Pristis pectinata

Geographic Range

Smalltooth sawfish ( Pristis pectinata ) have a historic range that includes the Atlantic Ocean, the Gulf of Mexico, and the Indian Ocean. However, smalltooth sawfish populations have dwindled in size in recent decades. Presently, they are found predominantly in the Atlantic Ocean, close to the coast of Florida.

• Biogeographic Regions
• indian ocean
• atlantic ocean atlantic ocean

Habitat

Smalltooth sawfish live in coastal waters, typically at depths of less than 10 m, although they have been reported at depths greater than 70 m. They prefer shallow areas because they are often associated with warmer water temperature. The most suitable water temperature for smalltooth sawfish is estimated to be around 36 °C. They also raise their young in shallow water to avoid large predators, such as sharks, that live in deeper water.

Smalltooth sawfish can tolerate freshwater and saltwater environments, making use of oceans, estuaries, and rivers. Despite their ability to live in freshwater, smalltooth sawfish prefer habitats with salinity levels between 21.4 and 34.7 ppt and dissolved oxygen levels between 3.18 and 8.14 mg/L.

• Habitat Regions
• saltwater or marine saltwater or marine
• freshwater freshwater

• Aquatic Biomes
• rivers and streams
• coastal coastal

• Other Habitat Features
• estuarine estuarine

Physical Description

Smalltooth sawfish adults are 4 to 5 m long (400 – 500 cm) and weigh around 315 kg, on average. Their rostrums constitute around one quarter of their total length. Smalltooth sawfish are about 85 cm at birth and have a high growth rate during their first year of life. Smalltooth sawfish are grey with a brown tinge on their dorsal sides and white ventral sides. They have around 23 teeth protruding horizontally from each side of their rostrums. There is no apparent sexual dimorphism in smalltooth sawfish, except that males have a pair of external reproductive organs, called claspers.

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

• Sexual Dimorphism
• sexes alike

Development

Smalltooth sawfish are ovoviviparous. Neonatal smalltooth sawfish have developed rostrums, but they are more flexible and lack the row of teeth on each side. Smalltooth sawfish are an average of 85 cm long upon hatching. Juvenile smalltooth sawfish inhabit water less than 1 m deep for around 2 years, until they are fully developed and better able to defend themselves. Juveniles grow quickly, at a rate of about 19.6 cm per year. Their growth rate slows significantly by the time they reach maturity, at 400 to 500 cm long.

Reproduction

Smalltooth sawfish have multiple partners in a breeding season. Males reproduce annually, but females have a biennial breeding cycle. Offspring are usually born in spring, between March and April.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

There is limited information regarding smalltooth sawfish reproduction. Females reproduce every other year and give birth to 15 live young, after a gestation period of around 5 months. Males reach sexual maturity when they are around 270 cm long, whereas females reach maturity when they are about 360 cm long. The age at which males and females reach maturity is undetermined.

• Key Reproductive Features
• iteroparous iteroparous
• year-round breeding year-round breeding
• sexual sexual
• fertilization fertilization
  • internal internal
• ovoviviparous ovoviviparous

There is limited information regarding parental investment in smalltooth sawfish.

Lifespan/Longevity

There is limited information regarding lifespans of smalltooth sawfish in the wild. They can live to be 30 to 60 years old in captivity

Behavior

Smalltooth sawfish juveniles inhabit shallow waters, around 1 m deep, where they are safe from large predators and can find small prey to eat. Adults usually move into deeper water when they reach maturity. Little is known about migration patterns of smalltooth sawfish, but water salinity likely plays a role in their movements.

• Key Behaviors
• natatorial natatorial
• motile motile

Home Range

There is limited information regarding quantitative home range or territory sizes of smalltooth sawfish. Smalltooth sawfish spend the majority of their first two years in shallow waters or amongst mangroves. As they mature, they no longer rely on the protection of shallow water and move to areas with a wider range of depths.

Communication and Perception

Smalltooth sawfish perceive their environment through visual, acoustic, and olfactory cues. In clear waters, they rely on their eyesight to catch prey and evade predators. In murky waters, they rely more heavily on their sense of smell and their mechanosensory system to detect vibrations propagating through water. The main mechanosensory system of smalltooth sawfish is the peripheral sensory system, which sends signals to the nervous system and alerts smalltooth sawfish of their immediate surroundings. They also have a lateral line system along each side of their bodies, which is sensitive to vibrations. Smalltooth sawfish can determine the proximity and direction of potential predators and prey by the intensity of the vibrations they detect. Smalltooth sawfish also have organs called ampullae of Lorenzini, which detect electric fields emitted by other organisms in the water.

• Communication Channels
• visual visual
• acoustic acoustic

• Other Communication Modes
• vibrations vibrations

• Perception Channels
• visual visual
• acoustic acoustic
• vibrations vibrations
• chemical chemical
• electric electric

Food Habits

Smalltooth sawfish use the teeth that protrude horizontally from their rostrums as a means of catching prey. When they detect prey ahead, they rapidly move their rostrums side to side to potentially harm or kill their target. Smalltooth sawfish diets consist mostly of mullets (family Mugilidae ), clupeids (family Clupeidae ), and various crustaceans.

• Primary Diet
• carnivore carnivore
  • piscivore piscivore

• Animal Foods
• fish
• other marine invertebrates

Predation

The primary predators of smalltooth sawfish are humans ( Homo sapiens ). Their rostrums easily get tangled in fishnets, which can kill them and damage fishing equipment. Fishermen typically kill smalltooth sawfish when they catch them. Natural predators include several shark species. Smalltooth sawfish have dark, sandy coloration on their dorsal sides, which helps them camouflage with the substrate around them. They also exhibit a type of cryptic camouflage called countershading. Their dorsal sides are grey-brown and their ventral sides are white, which makes them difficult to detect both from above and from below.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

There is limited information regarding the roles that smalltooth sawfish play in their environments. They are predators of small fish and crustaceans and also serve as prey for larger predators, such as sharks. Smalltooth sawfish also serve as host for microbothriid ectoparasites such as Neoheterocotyle ruggierii . These parasites negatively affect smalltooth sawfish health and can increase mortality rates.

Economic Importance for Humans: Positive

Smalltooth sawfish are high in demand at certain fish markets for body parts such as organs, rostral teeth, skin, and fins. Their organs are known to provide a source of vitamin A and their teeth are used in cock fighting as an extra weapon attached to the feet of roosters. Smalltooth sawfish skin is used to make tough leather material for boots or belts and their fins are traded for food. However, their rostrums are highest in demand, with prices of around $5,200 per m of rostrum length.

• Positive Impacts
• food food
• body parts are source of valuable material

Economic Importance for Humans: Negative

Smalltooth sawfish negatively impact fishing practices. They are a common bycatch species in certain areas, and the teeth on their rostrums can damage nets and maim or kill market fish species in the same net. The loss of nets and products reduces the amount of profit fishermen bring in.

Conservation Status

Smalltooth sawfish are listed as endangered under the Endangered Species Act and are considered critically endangered in some areas of the Atlantic Ocean. Smalltooth sawfish have a low reproduction rate and are slow to mature, making them susceptible to further endangerment and extinction. Populations are in decline primarily because their shoreline habitats are increasingly affected by humans. Divers, boats, pollution, and fishing practices all negatively affect smalltooth sawfish. They get caught in fishing nets and are usually killed when brought on board.

Current conservation efforts for smalltooth sawfish are focused on increasing population sizes. Methods of accomplishing this include protecting habitat and limiting the amount of sawfish caught in nets. Also, if fishermen accidentally catch smalltooth sawfish, they are required to return them to the water instead of killing them. By restoring suitable nursery habitats (e.g., mangroves near shorelines), there is hope that smalltooth sawfish will return to locations from which they are extirpated. Researchers are also implementing captive breeding programs and setting aside restricted wild areas in order to conserve smalltooth sawfish populations.

Additional Links

Encyclopedia of Life

Contributors

Shannon Nasca (author), Radford University, Karen Powers (editor), Radford University, Galen Burrell (editor), Special Projects.

References

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Cheung, P., R. Nigrelli. 1983. Dermophthirioides pristidis n. gen., n. sp. (Microbothriidae) from the skin and Neoheterocotyle ruggierii n. sp. (Monocotylidae) from the gills of the smalltooth sawfish, Pristis pectinata. Transactions of the American Microscopical Society , 102/4: 366-370.

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