Sawfish, also known as carpenter sharks, are of the rays family and characterized by a long, narrow, flattened rostrum, or nose extension, lined with sharp transverse teeth, arranged to resemble a saw.
5 Interesting Facts About Sawfish
#1 Sawfish do not have normal bones
- The sawfish skeleton is made of cartilage.
#2 Rows of Teeth are Modified Scales
- The sawfish’s most distinctive feature is the saw-like rostrum, covered with electrosensitive pores that allow the sawfish to detect slight movements of prey hiding in the muddy seafloor. The rostrum also serves as a digging tool to unearth buried crustaceans. Should suitable prey try to swim past it, the usually lethargic sawfish springs from the bottom and slashes at it with its saw, which generally stuns or impales the prey sufficiently for the sawfish to devour it. Sawfish also defends themselves with their rostrum against intruding divers and predators such as sharks. The “teeth” protruding from the rostrum are not real teeth, but modified tooth-like structures called denticles.
#3 Grow up to 20 feet long, known to grow over 25 feet
- The smallest sawfish is the dwarf sawfish (P. clavata), which grows to 1.4 m (4.6 ft), much smaller than the others. The largest species seem to be the large-tooth sawfish (P. microdon), the Leichhardt’s sawfish (P. perotteti), and the common sawfish (P. pristis), which can all reach about 7 m (23 ft) in length.
#4 Sawfish are ovoviviparous
- Instead of laying eggs, the eggs stay inside of the body, hatch inside, and are born live. The live pups are born with rostral blades that are soft and flexible during embryonic development, with teeth that are enclosed by a sheath – to protect the mother during the birthing process – which eventually disintegrates and falls off.
#5 Population declining, 95% wiped out
- Sawfish is listed as Endangered or Critically Endangered by the IUCN, and face the threat of extinction as a result of habitat loss and overfishing. Global populations of every species of sawfish are estimated to have fallen to less than 10% of their historic levels. International commerce of sawfishes has been banned globally since 2007, with the only exception being for the provision of live Pristis microdon to appropriate public aquaria for primarily conservation purposes.
More Weird Things About Sawfish
- The body and head of the sawfish are flat, and they spend most of their time lying on the seafloor. The sawfish’s mouth and nostrils are on its flat underside. The mouth is lined with small, dome-shaped teeth for eating small fish and crustaceans. Sawfish breathe with two spiracles just behind the eyes that draw water to the gills.
- The eyes of the sawfish are underdeveloped due to their muddy habitats. The rostrum is the primary sensory device.
- Their small intestines contain an internal partition shaped like a corkscrew, called a spiral valve, which increases the surface area available for food absorption.
- One southern sawfish was recorded as weighing 2,455 kg (5,412 lb). Such massive specimens that survive long enough to approach their maximum size and age are believed to have lifespans of about 51 years.
Distribution and habitat
- Sawfishes are marine and move between freshwater and saltwater, brackish water.
- Species and are widely distributed in the Atlantic and Indo-Pacific.
- Juveniles are common in very shallow waters, but adults can be found at depths of 40 m (130 ft) or more.
- Sawfishes are nocturnal, usually sleeping during the day and hunting at night.
- They do not attack people unless provoked or surprised.
- The sawfish is known to mate once every two years, with an average litter of around eight.
- It is estimated that the larger species do not reach sexual maturity until they are 3.5 to 4 m (11 to 13 ft) long and 10 to 12 years old.
Featured Image Credit: Rob Griffith / AP