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 ; tactile ; chemical ; electric
Perception Channels: visual ; tactile ; chemical ; electric
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.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
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.
Longnose sawsharks have no adverse economic impact on humans.
Negative Impacts: injures humans (bites or stings)
Longnose sawsharks are commercially fished for their high-quality meat.
Positive Impacts: food
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.
Commensal/Parasitic Species:
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.
Animal Foods: fish; mollusks; aquatic crustaceans
Primary Diet: carnivore (Piscivore , Eats non-insect arthropods, Molluscivore )
Pliotrema warreni 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 ); pacific ocean (Native )
Longnose sawsharks prefer a variety of marine habitats including the open sea and coastal regions. They are typically found at depths below 40 meters.
Range depth: 40 to 310 m.
Habitat Regions: tropical ; saltwater or marine
Aquatic Biomes: pelagic ; benthic ; coastal
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.
Range lifespan
Status: wild: 15 (high) years.
Pliotrema warreni 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.
Range mass: 18.7 lbs or 8.5 (high) kg.
Range length: 4.9 ft or 1.49 (high) m.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: female larger
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.
Known Predators:
Anti-predator Adaptations: cryptic
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.
Breeding interval: Individual longnose sawsharks breed biennially (in alternating years).
Breeding season: Longnose sawsharks have a yearly breeding/spawning season.
Range number of offspring: 3 to 22.
Average number of offspring: 10.
Average gestation period: 12 months.
Range time to independence: 1 to 2 years.
Average age at sexual or reproductive maturity (female): 2 years.
Average age at sexual or reproductive maturity (male): 2 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); 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)
