Q. I was with friends in a restaurant that had a stuffed swordfish on the wall. Someone said they are the fastest fish in the world. Someone also mentioned a sawfish, which I had never heard of. Are there different kinds of swordfish, are they really that fast and is there such a thing as a sawfish?

A. Several species of large, fast-swimming marine fish have elongated snouts that resemble swords. One species found worldwide from tropical and subtropical seas to both north and south temperate regions in all major oceans is generally referred to as a swordfish.

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Others, such as sailfish, Atlantic blue marlin and black marlin, are related species of bony fishes that also have extended snouts resembling swords. Some fish, such as pickerel and needlefish, have long snouts, but these are extensions of the jaws and have teeth. The mouth of a swordfish is below and at the base of the rapier-like snout.

Sawfish are a completely different group of fish more closely related to rays and sharks than to the various swordfish. They have no bones, only cartilaginous skeletons. But whether shaped like a sword or a saw, that extension is a formidable weapon that stuns or kills prey when slashed through a school of fish.

The use of the sword as a piercing weapon against potential predators has been proposed. I know of no documented observation of a fish using its sword in defense. I do know someone who encountered the business end of a small sawfish that slung its snout around and hit his leg. Getting smacked by an adult’s enormous sawblade would presumably deter even a shark. The use of these armaments to capture prey has been documented. It’s plausible, even likely, they also use them for defense.

As for size, most of these fish are in the top of their class; all reach lengths over 10 feet from sword tip to tail tip. Black marlin of the Pacific Ocean have been recorded at lengths over 15 feet.

According to the National Oceanic and Atmospheric Administration, juvenile smalltooth sawfish of Florida’s coastal waters are more than 10 feet long and adults can reach a length of 16 feet. Largetooth sawfish have been reported to be more than 20 feet long.

According to the Australian Museum, the Indo-Pacific sailfish has been billed as the fastest fish on earth and “clocked at more than 68 mph over short periods.” Alas, a paper published by S. Marras, T. Noda and colleagues in the scientific journal Integrative and Comparative Biology took the wind out of those sails with an experiment using high-speed video. The investigators recorded sailfish maximum speeds at only a bit over 20 mph, which nonetheless is really fast for a fish.

More sailfin tests under different conditions could possibly document faster swimming speeds and edge the documented sailfin record closer to the higher number. For now, assuming the latest experiment is close to the maximum, sailfish speed is slower than Usain Bolt’s 27-mph land record and a lot slower than an African cheetah’s 75 mph.

Of course, none of these land and sea records can hold a feather to the speed of a diving peregrine falcon — 240 mph.

All swordfish are prize game fish. Sadly, declining population sizes in most oceanic regions have led to some being considered endangered species.

Sawfish are in an even more perilous situation. The Florida Museum of Natural History states, “The decline in sawfish populations worldwide has prompted the International Union for Conservation of Nature (IUCN) to list” all species of sawfish as endangered.

According to the National Wildlife Federation, the smalltooth and largetooth sawfish are the two species native to Gulf coastal waters. IUCN lists both as critically endangered.

These remarkable weaponized creatures should make us reflect on the impact of sports and commercial fishing that targets any of the swordfish. And how the degradation of coastal habitats adversely affects the amazing sawfish.

Whit Gibbons is professor of zoology and senior biologist at the University of Georgia’s Savannah River Ecology Laboratory. If you have an environmental question or comment, email ecoviews@gmail.com.

This article originally appeared on The Tuscaloosa News: What is the difference between a swordfish and a sawfish? | ECOVIEWS