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Home › Sea Life › Marine › Vertebrate › Shark Species › Sawshark

Interesting Facts about Saw Sharks

[Phylum: Chordata] [Class: Chondrichthyes] [Subclass: Elasmobranchii] [Order: Pristiophoriformes]

They're often confused with sawfish (Pristidae), which are a type of large ray fish, but sawsharks actually belong to the order Pristiophoriformes.

This section contains information about the 10 recognised sawshark species, including where they are found, what they eat, and how they reproduce.

Global Distribution and Habitat of Sawshark

The geographic range for most Pristiophoriformes is confined to certain temperate and tropical waters, including the Atlantic Ocean.

However, the hotspots for several species of saw sharks are the Indian Ocean and the Pacific Ocean, in particular:

• Southern Australia
• Western Indian Ocean (Madagascar, Mozambique, and South Africa)
• Japan (including Korea and northern China)
• The western Atlantic (The Bahamas and Cuba)

Sawsharks are bottom-dwellers (demersal) with a distinct preference for scavenging around soft sediments, such as muddy or sandy seabeds.

Some species travel in small groups across the ocean floor in the shallow waters of temperate regions. Whereas, others lead somewhat solitary lifestyles in the deep coastal waters of the tropics.

In general, they form habitats on continental shelves and upper slopes in deep water, typically from forty (40) to one thousand (1,000) metres below sea level.

Sawshark Characteristics and Features

Unlike many in the shark phylum, saw sharks are relatively small. But, the standout feature of these deep-living, cartilaginous sharks has to be the snout or bill, a toothed saw-like flattened rostrum with nasal barbels.

Species in the sawshark genus Pliotrema have six (6) pairs of gill slits, and members of the genus Pristiophorus have five (5) pairs.

Here's the thing:

Unlike ray fish and sawfish, the gill slits are located on each side of the flat head (not underneath). They also have two large spiracles behind the eyes that can take in water to assist with respiration - such as while they're resting on the ocean floor.

Members of the sawshark phylum have two (2) dorsal fins, two (2) long sensory barbels located midway along the rostrum (saw), and wide pectoral fins - but they have no anal fins.

They also have thousands of jelly-filled openings (known as ampullary pores) on the upper and lower sides used to detect weak electrical fields given off by their favourite prey (bottom-dwelling crustaceans).

Sawshark Rostrum

The most recognisable structure in sawsharks is the long snout (rostrum) edged with razor sharp transverse teeth-like projections on each side - teeth that usually alternate big and small.

They are equipped with electrosensory organs (ampullae of Lorenzini) that are capable of detecting any prey that may be buried in soft sediments.

Sawshark Size and Colour

The African dwarf sawshark is one of the smallest in the species, rarely reaching more than sixty centimetres long (24 inches).

By comparison, one of the biggest sawsharks is Warren's sixgill sawshark. Fully grown adults can be 1.7 metres in overall body length (5.6 feet).

The colouring of the cylindrical shaped body is usually light brown with a hint of gray on top. Pale "countershading" below also helps to create an effective camouflage on pale brown sandy seabeds.

What Do Sawsharks Eat?

These active hunters use their rostrum as a sensory device and an efficient slashing tool to stun, or cripple, their prey.

Having eating habits that are based on a diet composed of benthic organisms means saw sharks primarily feed on crustaceans, cephalopods, and small bony fishes.

Types of Sawshark

How Do Saw Sharks Reproduce?

Saw sharks reach their reproductive maturity from the age of two (2) and they typically have a gestation period of around 12 months.

Internal fertilisation occurs when a male sawshark uses his modified pelvic fins (called claspers) to transfer sperm into a female.

The eggs develop inside the uterus of the female, but they are not connected by a placenta. Instead, the embryos get their nourishment from the yolk sac.

But wait - there's more:

They give birth live in shallow coastal areas mostly during winter months, often with five (5) to twenty (20) pups per litter.

Juveniles are born with modified placoid scales (rostral teeth), which are soft and folded back at birth to reduce injury to the mother.

Newborn sawsharks look like miniature versions of adults when they are born. They are already equipped with the distinctive sawshark rostrum.

Sawshark Predators and Threats

Many sawshark species have small populations that tend to be localised in distinct areas. As a consequence of that, they face a combination of natural predators and human-related threats.

In the wild, sawsharks are prey for a number of large predatory sharks, such as bull sharks (Carcharhinus leucas) and tiger sharks (Galeocerdo cuvier).

Although less common, small saw sharks are also taken by large marine mammals, especially dolphins and orcas.

In some regions, humans use targeted fishing practices to catch sawsharks for their meat, fins, and liver oil. Other notable human-related threats include habitat degradation, ocean pollution, and bycatch in fisheries.

Important: An assessment from the IUCN Red List of Threatened Species in June 2019 shows the conservation status of most sawsharks worldwide is of "Least Concern" (LC) with some being classed as "Data Deficient" (DD).

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