 

There are few things new under the terrestrial sun. But such is definitely not the case in the ocean. One of the most unique and seductive qualities of recreational scuba diving is that virtually any individual applying keen powers of observation and an enquiring turn of mind can see things that no one has before. In doing so, divers can even make fundamental scientific discoveries about the natural world in a manner afforded by few other sports activities.

The Bumpytail Ragged-Tooth Shark is widely distributed, but records of its occurrences are so few and spotty it is all-but impossible to predict where one will next appear. It is typically a deep-water species that is most active at night. As a result, it is rarely seen alive and very little is known of its behavior in the wild. In August 1998, shark biologist Ian Fergusson received via modem what are almost certainly the first underwater photographs of a free-swimming Bumpytail Ragged-Tooth Shark. Taken by Lebanese scuba instructor Walid Noshie in 1993, the photos show that unlike the flabby, distorted, faded, and very dead specimens pictured from time-to-time in the scientific literature the living Bumpytail Ragged-Tooth is a gorgeous creature indeed: sleek and solid, with graceful lines; its body is a handsome charcoal-grey above, shading smoothly to pure white below; and its face is punctuated by spectacular slender teeth and dark, soulful eyes. At long last, it is clear that the Bumpytail Ragged-Tooth Shark is every bit as photogenic as it's better-known cousin, the Sandtiger (Carcharias taurus).

According to Walid Noshi, he and other divers have encountered small aggregations of 11.5- to 13-foot (3.5- to 4- metre) Bumpytail Ragged-Tooth Sharks at the same dive site almost every summer (July-August) since 1979. This locally renowned dive site is called "Shark World", located some 0.6 to 2 miles (1 to 3 kilometres) off the coast of Beirut. The underwater terrain there consists of rocky reef areas and terraces ranging in depth from about 100 to 150 feet (30 to 45 metres), with associated deeper drop-offs and some nearby wrecks. The sharks themselves are neither particularly curious nor aggressive toward divers. Thus, unless provoked, the Bumpytail Ragged-Tooths probably do not represent a significant threat to humans. Given the significant depths involved, however, this is clearly not a dive for the inexperienced or faint-of-heart. But the opportunity to encounter the rare and little-known Bumpytail Ragged-Tooth Shark must be highly seductive to any diving naturalist.

Why do small aggregations of Bumpytail Ragged-Tooth Sharks visit the "Shark World" dive site each summer? Where do they go during the rest of the year, and why? With very limited information to go on, it is difficult to answer such questions. Captures made during early morning and late evening in the Indian Ocean suggest that the Bumpytail Ragged-Tooth Shark may be a vertical migrator, ascending into shallower water at night and returning to the depths before dawn. The nearby drop-offs at "Shark World" may allow these generally deep-water sharks access to the rich feeding afforded by the relatively shallow rocky reefs and terraces at "Shark World". Unfortunately, the diet of the Bumpytail Ragged-Tooth in the Mediterranean as elsewhere is very poorly known. The teeth of this species are less robust and more weakly differentiated than those of its better-known cousin, the Sandtiger. Thus, the Bumpytail Ragged-Tooth probably feeds primarily on small bony fishes, but may also take squids and shrimps when the opportunity presents itself. Unfortunately, feeding is only very rarely witnessed in the wild not because it particularly infrequent, but largely because predation events tend to occur with explosive suddenness. Afterward, particularly in marine habitats, everything returns to 'normal' with deceptive rapidity. Unless a diver happens to be looking in the right direction at the right time, he or she would probably never know anything important had happened.

The reported size of the sharks encountered at the "Shark World" site fall well within the range for sexually mature Bumpytail Ragged-Tooth Sharks males mature at a length of about 9 ft (2.75 m), females at about 12 ft (3.6 m). Since the Bumpytail Ragged-Tooths encountered at "Shark World" include members of both sexes and some individual females bear indistinct scarring on their flanks, fins, and backs, Ian Fergusson and Leonard J.V. Compagno speculate that rather than being primarily a feeding area the site may represent a mating ground for this species in the eastern Mediterranean. If, however, underwater observations at night confirm that the Bumpytail Ragged-Tooths at "Shark World" actively feed, Fergusson and Compagno may revise their conclusion. Alternatively, perhaps further evidence of Bumpytail Ragged-Tooth reproductive activity will eventually be found at "Shark World": signs of fresh, white mating scars on females or perhaps an as-yet undiscovered shallow-water nursery area (where the 3-foot or 1-metre pups are born), just shoreward of the "Shark World" site. Such discoveries, as well as accounts of encounters with Bumpytail Ragged-Tooth Sharks from here or elsewhere on the globe, should be reported to an ichthyologist or other marine researcher, especially one with a particular interest in sharks.

Not that long ago, the chief prizes with which divers could return to the surface were food, hunting trophies, or tall tales of undersea adventure. There is still adventure aplenty to be had in the ocean, but for many divers the nature of the prizes to be brought back has changed dramatically. Armed with an understanding of what to look for and by carefully reporting and recording their underwater discoveries, divers are in a powerful position to significantly increase our understanding of not only rare or unusual sharks, but of the ocean in general. There are few adventures that can offer such rich rewards.

 

ReefQuest Centre for Shark Research
Text and illustrations R. Aidan Martin
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