Barracuda 解除

Barracuda: Habitat, Behavior, and Diet

Debbie Hadley is a science educator with 25 years of experience who has written on science topics for over a decade.

The barracuda (Sphyraenidae spp) is sometimes portrayed as an ocean menace, but does it deserve such a reputation? This common fish found in the Atlantic, Pacific, and Indian Oceans as well as the Caribbean and Red seas, has threatening teeth and a habit of approaching swimmers, but it's not the danger you might think.

Fast Facts: Barracuda

1. Scientific Name:Sphyraenidae

2. Common Name: Barracuda

3. Basic Animal Group: Fish

4. Size: 20 inches to 6 feet or more

5. Weight: Up to 110 pounds

6. Lifespan: Varies by species; giant barracudas live up to 14 years

7. Speed: Up to 35 miles per hour

8. Diet: Carnivore

9. Habitat: Atlantic, Pacific, and Indian Oceans, Caribbean and Red Seas

10. Population: Unknown

11. Conservation Status: Not Evaluated

Description

Even if you're new to fish identification, you'll quickly learn to recognize the barracuda's distinctive look. The fish has a long, slender body that is tapered at the ends and thicker in the middle. The head is somewhat flattened on top and pointed in front, and the lower jaw projects forward menacingly. Its two dorsal fins are far apart, and its pectoral fins are positioned low on the body. Most species are dark on top, with silver sides and a clear lateral line that extends from the head to the tail on each side. The barracuda's caudal fin is slightly forked ​and curved on the trailing edge. Smaller barracuda species may max out at 20 inches in length, but the larger species can achieve a startling 6 feet or longer in size.

Is there anything more unnerving than being approached by a fearless fish with a mouth full of razor-sharp teeth? Barracuda have big mouths, with long jaws and a characteristic under-bite. They also have a lot of teeth. In fact, barracuda have two rows of teeth: an outer row of small but sharp teeth for tearing flesh apart, and an inner row of long, dagger-like teeth to firmly grasp its prey. A few of the barracuda's teeth point backward, as an extra aid for securing squirming fish. Smaller fish are mercifully swallowed whole, but larger fish are efficiently chopped to pieces in the hungry barracuda's jaws. A barracuda can open its mouth wide enough to snatch just about any fish it encounters, from a tiny killifish to a chunky grouper.

Species

The name barracuda doesn't apply to one specific fish, but rather an entire family. The Sphyraenidae is the group of fish known collectively as barracuda. The species most people picture when thinking of a barracuda is probably the great barracuda (Sphyraena barracuda), a commonly encountered fish. But the world's oceans are full of all kinds of barracuda, including the pickhandle barracuda, the sawtooth barracuda, and the sharpfin barracuda. Some species are named for the area where they are found, like the Guinean barracuda, the Mexican barracuda, the Japanese barracuda, and the European barracuda.

Habitat and Range

Most species of barracuda live in near-shore habitats, such as seagrass beds, mangroves, and coral reefs. They're primarily marine fish, although a few varieties can tolerate brackish water at times. Barracuda inhabit the Atlantic, Pacific, and Indian Oceans, and are also commonly found in the Caribbean and Red seas.

Diet

Barracuda have a diverse diet, preferring small tunas, mullets, jacks, grunts, groupers, snappers, killifishes, herrings, and anchovies. They hunt mainly by sight, scanning the water for signs of prey as they swim. Smaller fish are most visible when they reflect light and often look like shiny metal objects in the water. This, unfortunately, can lead to misunderstandings between barracuda and humans in the water.

A swimmer or diver with anything reflective is likely to get an aggressive bump from a curious barracuda. The barracuda isn't interested in you, necessarily. It just wants to sample the object that looks like a shiny, silverfish. Still, it's a bit unsettling to have a barracuda come barreling toward you, teeth first, so it's best to remove anything reflective before getting in the water.

Behavior

A barracuda's body is shaped like a torpedo and made for cutting through the water. This long, lean, and muscular fish is one of the fastest creatures in the sea, capable of swimming up to 35 mph. Barracuda swim almost as fast as the notoriously speedy mako sharks. Barracuda can't maintain top speed for long distances, however. The barracuda is a sprinter, capable of bursts of speed in pursuit of prey. They spend most of their time swimming slow enough to survey for food, and only accelerate when a meal is within reach; they often swim together in small or large schools.

Reproduction and Offspring

The timing and location of barracuda spawning are not as yet well-documented, but scientists surmise that mating takes place in deeper, offshore waters and probably in spring. Eggs are released by the female and fertilized by the male in open waters, and then are dispersed by currents.

Newly hatched barracuda larvae settle in shallow, vegetated estuaries, and leave the estuary when they have achieved a length of about 2 inches. They then stay in mangrove and seagrass habitats until they are about one year old.

Great barracuda have a lifespan of at least 14 years, and they typically reach sexual maturity at two years (male) and four years (female).

Barracudas and Humans

Because barracuda are fairly common and inhabit the same waters where people swim and dive, the chance of encountering a barracuda is quite high. But despite their proximity to people in the water, barracuda rarely attack or injure humans. Most bites occur when the barracuda mistakes a metallic object for a fish and attempts to snatch it. The barracuda isn't likely to continue biting once it realizes the object in question isn't food. Barracuda attacks are rare and almost never fatal. Those teeth will do some damage to an arm or leg, though, so victims usually require stitches.

While smaller barracuda are generally safe to eat, larger barracuda can be ciguatoxic (poisonous to humans) because they consume larger fish with higher toxin loads. At the bottom of the food chain, toxic plankton known as Gambiendiscus toxicus attaches itself to algae on the coral reef. Small, herbivorous fish feed on the algae and consume the toxin, too. Larger, predatory fish prey on the small fish, and accumulate a higher concentration of the toxin in their bodies. Each successive predator accumulates more toxins.

Ciguatera food poisoning is unlikely to kill you, but it's not an experience you'll enjoy. The biotoxins cause gastrointestinal, neurological, and cardiovascular symptoms that persist for weeks or months. Patients report hallucinations, severe muscle and joint pain, skin irritation, and even a reversal of hot and cold sensations. Unfortunately, there's no way to identify a ciguatoxin barracuda, and neither heat nor freezing can kill the fat-soluble toxins in a contaminated fish. It's best to avoid consuming large barracuda.

Sources

1. 'Family Sphyraenidae – Barracuda.' Fishbase.org, 2012.

2. Martin, R. Aidan. 'Record-Breakers: Hauling Bass.' Biology of Sharks and Rays. ReefQuest Center for Shark Research, 2003.

3. Bester, Cathleen. 'Sphyraena barracuda: Great Barracuda.' Florida Museum, University of Florida.

4. Lawley, Richard. 'Ciguatoxins.' Food Safety Watch, January 30, 2013.

5. Olander, Doug. 'The Perils of Ciguatera: Will your next fresh-caught fish dinner be a toxic time bomb?' Sport Fishing Magazine, May 5, 2011.

Barracuda 解除

Barracuda Central maintains a history of IP addresses for both known spammers as well as senders with good email practices. This information contributes to the Barracuda Reputation System, which gives the Barracuda Spam & Virus Firewall the ability to block or allow a message based on the sender's IP address. In addition to IP reputation, the Barracuda Central team maintains reputation on URLs, which gives the Barracuda Spam & Virus Firewall the ability to quickly block an email based on a poorly-rated URL contained in the message. By combining both the IP and reputation data, Barracuda Networks can easily determine whether a message is spam or legitimate email. Once identified, Barracuda Central can implement countermeasures to mitigate these threats.

Barracuda Reputation is one of the many techniques Barracuda Networks employs within the Barracuda Spam & Virus Firewall to reinforce its superior 95 percent spam accuracy rate.

The Barracuda Reputation System is a real-time database of IP addresses that have a 'poor' reputation for sending valid emails. Barracuda Central maintains and manually verifies all IP addresses marked as 'poor' on the Barracuda Reputation System.

Many Barracuda Spam & Virus Firewalls are configured, as a policy, to automatically deliver email that comes from sources that are properly registered at EmailReg.org.

Barracudas

Description Barracudas are muscular fish with streamlined, torpedo-shaped bodies. They are equipped with an impressive set of razor-sharp teeth. The lower jaw juts out past the upper jaw and both are filled with dozens of teeth. Size Many members of this family are small and harmless to humans. The northern barracuda (Sphyraena borealis), for example, lives along the U.S. Atlantic coast from Cape Cod to Florida and only grows to roughly 46 cm (18 in.) in length. The largest species, the great barracuda (Sphyraena barracuda), can grow up to 3 m (10 ft) in length. Female: In general, females grow to be larger than males. Diet Smaller fish Incubation Oviparous (egg laying); spawn in schools Range The great barracuda is found in all temperate and tropical waters except the eastern Pacific Ocean and the Mediterranean Sea Population Global: No data Status IUCN: Not listed CITES: Not listed USFWS: Not listed

Fun Facts

1. Some of the teeth of the great barracuda point backwards to prevent slippery fish from escaping once they are seized.

2. Barracudas hunt more by sight than smell; a fact that may lead to unfortunate attacks on human divers. Barracudas are attracted to shiny objects, like the silvery fish they prey on. Humans that enter the water with glittering objects, such as watches and jewelry, may cause curious barracudas to investigate and mistake these objects for a food source. The number of attacks on humans is probably overstated, but divers that enter the water where barracuda are present should remove shiny objects as a precaution.

3. Interestingly, ingesting barracuda is considerably more harmful to humans than eating any other fish species. People often become ill from ciguatera fish poisoning after ingesting barracudas, perhaps because the reef fish that barracudas eat themselves consume algae that may contain high levels of the toxin.

4. For more information about bony fishes, explore the Bony Fishes InfoBook.

Ecology and Conservation

Many species of barracuda are classified as game fish and are considered of minor commercial importance.

Bibliography

Andrews, A., Parham, D. and W. Street. Bony Fishes. SeaWorld Education Department Publication. San Diego, SeaWorld, Inc. 1995.

Burgess, W. and H.R. Axelrod. Pacific Marine Fishes. Book 4. Neptune City, NJ. T.F.H. Publications, Inc. Ltd. 1974.

Eschmeyer, W.N., Herald, E.S. and H. Hammann. Peterson Field Guide to Pacific Coast Fishes. New York. Houghton Mifflin Co. 1983.