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Introduction
The great barracuda, Sphyreana barracuda, has earned a nasty reputation in the public eye, and much of this has to do with negative media exposure it receives all around the world. Many people have wildly inaccurate ideas about barracudas and believe all different types of myths about the fish. Even the other day, when talking to a friend about this paper, he said Òthose things are poisonous, right?Ó No, barracudas are not poisonous, at least not in the way that he meant (their bite). This is just one misconception that my friend is not alone in having. Barracudas are regarded as a very dangerous fish to swimmers, yet there is much evidence that questions this claim. So is the great barracuda a danger to humans? Are they more of a threat than sharks? These are just two questions that I set out to answer in this paper, and possibly shed some light on this fascinating predator.
Habitat
Barracudas are a warm water fish that are found typically between the latitudes of 30¡N and 30¡S. They are found in the Atlantic, the Pacific, the Caribbean, and nearly all warm seas in this range all around the world. The one place that they are rare or even absent is in the Eastern Pacific ocean, and this interesting point is currently unexplained. They are usually found in shallow waters near mangroves, sea grass, and along coral reefs. They also have been found out in the open ocean, on occasion, ranging from a few feet below the surface to 325 ft. down. Great barracudas tend to avoid brackish waters unless they are getting ready to spawn.
Physical Characteristics
Barracudas are long and slender in shape, much like a torpedo sporting teeth. The top of their head is nearly flat between the eyes, and their large mouth is filled with two rows of flat, razor sharp teeth. The outer row is comprised of the smaller teeth, while the inner row is a set of larger razors, both designed for tearing flesh. The long needle-like teeth found in the barracudaÕs mouth each have a hole on the opposite jaw so that the barracuda can close its mouth, and making it even more difficult for prey to escape.
The body is colored brownish to bluish gray on the upper sides, and fades to greenish to silver on the lower sides, with a white belly. Along the upper sides there are anywhere from 18 to 23 dark bars. The feature that distinguishes the great barracuda from other species of barracuda is that there is a set of black spots along the lower sides. Often, adults develop a more silvery appearance, which is advantageous to fish who hunt in shallow waters.
The body of the great barracuda has a set of two dorsal fins, the spinus and the soft dorsal fins, which are spaced widely apart, and are characteristic to the family Sphyraenidae. Different rates in growth during the juvenile period determine differences in body proportions in adulthood, including the distance between these two dorsal fins.
Their powerful bodies are designed perfectly for traveling very fast and very efficiently. They are believed to be able to reach speed of approximately 36 mph, which is about 53 ft/sec. Great barracudas are known to reach around six feet long and weigh over 100 lbs. The largest great barracuda ever caught by a fishing line was 5 ¸ feet long and weighed 103 lbs, but there have been reports, though not verified, of barracudas that have been seen which are estimated close to 10 feet long. A barracuda that is over 4 ¸ feet long is considered a large barracuda.
Reproduction
Reproduction practices of great barracuda are largely unknown. It is argued about where, when and how often barracudas spawn. It has been found that barracudas display different spawning patterns around the world. They may spawn in the spring, they may spawn with certain phases of the moon, or at any other point in the year excluding the winter months. It is even possible that barracudas may spawn more than once in a given year.
Often barracudas will head to the shallow, protected waters of estuaries in order to spawn, and this is where the new fish begin their life. The larvae are abandoned by the adults and left to drift. The tiny fish take shelter in the estuaries until they reach about 3 inches in length, and then they move to the margins of the estuaries and shallow, weeded areas. At 12 inches the larvae begin to resemble the adults in coloring and shape, and the small barracudas venture into the more open waters around the estuaries, and finally move out of the estuaries completely at 20 inches. Males and females reach sexual maturity at different times. The males will reach maturity soon after they venture out of the estuaries, after 740 days on average (~2 yrs), while the females wonÕt reach maturity until 1,460 days on average (~4 yrs).
Hunting and Behavior
The great barracuda is usually a solitary predator, especially at night. However, they have been known to school during the day, sometimes in the hundreds or even thousands, but this is very rare. Their reasons for schooling are unknown, but it is most likely beneficial in hunting prey and also for protection from predators. Barracudas feed on reef fish such as jacks, grunts, groupers, small tunas, and others. It has a very large gape that can open to 20¡, so it can feed on prey that normally would be too big to kill. Unlike sharks, barracudas are not attracted to the smell of blood in the water. Instead, the prey is located by using acute visual and olfactory senses, and the barracuda utilizes both a sit-and-wait method and an active predator style of hunting. Once prey is found, the barracuda uses a tactic known as ram-biting, where it will swim at high speeds towards its prey. When it hits the target, it is forced to the back of the barracudaÕs large gape and triggers the jaw muscles to slam shut. The muscles responsible for closing the mouth are extremely efficient, turning the jaws into a natural form of scissors. It is common for prey to be cut into half by the raw force of the blow combined with a mouth designed to do as much damage as possible with a single attack. If the prey is not killed on the initial impact, the barracuda performs a series of powerful bites and lateral head shakes to kill the prey. These two features of the attack give it the name Òram-bitingÓ, and very few other fish use this unique ability.
With prey that is too large to swallow whole, the great barracuda will cut it into more manageable sixes. It has been documented that barracudas have been caught with only having the Òback halvesÓ of fish in their stomachs. It is believed that because barracudas are advantageous predators, they sometimes will kill more than they can eat. It has also been found that barracudas will herd a school of fish into shallow waters and guard them until their last meal finishes digesting.
Dangerous to Humans?
Barracudas have a very mysterious quality about them. Since they are so fast in the water, divers often tell of the surrounding waters being empty one moment, and suddenly a barracuda appears the next. Great barracudas are very bold and inquisitive, and they have an unnerving habit of following divers. They will keep a constant distance of a few meters away, and will wait to scavenge any kill that the diver makes. It is because of this that humans have developed a fear of this fish that can grow to be the size of a small person.
Despite the fact that barracudas will scare divers by following them around, attacks on humans are very rare. According to Donald de Silva, there have only been 25 documented and confirmed barracuda attacks in the last century. This is compared to shark attacks, which reported 58 attacks in 2005 alone (and this number had dropped for the fifth year in a row). When a barracuda attacks a human, it is usually a single fast strike that results in a laceration and loss of tissue, but it is very rarely deadly. Often when a barracuda gets hungry enough, it will strike anything that is shiny. This can include a shiny-scaled reef fish, or also a diving knife or watch. This accounts for many of the attacks on divers.
It has to be stated that barracuda attacks may be severely under reported compared to shark attacks, so the numbers from above possibly could be inaccurate. When a shark attacks a person, it usually requires serious hospitalization and draws lots of attention from other people. When a barracuda attacks, it may require stitches, but rarely anything serious. These attacks may not gain the attention that a shark attack might. Also, many barracuda attacks may go unreported in smaller communities of pearl divers, shell divers, and spear fisherman. Many attacks, on spear fisherman especially, are brought about because the fisherman refuses to share their catch with a nearby hungry barracuda.
Barracudas have been known to act strangely on occasion, sometimes acting like they have a vendetta against a diver or fisherman. Several attacks have been reported where the barracuda streaks directly at the diverÕs face, only to veer at the last minute and hit their leg or arm. This can be dangerous if the bite hits any major arteries causing a significant amount of blood loss. Other accounts tell of barracudas jumping into fishing boats and seemingly continue to bite at the occupants. These types of attacks are rare and unexplained, but serve to further our image of these fish as being extremely dangerous. The truth is barracuda attacks can generally be avoided by taking simple safety precautions when in the water with barracudas, and not provoking any aggression from the fish.
Ciguatera Poisoning
The great barracuda is not on the endangered species list, but people should still think twice about fishing for it. The more immediate threat to humans from barracudas is almost completely flipped from what people currently believe. In actuality, barracudas are far more dangerous to humans once they are dead, rather than alive. Along reefs around the world, an invisible killer threatens humans. Ciguatera poisoning is a very serious illness that comes from eating infected reef fish from tropical and subtropical waters. Dinoflagellates (algae) that form on the reefs produce ciguatoxins, and are eaten by herbivorous fish. Those fish, in turn, are eaten by larger reef predators, which again are eaten by larger predators, such as the great barracuda. The ciguatoxin travels up the food chain, gaining concentration with each level. The size of the fish that is infected only relates to the degree of toxicity in regards to a larger fish will have had more opportunity to ingest smaller infected fish. Humans cannot see, taste, or smell the ciguatoxin, and unlike food borne bacteria, it cannot be killed by cooking, drying, freezing, or otherwise processing the fish. It was once believed that flies would not land on meat contaminated with ciguatoxin, and that cats would refuse to eat tainted fish (allegedly being highly sensitive to the ciguatoxin), but the validity of these claims is still in question. Researchers at the University of Hawaii are working on a method to be used by fisherman to detect ciguatera in their catches, but it has not yet been completed. The challenge is that there are many different forms of ciguatera, and the strain can differ even between sections of the same coral reef. Despite this, local fishermen in these areas have developed an in depth knowledge about which spots are free from the ciguatoxin, and surprisingly, they are extremely accurate.
A major contributor to the increase in ciguatera poisoning is the increased level of human activity in these areas. When humans pollute the water, this provides a better opportunity for ciguatoxin producing dinoflagellates to grow, thus increasing the amount of ciguatoxin in the area.
Ciguatera poisoning is often initially mistaken for a Òstomach bugÓ because it begins with many of the same symptoms. Symptoms can begin as soon as 3-6 hours after eating the infected fish. At first, gastrointestinal symptoms set in, including nausea, vomiting, diarrhea, and stomach cramps. After a day or two, these symptoms subside, but only to make way for much more serious neurological symptoms. Patients begin to experience joint and muscle pain, weakness and fatigue, dizziness, numbness in the limbs, and often itchy mouth, hands, or feet. The signature symptom of ciguatera poisoning is the inversion of touch senses; hot things feel cold, and cold things feel hot. Though the GI symptoms subside within a day or two, the neurological symptoms can linger for weeks or even months, and a few cases have even resulted in death. The symptoms can vanish and then reoccur, especially after drinking alcohol, exercising, and having sex. There is no proven antidote for the illness at this point, but one promising experimental treatment called Manitol has shown to be affective, but only if administered 24-48 hours after consuming the ciguatoxin.
Conclusion
The great barracuda is one of the worldÕs most well designed predators; however, their biggest threat to humans comes after we have killed them. ItÕs ironic that the underlying reason for the increase of ciguatera poisoning could be humans themselves. Essentially, we are making barracudas more dangerous to humans by polluting waters and destroying habitats. Besides the threat of ciguatera poisoning, barracudas are relatively passive towards humans. Attacks are rare if unprovoked, and those attacks that occur are usually minor injuries when compared to attacks by other large predators such as sharks. The myths surrounding barracudas strike fear into most people, and even myself until I had further researched this topic, but instead of fearing these animals they deserve respect form us. They are no where near as deadly to humans through attacks as people believe, rarely attacking, and even more rarely killing a human. Understanding is the key for future relations with this species.
References
Bester, Cathleen. "Great Barracuda." Ichthyology. 2008. Florida Museum of Natural History. 1 June 2008 Certain Fish From Tropical Locales Could Harbor a Dangerous Toxin. 2008. Tufts University Health & Nutrition Letter. 1 June 2008 "Exploring the Myth of Crazy 'Cudas... the "Tigers of the Sea"" Dive News. 21 Jan. 2006. 12 May 2008 Fuller, Brianne. "Sphyraena Barracuda." Animal Diversity Web. 1995. University of Michigan Museum of Zoology. 12 May 2008 Grubich, Justin R., Aaron N. Rice, and Mark W. Westneat. "Functional Morphology of Bite Mechanics in the Great Barracuda (Sphyraena Barracuda)." Zoology 111 (2007): 16-29. 25 Apr. 2008. Paterson, Shane E. "The Great Barracuda." Dances with 'Cudas. 2003. University of Georgia. 30 Apr. 2008 Porter, Heather T., and Phillip J. Motta. "A Comparison of Strike and Prey Capture Kinematics of Three Species of Piscivorous Fishes: Florida Gar (Lepisosteus Platyrhincus), Redfin Needlefish (Strongylura Notata), and Great Barracuda (Sphyraena Barracuda)." Marine Biology 145 (2004): 989-1000. 25 Apr. 2008. "Shark Attacks Down in 2005 But Up Over Long Term." Ichthyology. 21 Feb. 2006. Florida Museum of Natural History. 1 June 2008 Wilson, S. K., D. T. Wilson, C. Lamont, and M. Evans. "Identifying Individual Great Barracuda Sphyraena Barracuda Using Natural Body Marks." Journal of Fish Biology 69 (2006): 928-932. 25 Apr. 2008.
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