Latest Issue of Science News

Wild Things

The weird and wonderful in the natural world
Sarah Zielinski

Wild Things

Wild Things

Secrets of a sailfish attack

The large, long-nosed fish use their rostrums more like a sword than a spear

Sailfish are named for the sail-like fin on their backs, but they can also be characterized by their elongated bills.

Sponsor Message

Many of us are familiar with sailfish — relatives of marlin— only from seeing them on the walls of sport fishermen. But watching them underwater, whether in person or on video, shows how beautiful the animals are in their natural habitat (see video below).

These fish hunt in groups, driving schools of smaller fish, such as sardines, toward the surface. Then each sailfish takes a stab at the prey. Just what’s going on can be hard to see, so Paolo Domenici of the Istituto per l’Ambiente Marino Costiero in Torregrande, Italy, and colleagues slowed down the action.

The researchers located sailfish off the coast of Cancun, Mexico, in February 2012 by following frigate birds, pelicans and other birds flying above sardine schools. Then they created high-speed videos of the sailfish as they hunted the sardines. The videos gave the researchers a detailed look at what was going on underwater. Their study was published April 22 in the Proceedings of the Royal Society B.

Sailfish are fast swimmers, but they’re not relying on speed to catch their meals, the researchers found. Instead, a sailfish stealthily inserts its long nose (also called its rostrum or bill) into the school. The sardines don’t take notice, and they’re unprepared for what happens next: The sailfish either makes a slashing motion with its rostrum, injuring several sardines, or it taps a single sardine, destabilizing it. The sailfish’s rostrum may look like a pointy spear, but the fish never actually uses their weapon in that way.

The sardines are unable to do anything in response to the sailfish’s attack. And though sardines are fast swimmers, they can’t swim fast enough to avoid the tip of the sailfish’s rostrum, which has “one of the highest accelerations ever recorded in an aquatic vertebrate,” the researchers note.

“Based solely on speed, large fish are expected to eventually catch small fish, but when maneuverability and acceleration are taken into account, large fish are often at a disadvantage,” the researchers write. “Therefore, the use of morphological adaptations that can be maneuvered effectively, such as the sailfish bill, can be critical for overcoming these challenges thereby allowing large predators to catch their evasive smaller prey.”

Most sailfish attacks didn’t result in dead sardines. Only 10 percent of slashes and 33 percent of taps resulted in a direct capture of a sardine. And slashing never resulted in immediate death. But as different sailfish attack a school, more and more sardines are hurt. This type of hunting is surprising because it’s more typical of animals that hunt in packs, such as wolves. Sailfish hunt in groups, but those groups regularly break up and reform with new members.

The underwater videos also picked up some interesting details in the behavior of a sailfish during an attack: The fish keeps its large dorsal fin and pelvic fins erect, probably to keep its body stable. And its body changes color, with the normally bluish-silver lateral sides darkening to almost black just before beginning an attack. Some of the sailfish also showed vertical stripes and blue and orange spots on their sides when they were attacking a school of sardines.

It’s not quite clear what the color changes mean, but they could be some kind of communication between sailfish. The fish attack a school only one at a time — possibly to avoid getting slashed by a compatriot — and they may be using the changes in body color as a way to signal who goes first.

Note: To comment, Science News subscribing members must now establish a separate login relationship with Disqus. Click the Disqus icon below, enter your e-mail and click “forgot password” to reset your password. You may also log into Disqus using Facebook, Twitter or Google.

Conservation,, Animals

Cheetahs, but not wild dogs, manage to live with lions

By Sarah Zielinski 3:14pm, April 21, 2014
One conservation tenet says that cheetahs can’t survive when lions are around, but it’s wild dogs that disappeared in one lion-dense area of the Serengeti.
Animals,, Paleontology

Little thylacine had a big bite

By Sarah Zielinski 2:00pm, April 20, 2014
A reconstruction of the skull of a thylacine, an extinct, fox-sized Australian marsupial, reveals that the animal could have eaten prey much larger than itself.

How a chimp goes mattress hunting

By Sarah Zielinski 4:49pm, April 17, 2014
Chimpanzees prefer firm beds made of ironwood, a new study finds.
Oceans,, Animals,, Ecology

The surprising life of a piece of sunken wood

By Sarah Zielinski 3:45pm, April 14, 2014
Timber and trees that wash out to sea and sink to the bottom of the ocean hold a diverse community of organisms.
Animals,, Conservation

Lionfish grow wary after culling

By Sarah Zielinski 11:30am, April 11, 2014
Efforts to control invasive lionfish could make them more difficult to catch.

Small sperm whale species share a diet

By Sarah Zielinski 12:30pm, April 9, 2014
Dwarf and pygmy species of sperm whales overlap in what they eat, and that could be a problem as the food web changes around them.

Young vervet monkeys look to mom when learning

By Sarah Zielinski 10:01am, April 4, 2014
Among vervet monkeys (Chlorocebus aethiops), behaviors are passed from mother to child, a new study finds.

Pandas enjoy the sweet life

By Sarah Zielinski 5:41pm, April 2, 2014
Unlike many of their carnivore relatives, bamboo-loving pandas can taste natural, and some artificial, sugars.
Animals,, Climate

As their homes warm, salamanders shrink

By Sarah Zielinski 9:00am, March 29, 2014
Many species of salamanders respond to climate change by getting smaller.

Skewed gender ratios turn bird world into a soap opera

By Sarah Zielinski 12:24pm, March 26, 2014
Infidelity, divorce and polygamy become more common among birds when one sex is rarer and has more choice in partners.
Subscribe to RSS - Wild Things