Sawfish

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Sawfish

While sawfish are often confused with sawsharks, there is one easy way of spotting the difference. While both are cartilaginous elasmobranches, the sawshark is a true shark with gills on its side, while the sawfish is actually a ray and its gills are found underneath. The rostrum - snout - of both species has a saw-like appearance, which leads directly to their descriptive names, although the sawfish's rostrum has a much more even and balanced appearance. Due to the fact that sawfish are nocturnal and rarely visit the surface, there is still little known about most of their existence.


Content List

1. Scientific & Common Names

2. Characteristics

a. Breeding

b. Behavior

3. History

4. Present Status

5. References


Scientific & Common Names

Kingdom - Animalia

Phylum - Chordata

Class - Chondrichthyes

Subclass - Elasmobranchii

Superorder - Batoidea

Order - Pristiformes

Family - Pristidae

Genus - Pristis (2 species), Anoxypristis (1 species)

Common Names - Sawfish, Carpenter Shark


Characteristics

There are only a few species of sawfish - Smalltooth, Queensland or Dwarf, Knifetooth, Narrowsnout, and Common Largetooth. They range in size from about 4 ½ feet for the Queensland, to the largetooth at around 23 feet and 1300 pounds. While sawfish have actual teeth in their mouths - found on the underside of their bodies, like their gills - the tooth-like structures found on the rostrum are actually modified scales called dermal denticles. Unlike the teeth of sharks, these dermal denticles are not replaced when lost. Depending on the species, sawfish can be found in marine, brackish, or freshwater environments


Breeding

While many of their ray and shark cousins lay eggs, sawfish are ovoviviparous and give birth to live young after keeping the developing eggs inside them. Little has been studied about their breeding habits, but they are believed to mate every other year and they give birth to between 5-8 young. The gestation for all species is not known, but the largetooth sawfish have a five month gestation period.


Behavior

Sawfish spend much of their life on the bottom of waterways, waiting for prey, which they then slash or stun with their elongated rostrum, armed with both tooth-like scales and elecrosensitivity. While the rostrum looks fearsome, they rarely harm humans unless provoked and the rostrum can actually be a detriment in that in can tangle in human marine debris such as fishing nets.


History

Sawfish fossils can found alongside other ancient species and are often collected and traded. The earliest species appeared in the fossil records around 100 million years ago and what we consider modern species appeared 56 million years ago.


Present status

All species of sawshark are either endangered or critically endangered and many countries, including the United States (although only the smalltooth species are currently found in US waters), have strict laws for their protection. It has been half a century since the largetooth has been seen in the US.


References

Sharks, Skates, and Rays of the Gulf of Mexico: A Field Guide Paperback by Glenn R. Parsons

No Turning Back: The Life and Death of Animal Species by Richard Ellis

Fossil Shark Teeth of the World by Joe Cōcke

Florida Museum of Natural History Ichthyology - http://www.flmnh.ufl.edu/fish/Gallery/Descript/KTSawfish/KTSawfish.html

NOAA Fisheries Office of Protected Species