Billfish: The Contenders for Fastest Ocean Swimmer
Billfish, a group of marine predators with elongated upper jaws and pointed snouts, are widely regarded as the fastest swimmers in the ocean. The speediest of these is the sailfish (Istiophorus). However, the bluefin tuna poses a serious challenge to their dominance, according to IFL Science.
Sailfish: Adapted for Breakneck Speed
Sailfish are well-adapted for blazing speeds in pursuit of prey. Reaching up to 10 feet in length from head to tail, they belong to the Istiophoridae family and are characterized by an exceptionally large dorsal fin that resembles the sail of a ship. Two species fall under the Istiophorus genus: the Atlantic sailfish (I. albicans) and the Indo-Pacific sailfish (I. platypterus).
Atlantic Sailfish: Blazing Fast Sprints
The Atlantic sailfish (Istiophorus albicans), also known as Istiophorus americanus, is a marine sailfish species in the Istiophoridae family. Measuring up to 5.6 feet and weighing up to 44 pounds, it exhibits bursts of speed up to 69 mph.
Prehistoric Appearance and Lightning-Fast Reactions
Sailfish have a prehistoric appearance, with a fearsome demeanor. The Atlantic sailfish (Istiophorus albicans), especially, evokes the image of a sailboat racer. Its large dorsal fin extends along the length of its body and unfurls to resemble a sail. This massive structure assists in sudden stops and turns during high-speed swims. Its sail can reach twice the height of the body.
Speed and Feeding Strategy
The Atlantic sailfish has a metallic-blue body with a sail dorsal fin, a long, pointed bill. Tests conducted in the 1920s estimated that they could reach speeds of up to 69 mph in short bursts. They hunt below the ocean surface or at mid-depths.
Habitat and Behavior
Atlantic sailfish inhabit the Atlantic Ocean, ranging into temperate latitudes. They are found in the Atlantic and Caribbean except for in large areas of the central North Atlantic and South Atlantic, between the surface and depths of 650 feet.
Sailfish typically lead solitary lives and roam tropical and subtropical waters. They spend most of their time swimming near the surface. Although primarily solitary swimmers, they occasionally swim in small groups.
Cooperative Hunting Tactics
With their astonishing speed, sailfish are capable of catching up to their prey, such as tuna, herring, sardines, and mackerel. They use their long bills to skewer their victims. When a fish is incapacitated or killed by this deadly blow, the sailfish quickly turns around and consumes its catch. On occasion, they may rush through a school of fish with such speed and force that they unintentionally propel themselves out of the water.
Conservation and Reproduction
Sailfish are opportunistic feeders, consuming a wide variety of marine animals, including most fish and squid they encounter.
Female sailfish lay eggs in the open ocean, and males release sperm into the water, where fertilization takes place. Eggs drift with ocean currents. They hatch relatively quickly, with fertilized eggs developing into juveniles within 1.5 days. A single female may produce between 4 and 5 million eggs during a breeding event, but most of these do not survive to adulthood. However, juvenile sailfish grow rapidly, reaching lengths of 4 feet within a year. They have an average lifespan of about 10 years.
Speed Claims Debunked
While sailfish rank among the fastest marine animals, recent research suggests they may not be as swift as once believed. In the 1940s, scientists estimated sailfish could reach speeds of nearly 98 mph. However, a 2015 study indicated this velocity was likely exaggerated. The authors calculated that sailfish could not swim faster than 33 ft/s, or 22 mph.
Bluefin Tuna: A Challenge to Sailfish Supremacy
It is possible that sailfish cannot maintain their top speeds for extended periods. They likely reach these bursts of speed for brief durations while pursuing prey. Much of the time, this large predator cruises at speeds comparable to a human walker.
A 2015 project by the Central American Billfish Association recorded an Indo-Pacific sailfish (I. platypterus) accelerating at 1.79 G, according to the University of Massachusetts Amherst Large Pelagics Research Center. If the fish maintained that acceleration for just two seconds, it would reach an approximate speed of 78 mph.
However, bluefin tuna may pose a challenge to the sailfish's top spot. The Large Pelagics Research Center conducted similar studies on bluefin tuna and found they could accelerate at 3.27 G, more than 1.8 times the recorded acceleration of sailfish. Yet, these are merely acceleration bursts, and it is unclear how long the fish can sustain such efforts.
Land Speed Records for Comparison
Speed records become more definitive on land. The accolade for terrestrial speed belongs to the cheetah, a type of big cat native to Africa. The cheetah's commonly cited top speed is 75 mph, although that record was set decades ago and is likely out of date. In 2012, a cheetah named Sarah achieved a top speed of 61 mph at the Cincinnati Zoo, setting the current world record.