Pristiophorus cirratus

Geographic Range

Pristiophorus cirratus is found in the waters around southern Australia’s outer continental shelf, and is endemic to that region. This includes the eastern portion of the Indian Ocean and the southwest portion of the Pacific Ocean. They are found in the area described by the latitudes 20° to 41° south and longitude 112° to 150° east.

• Biogeographic Regions
• indian ocean
  • native native
• pacific ocean pacific ocean
  • native native

Habitat

Longnose sawsharks prefer a variety of marine habitats including the open sea and coastal regions. They are typically found at depths below 40 meters.

• Habitat Regions
• tropical tropical
• saltwater or marine saltwater or marine

• Aquatic Biomes
• pelagic pelagic
• benthic benthic
• coastal coastal

Physical Description

Pristiophorus cirratus is characterized by a long, thin, and flattened snout. The snout is lined with alternating long and short teeth. Unusual nasal barbels protrude about halfway down the snout. Near the barbels are the ampullae of Lorenzini, which are specialized organs for detecting electrical fields. Two dorsal fins are present, with the second being slightly smaller than the first. They lack an anal fin. Five gill slits are present on each side of the head, while most sawsharks have gills on the bottom of the head. The upper body is a blotchy combination of dull yellow, grey, and brown.

• Other Physical Features
• ectothermic ectothermic
• heterothermic heterothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger

Development

Longnose sawsharks are born in litters of 3 to 22 individuals. They are born with their teeth folded back, which mostly likely is an adaptation to prevent possible injury to the mother during the birthing process. The teeth straighten shortly after birth. Sawsharks are born fully developed, looking like smaller versions of adults. Newborn sawsharks are generally 31 to 34 cm in length. Sawsharks do not undergo a metamorphosis and exhibit determinate growth.

Reproduction

Longnose sawsharks breed seasonally. It is unknown if they are monogamous or promiscuous. It is unknown what affect mating behavior has on social structure.

Longnose sawsharks breed once every two years, and most breeding occurs in coastal areas. Each breeding season yields an average of 10 young (range of 3 to 22). The gestation period for longnose sawsharks is approximately 12 months. Longnose sawsharks are ovoviviparous, meaning that the eggs develop within the mother's body and then hatch within the mother before they are released.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • internal internal
• ovoviviparous ovoviviparous

In the pre-birth stage, while the young are still within the womb, nourishment and provisioning are provided by the mother. In the post-birth stage, the parents provide food and protection. The exact duration of parental investment is unknown, but it is complete before the individual's next breeding season.

• Parental Investment
• pre-hatching/birth
  • provisioning
    • female
  • protecting
• pre-weaning/fledging
  • provisioning
  • protecting

Lifespan/Longevity

Longnose sawsharks have been known to survive for up to 15 years in the wild. Lifespan in the wild is often limited by trawl fishing.

Behavior

Longnose sawsharks are motile. Little is known about their social structure, but they do form schools. A notable behavior of longnose sawsharks is the use of their snouts (lined with sharp teeth) to side-swipe their prey. Longnose sawsharks are generally sedentary.

• Key Behaviors
• natatorial natatorial
• motile motile
• sedentary sedentary
• solitary solitary

Home Range

Longnose sawsharks do not travel extended distances. Even if travelling to breed, their home range rarely exceeds 100 square kilometers.

Communication and Perception

Longnose sawsharks communicate using sight, touch, and electric signals. They perceive their environment with mediocre eyesight, use their barbels to touch the ocean floor, and use their ampullae to sense electrical fields. They communicate with other animals visually and use their barbels and ampullae when searching for prey.

• Communication Channels
• visual visual
• tactile tactile
• chemical chemical
• electric electric

• Perception Channels
• visual visual
• tactile tactile
• chemical chemical
• electric electric

Food Habits

Longnose sawsharks feed on bony fish ,including cornet fishes ( Fistularia ), shrimp , small squids , and various crustaceans . Longnose sawsharks uses their barbels and snout to detect prey on the ocean floor, and then immobilize their prey by hitting it with a side-swipe of their snout, which is lined with sharp teeth.

• Primary Diet
• carnivore carnivore
  • piscivore piscivore
  • eats non-insect arthropods
  • molluscivore molluscivore

• Animal Foods
• fish
• mollusks
• aquatic crustaceans

Predation

The main anti-predator adaptation of longnose sawsharks is their coloration. Their blotchy grey and brown markings help them blend in with the ocean floor. Human beings are the main predator of longnose sawsharks, although larger sharks are occasional predators. Humans have severely damaged shark populations due to commercial fishing.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

Longnose sawsharks are not a keystone species, although their absence would have an impact on creatures living on the ocean floor because they serve as prey for longnose sawsharks. Longnose sawsharks often serve as hosts for tetraphyllidean tapeworms.

Economic Importance for Humans: Positive

Longnose sawsharks are commercially fished for their high-quality meat.

• Positive Impacts
• food food

Economic Importance for Humans: Negative

Longnose sawsharks have no adverse economic impact on humans.

• Negative Impacts
• injures humans
  • bites or stings

Conservation Status

Effective efforts have been made to protect longnose sawsharks. Commercial fishing of longnose sawsharks has been reduced due to the implementation of a Total Allowable Catch rule. Also, a three mile stretch of Victorian waters have been closed to all shark fishing, which provides some safe habitat for longnose sawsharks.

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Daniel Krcmaric (author), University of Notre Dame, Karen Powers (editor, instructor), Radford University.

References

Compagno, L. 2006. " Pristiophorus cirratus Longnose Sawshark" (On-line). Accessed February 27, 2006 at http://filaman-.ifm-geomar.de/summary/speciessummary.php?id=721 .

Cropp, B. 1964. Shark Hunters . New York: The Macmillan Company.

Fisheries Global Information System, 2006. "Fisheries Global Information System" (On-line). Accessed February 27, 2006 at http://www.fao.org/figis/servelt?Firefservlet .

Hilton-Taylor, C. 2006. "The IUCN Red List of Threatened Species" (On-line). Accessed February 27, 2006 at http://redlist.org/search/details.php?species=39327 .

Martin, A. 2006. "Order Pristiophoriformes: Sawsharks- 8 Species" (On-line). Accessed February 27, 2006 at http://www.elasmo-research.org/education/sharkprofile/pristiophoroformes.htm .

The British Library, 1999. "Southern Australian Shark Fishery Management" (On-line). Accessed February 27, 2006 at www.bl.uk/services/document/edd.html .

Walker, T. 1999. Southern Australian Shark Fishery Management. FAO Fisheries Technical Paper , 378: 48.

Wikipedia, 2006. "Sawshark" (On-line). Accessed March 23, 2006 at http://en.wikipedia.org/wiki/sawshark .