Analysis: About the habitat of sawsharks. Behavior and eating habits
The sawshark, also spelled sawshark, is a shark named for its flat toothed snout that resembles a saw blade. The sawshark is a member of the order Sawshark.
Quick Fact: Saw shark
Scientific name: Sawsharks
Common name: saw shark, saw shark
Basic animal group: fish
Size: 28-54 inches
Weight: 18.7 lbs (common sawshark)
Lifespan: 9-15 years
Diet: Carnivores
Habitat: Deep continental shelf of temperate, subtropical and tropical oceans
Population: Unknown
Protection status: insufficient to near threat
species
There are two genera and at least eight species of sawsharks:
Pliotrema warreni (sixgill sawshark)
Pristiophorus cirratus (proboscis saw shark or common saw shark)
Pristiophorus delicatus (tropical sawshark)
Pristiophorus japonicus (Japanese sawshark)
Pristiophorus lanae
Pristiophorus nancyae (African dwarf sawshark)
Pristiophorus nudipinnis (short-nosed sawshark or southern sawshark)
Pristiophorus schroeder (Bahamian sawshark)
description
The saw shark is similar to other sharks, except that it has a long snout (snout) with sharp teeth on the edges. It has two dorsal fins without fins and a pair of long whiskers near the midpoint of the snout.
The body is usually yellowish brown with spots that allow the fish to camouflage on the seabed. Size depends on the species, but females are usually slightly larger than males. Saw sharks range in length from 28 inches to 54 inches and can weigh up to 18.7 pounds.
Sawsharks vs. sawfish
Both sawsharks and sawfish are cartilaginous fish with blade-like snouts. However, the sawtooth fish is actually a type of ray, not a shark. Sawsharks have gill slits on both sides, while sawfish also have gill slits on the underside.
Saw sharks have tentacles and teeth of alternating sizes, while sawfish teeth are uniform in size and have no tentacles. Both animals use electroreceptors to detect prey through an electric field.
Habitat and range
Sawsharks live in the deep waters of temperate, subtropical and tropical ocean continental shelves. They are most commonly found along the Indian and Pacific coasts. It is found in a wide area from South Africa to Japan.
The Bahamian sawshark was discovered in 1960 at depths of 640 to 915 meters in the Caribbean Sea and was a new species.
Most species live at depths between 40 and 100 meters, but the Bahamas sawshark is found between 640 and 914 meters. Some species migrate up or down in the water column in response to seasonal temperature fluctuations.
Diet and behavior
Like other sharks, sawtooth sharks are carnivores of crustaceans, squid, and small fish. Their tentacles and saws contain sensory organs called Lorenzini's ampulla that detect the electric field emitted by their prey.
The shark weakens its prey and fends off threats by sweeping its serrations left and right. Some species are solitary hunters, while others live in groups.
Reproduction and offspring
Saw sharks mate seasonally, but females only give birth every two years. After a 12-month gestation period, females give birth to a litter of 3 to 22 pup. The pups are born with their teeth close to the nose to protect the mother from harm.
Adults care for young people for 2 years. At this time, the offspring are sexually mature and can hunt on their own. The average lifespan of a sawshark is 9 to 15 years.
Protection status
There are no estimates of population size or trends for sawshark species. The International Union for Conservation of Nature (IUCN) classifies the status of sawsharks based on the likelihood that each species or its prey is at risk of overfishing or bycatch.
The sixgill saw shark is classified as "near threatened". Common sawsharks, southern sawsharks, and tropical sawsharks are classified as "least concerned." There are insufficient data to assess the conservation status of other species.
Under the Convention on International Trade in Endangered Species of Wild Fauna and Flora, sawsharks are listed on the Grade I Protected List and trade is strictly prohibited.
Saw sharks and humans
Due to the depth of their lives, sawsharks do not pose a threat to humans. Some species, such as the long-snouted sawshark, are intentionally fished for food. Others may be caught by gill nets and trawlers and discarded as by-catch.
Bibliography:
Sharks and rays in Australia (2nd edition). CSIRO Press, Collingwood. 2009.
2016 IUCN Red List of Threatened Species
Nature Company Guide: Sharks and Rays. Sydney: Times Life Books. 1997. ISBN 0-7835-4940-7.
