Cape Hatteras is a thin, broken strand of islands in North Carolina that arch out into the Atlantic Ocean away from the US mainland back toward the mainland, creating a series of sheltered islands between the Outer Banks and the mainland. For thousands of years these barrier islands have survived onslaughts of sea. Long stretches of beach, sand dunes and maritime forests create a unique environment where wind and waves shape the topography. A large area of the Outer Banks is part of a National Park, called the Cape Hatteras National Seashore, it is the nearest landmass on the US mainland to Bermuda, about 563 nautical miles to the east-southeast. The treacherous waters off the coast of the Outer Banks is known as the Graveyard of the Atlantic, Over 600 ships wrecked here as victims of shallow shoals and war. Diamond Shoals, a bank of shifting sand ridges hidden beneath the turbulent sea off Cape Hatteras, has never promised safe passage for ships. In the past 400 years the graveyard has claimed many lives.
As early as the 1870s, villagers served in the US Life-Saving Service. Others staffed lighthouses built to guide mariners. Few ships wreck today, but storms still uncover the ruins of the old wrecks that lie along the beaches of the Outer Banks. Cape Hatteras National Seashore protects parts of three barrier islands: Bodie Island, Hatteras Island, Ocracoke Island. Beach and sound access ramps, nature trails, lighthouses can be found and explored on all three islands; the community of Buxton lies on the inland side of the Cape itself, at the widest part of Hatteras Island. It is the largest community on the island, is home to the governmental offices and schools for the Island. Cape Hatteras is a bend in Hatteras Island, one of the long thin barrier islands that make up the Outer Banks, it is the site. The cape's shoals are known as Diamond Shoals. Cape Hatteras has a humid subtropical climate, with long hot summers, short cool winters. Most of the area falls into USDA Plant Hardiness Zone 9. Cape Hatteras is surrounded by water, with Pamlico Sound to the west and the Atlantic Ocean to the east.
The proximity to water moderates conditions throughout the year, producing cooler summers and warmer winters than inland areas of North Carolina. The cape is the northern limit of tropical fauna. During the summer, average daily highs are in the 85 °F range, occasional intense thundershowers occur; as a result of its proximity to water, temperatures above 90 °F are rare, with an average of only 2.3 days annually above 90 °F. The coolest month, has a daily high of 52 °F, with lows well above freezing; the average window for freezing temperatures is from December 12 to March 11, between which there is an average of 21 nights with lows at or below the freezing mark. Extremes in temperature range from 6 °F on January 21, 1985 up to 97 °F on June 27, 1952. Snowfall is observed only and very light. Precipitation in the form of rain, is over 58 inches per year, making it the wettest coastal location in North Carolina. Precipitation is evenly distributed throughout the year; however and May represent a drier season, while August to October are the wettest months.
On average, August is the wettest month, owing to high frequencies of both summer thunderstorms and tropical systems that affect the area from August to early October. Due to its exposed position, Cape Hatteras is the highest-risk area for hurricanes and tropical storms along the entire U. S. Eastern seaboard. Cape Hatteras can experience significant wind and/or water damage from tropical systems moving near or over North Carolina's Outer Banks, while other areas experience much less, minimal or no damage; the Cape Hatteras area is infamous for being struck by hurricanes that move up the East Coast of the United States. The strike of Hurricane Isabel in 2003 was devastating for the area. Isabel devastated the entire Outer Banks and split Hatteras Island between the two small towns of Frisco and Hatteras. NC 12, which provides a direct route from Nags Head to Hatteras Island, was washed out when the hurricane created a new inlet. Students had to use a ferry to get to school; the inlet was filled in with sand by the Army Corps of Engineers which took nearly two months to complete.
The road and water lines were rebuilt when the inlet was filled. The name Hatteras is the sixth oldest surviving English place-name in the U. S. An inlet north of the cape was named "Hatrask" in 1585 by Sir Richard Grenville, the admiral leading the Roanoke Colony expedition sent by Sir Walter Raleigh, it was applied to the island and cape as well, modified to "Hatteras." Hatteras is the name of the Hatteras Indians. Because mariners utilize ocean currents to speed their journey, many ships venture close to Cape Hatteras when traveling along the eastern seaboard, risking the perils of sailing close to the shoals amid turbulent water and the frequent storms occurring in the area. So many ships have been lost off Cape Hatteras that the area is known as the "Graveyard of the Atlantic." Cape Hatteras is well known for surfing. The first lighthouse at the cape was built in 1803.
Fish are gill-bearing aquatic craniate animals that lack limbs with digits. They form a sister group to the tunicates. Included in this definition are the living hagfish and cartilaginous and bony fish as well as various extinct related groups. Tetrapods emerged within lobe-finned fishes, so cladistically they are fish as well. However, traditionally fish are rendered paraphyletic by excluding the tetrapods; because in this manner the term "fish" is defined negatively as a paraphyletic group, it is not considered a formal taxonomic grouping in systematic biology, unless it is used in the cladistic sense, including tetrapods. The traditional term pisces is considered a typological, but not a phylogenetic classification; the earliest organisms that can be classified as fish were soft-bodied chordates that first appeared during the Cambrian period. Although they lacked a true spine, they possessed notochords which allowed them to be more agile than their invertebrate counterparts. Fish would continue to evolve through the Paleozoic era.
Many fish of the Paleozoic developed external armor. The first fish with jaws appeared in the Silurian period, after which many became formidable marine predators rather than just the prey of arthropods. Most fish are ectothermic, allowing their body temperatures to vary as ambient temperatures change, though some of the large active swimmers like white shark and tuna can hold a higher core temperature. Fish can communicate in their underwater environments through the use of acoustic communication. Acoustic communication in fish involves the transmission of acoustic signals from one individual of a species to another; the production of sounds as a means of communication among fish is most used in the context of feeding, aggression or courtship behaviour. The sounds emitted by fish can vary depending on the stimulus involved, they can produce either stridulatory sounds by moving components of the skeletal system, or can produce non-stridulatory sounds by manipulating specialized organs such as the swimbladder.
Fish are abundant in most bodies of water. They can be found in nearly all aquatic environments, from high mountain streams to the abyssal and hadal depths of the deepest oceans, although no species has yet been documented in the deepest 25% of the ocean. With 33,600 described species, fish exhibit greater species diversity than any other group of vertebrates. Fish are an important resource for humans worldwide as food. Commercial and subsistence fishers hunt fish in wild fisheries or farm them in ponds or in cages in the ocean, they are caught by recreational fishers, kept as pets, raised by fishkeepers, exhibited in public aquaria. Fish have had a role in culture through the ages, serving as deities, religious symbols, as the subjects of art and movies. Fish do not represent a monophyletic group, therefore the "evolution of fish" is not studied as a single event. Early fish from the fossil record are represented by a group of small, armored fish known as ostracoderms. Jawless fish lineages are extinct.
An extant clade, the lampreys may approximate ancient pre-jawed fish. The first jaws are found in Placodermi fossils; the diversity of jawed vertebrates may indicate the evolutionary advantage of a jawed mouth. It is unclear if the advantage of a hinged jaw is greater biting force, improved respiration, or a combination of factors. Fish may have evolved from a creature similar to a coral-like sea squirt, whose larvae resemble primitive fish in important ways; the first ancestors of fish may have kept the larval form into adulthood, although the reverse is the case. Fish are a paraphyletic group: that is, any clade containing all fish contains the tetrapods, which are not fish. For this reason, groups such as the "Class Pisces" seen in older reference works are no longer used in formal classifications. Traditional classification divides fish into three extant classes, with extinct forms sometimes classified within the tree, sometimes as their own classes: Class Agnatha Subclass Cyclostomata Subclass Ostracodermi † Class Chondrichthyes Subclass Elasmobranchii Subclass Holocephali Class Placodermi † Class Acanthodii † Class Osteichthyes Subclass Actinopterygii Subclass Sarcopterygii The above scheme is the one most encountered in non-specialist and general works.
Many of the above groups are paraphyletic, in that they have given rise to successive groups: Agnathans are ancestral to Chondrichthyes, who again have given rise to Acanthodiians, the ancestors of Osteichthyes. With the arrival of phylogenetic nomenclature, the fishes has been split up into a more detailed scheme, with the following major groups: Class Myxini Class Pteraspidomorphi † Class Thelodonti † Class Anaspida † Class Petromyzontida or Hyperoartia Petromyzontidae Class Conodonta † Class Cephalaspidomorphi † Galeaspida † Pituriaspida † Osteostraci † Infraphylum Gnathostomata Class Placodermi † Class Chondrichthyes Class Acanthodii † Superclass Osteichthy
A sailfish is a fish of the genus Istiophorus of billfish living in colder areas of all the seas of the earth. They are predominantly blue to gray in colour and have a characteristic dorsal fin known as a sail, which stretches the entire length of the back. Another notable characteristic is the elongated bill, resembling that of the swordfish and other marlins, they are, described as billfish in sport-fishing circles. Two sailfish species have been recognized. No differences have been found in mtDNA, morphometrics or meristics between the two supposed species and most authorities now only recognized a single species, found in warmer oceans around the world. FishBase continues to recognize two species: Atlantic sailfish. Indo-Pacific sailfish. Sailfish grow reaching 1.2–1.5 m in length in a single year, feed on the surface or at middle depths on smaller pelagic forage fish and squid. Sailfish were estimated to reach maximum swimming speeds of 35 m/s, but research published in 2015 and 2016 indicate sailfish do not exceed speeds between 10–15 m/s.
During predator–prey interactions, sailfish reached burst speeds of 7 m/s and did not surpass 10 m/s. Sailfish do not grow to more than 3 m in length and weigh over 90 kg. Sailfish have been reported to use their bills for hitting schooling fish by tapping or slashing at them; the sail is kept folded down when swimming and raised only when the sailfish attack their prey. The raised sail has been shown to reduce sideways oscillations of the head, to make the bill less detectable by prey fish; this strategy allows sailfish to put their bills close to fish schools or into them without being noticed by the prey before hitting them. Sailfish attack one at a time, the small teeth on their bills inflict injuries on their prey fish in terms of scale and tissue removal. About two prey fish are injured during a sailfish attack, but only 24% of attacks result in capture; as a result, injured fish increase in number over time in a fish school under attack. Given that injured fish are easier to catch, sailfish benefit from the attacks of their conspecifics but only up to a particular group size.
A mathematical model showed that sailfish in groups of up to 70 individuals should gain benefits in this way. The underlying mechanism was termed protoco-operation because it does not require any spatial co-ordination of attacks and could be a precursor to more complex forms of group hunting; the bill movement of sailfish during attacks on fish is either to the left or to the right side. Identification of individual sailfish based on the shape of their dorsal fins identified individual preferences for hitting to the right or left side; the strength of this side preference was positively correlated with capture success. These side-preferences are believed to be a form of behavioural specialization that improves performance. However, a possibility exists that sailfish with strong side preferences could become predictable to their prey because fish could learn after repeated interactions in which direction the predator will hit. Given that individuals with right- and left-sided preferences are about frequent in sailfish populations, living in groups offers a way out of this predictability.
The larger the sailfish group, the greater the possibility that individuals with right- and left-sided preferences are about frequent. Therefore, prey fish should find it hard to predict in which direction the next attack will take place. Taken together, these results suggest a potential novel benefit of group hunting which allows individual predators to specialize in their hunting strategy without becoming predictable to their prey; the injuries that sailfish inflict on their prey appear to reduce their swimming speeds, with injured fish being more found in the back of the school than uninjured ones. When a sardine school is approached by a sailfish, the sardines turn away and flee in the opposite direction; as a result, the sailfish attacks sardine schools from behind, putting at risk those fish that are the rear of the school because of their reduced swimming speeds. Schultz, Ken Ken Schultz's Field Guide to Saltwater Fish pp. John Wiley & Sons. ISBN 9780471449959. Images from National Geographic
The common snook is a species of marine fish in the family Centropomidae of the order Perciformes. The common snook is known as the sergeant fish or robalo, it was assigned to the sciaenid genus Sciaena. One of the largest snooks, C. undecimalis grows to a maximum overall length of 140 cm, but common length is 50 cm. The IGFA world record is 24.32 kg caught in Costa Rica, by Rafael Montalvo. Of typical centropomid form, it possesses drab coloration except for a distinctive black lateral line, it can have bright yellow pelvic and caudal fins during spawn. The common snook is a protandric hermaphrodite fish species; the common snook’s spawning season appears to span the months of April to October, with the peak spawning occurring during July and August. Spawning occurs in near-shore waters with high salinities. Following the spawning period, the juveniles migrate to the brackish waters of the nearby estuarine environments; when these juveniles mature, they return to the higher-salinity waters of the open ocean to join the breeding population.
The common snook is an estuarine-dependent fish species. Within estuaries, juvenile common snook are most found inhabiting areas such as coastal wetland ponds, island networks, creeks. Despite being a euryhaline species of fish, the common snook does show a tendency to gravitate towards lower-salinity conditions in the early stages of its life. By being able to adapt and thrive in both high- and low-salinity conditions through osmoregulation, common snook display a high level of habitat plasticity. Common snook are opportunistic predators whose feeding habits indicate a positive relationship between their size and the size of their prey, meaning that as the snook grows, it feeds on larger and larger prey. Common snook have been found to engage in cannibalism, though this behavior is rare; this occurs during the winter when adult and juvenile common snook are in close proximity to one another within their estuarine habitats. This form of cannibalism where the juveniles are fed on by the adults is referred to as intercohort cannibalism.
The adult common snook that do cannibalize juveniles most target them because the juveniles may be the largest of the available prey, so are nutritionally efficient to prey upon. Common snook, like many species of fish, are in tune with their environments. For example, common snook are able to determine when to start and stop spawning based on the temperature and salinity of the water they inhabit, the amount of rainfall in the area, whether or not the moon is full. However, in some cases, disturbances in their environment can have negative effects on the snook population. One example is the devastating results of a cold snap. Snook are susceptible to cold temperatures, with the effects ranging from the complete halt of all feeding at a water temperature of 14.2 °C, to the loss of equilibrium at 12.7 °C, to death at a temperature of 12.5 °C. A cold snap in January 2010 resulted in a 41.88% decline in nominal abundance of the common snook population in southwest Florida from the previous year and a 96-97% decrease in apparent survival estimates.
C. undecimalis is widespread throughout the tropical waters of the western Atlantic Ocean from the coast of the North Carolina to Brazil including the Gulf of Mexico and the Caribbean Sea. Snook originated in Central America, changes in the earth’s climate brought the snook to Florida. During a great warming trend after the Ice Age, snook moved northward along the Mexico shoreline, they followed the perimeter of the Gulf of Mexico, along east coasts of Florida. Massive snook are found in Central America, although they seem to look a little different because of the weather and water quality, but they are the same. No restrictions exist in most of Central America on the size or quantity of snook one can keep many locals have been keeping and killing these large snook for quite a while. Occurring in shallow coastal waters and lagoons, the fish enter fresh water, they are carnivorous, with a diet dominated by smaller fishes, crustaceans such as shrimp, crabs. Three United States Navy submarines have been named for this species, USS Robalo and USS Snook in the Second World War and USS Snook in the 1950s.
Considered an excellent food fish, the common snook is fished commercially and foreign-caught fish are sold in the US. When cooking snook, the skin must be removed, because it imparts an unpleasant taste, described as soapy, to the fish. Snook are prized as game fish, being known for their great fighting capabilities; the IGFA All Tackle World Record for Common snook stands at 53lb 10oz caught by Gilbert Ponzi near Parismina Ranch, Costa Rica. Previous world records were caught in Fort Myers and Gatun Spillway Canal Zone, Panama. "At the June 2012 Florida Fish and Wildlife Conservation Commission meeting, Commissioners voted to keep the recreational harvest of snook in Gulf of Mexico waters closed through Aug. 31, 2013. This closure will offer the species additional protection after a 2010 cold kill detrimentally affected the population. Snook closed to harvest in Gulf of Mexico and Atlantic waters in January 2010 after a severe cold kill affected snook population number."All snook are "catch-and-release only" in the Gulf of Mexico until August 31, 2013.
At that time, the FWC can choose to open or close snook harvest for ano
Thymallus is a genus of freshwater fish in the salmon family Salmonidae. The type species is the grayling; the species in the genus are generically called graylings, but without qualification this refers to T. thymallus. The fishes of this genus are native to the northern parts of the Palearctic and Nearctic ecozones, ranging from the United Kingdom and northern Europe across Eurasia to Siberia, as well as northern North America. T. thymallus, the grayling, is widespread in Europe, T. arcticus, the Arctic grayling, is widespread throughout Eurasia east of the Ural Mountains and in the Nearctic. The other species have more localized ranges in northern Asia. Thymallus species are distinguished from other members of the salmon family by their larger scales, their small mouths with teeth on the maxillary bone, most striking of all, their showy, sail-like dorsal fins; this fin is longer in males and colourful, with spots of red, purple or green. The body is colourful; the body is further decorated with a smattering of small dark spots.
The longest of the graylings is the Arctic grayling, T. arcticus, at a maximum length of 76 cm and a maximum weight of 3.8 kg. T. thymallus, while somewhat shorter - 60 cm - may weigh more, 6.7 kg. The fishes of this genus may live for 18 years or more; these fishes require well-oxygenated water, preferably with a swift current. Omnivorous, they feed on crustaceans and zooplankton; the grayling species for salmonids, spawn in rivers and do not guard their brood, although they do conceal their eggs in silt. The spawning behavior of the Arctic grayling may be typical for the genus Thymallus; as they are sensitive to changes in water quality, Thymallus fishes may be considered indicator species. Due to their agreeable taste and attractive form, the grayling species are valued as food and game fishes, they are seen in public aquaria; the most economically important of these fishes, for which fisheries and aquaculture operations exist, are the grayling and the Arctic grayling. The name of the genus Thymallus first given to grayling described in the 1758 edition of Systema Naturae by Swedish zoologist Carl Linnaeus originates from the faint smell of the herb thyme, which emanates from the flesh.
Thymallus derives from the Greek θύμαλλος, "thyme smell". According to FishBase, 14 species are placed in this genus. However, views differ on their taxonomic rank. Thymallus arcticus - Arctic grayling Thymallus baicalensis Dybowski, 1874 - Baikal black grayling Thymallus brevipinnis Svetovidov, 1931 - Baikal white grayling Thymallus brevirostris Kessler, 1879 - Mongolian grayling Thymallus burejensis Antonov, 2004 Thymallus flavomaculatus Knizhin, Antonov & Weiss, 2006 - yellow-spotted grayling Thymallus grubii Dybowski, 1869 - Amur grayling Thymallus mertensii Valenciennes, 1848 Thymallus nigrescens Dorogostaisky, 1923 - Kosogol grayling Thymallus pallasii Valenciennes, 1848 - East Siberian grayling Thymallus svetovidovi Knizhin & Weiss, 2009 - Upper Yenisei grayling Thymallus thymallus - grayling Thymallus tugarinae Knizhin, Safronov & Weiss, 2007 - Lower Amur grayling Thymallus yaluensis T. Mori, 1928The Catalog of Fishes lists the species Thymallus baikalolenensis Matveyev, Pronin & Telpukhovsky, 2005, but recognises T. yaluensis only as a subspecies.
An old controversy exists over the status of Baikal black vs white graylings, T. baicalensis and T. brevipinnis. Modern research supports the view that they are not separate taxa, but alternative ecological forms of T. baicalensis. "Thymallus". Integrated Taxonomic Information System. Retrieved 11 December 2004. Dyldin, Y. V.. I. Romanov. "A review of the genus Thymallus with taxonomic notes". Bulletin Lampetra. VIII: 103–126
In biology or human geography, population growth is the increase in the number of individuals in a population. Many of the world's countries, including many in Sub-Saharan Africa, the Middle East, South Asia and South East Asia, have seen a sharp rise in population since the end of the Cold War; the fear is that high population numbers are putting further strain on natural resources, food supplies, fuel supplies, housing, etc. in some of the less fortunate countries. For example, the population of Chad has grown from 6,279,921 in 1993 to 10,329,208 in 2009, further straining its resources. Vietnam, Nigeria, Egypt and the DRC are witnessing a similar growth in population. Global human population growth amounts to 1.1 % per year. The global population has grown from 1 billion in 1800 to 7.616 billion in 2018. It is expected to keep growing, estimates have put the total population at 8.6 billion by mid-2030, 9.8 billion by mid-2050 and 11.2 billion by 2100. Many nations with rapid population growth have low standards of living, whereas many nations with low rates of population growth have high standards of living.
Population began growing in the Western world early in the industrial revolution of the late 18th century. The reasons for the "Modern Rise of Population" were investigated by the British health scientist Thomas McKeown. In his publications, McKeown challenged four theories about the population growth: McKeown stated that the growth in Western population surging in the 19th century, was not so much caused by an increase in fertility, but by a decline of mortality of childhood mortality followed by infant mortality, The decline of mortality could be attributed to rising standards of living, whereby McKeown put most emphasis on improved nutritional status, His most controversial idea, at least his most disputed idea, was that he questioned the effectiveness of public health measures, including sanitary reforms and quarantine, The sometime fierce disputes that his publication provoked around the "McKeown thesis", have overshadowed his more important and unchallenged argument that curative medicine measures played little role in mortality decline, not only prior to the mid-20th century but until well into the 20th century.
Although the McKeown thesis has been disputed, recent studies have confirmed the value of his ideas. His work is pivotal for present day thinking about population growth, birth control, public health and medical care. McKeown had a major influence on many population researchers, such as health economists and Nobel prize winners Robert W. Fogel and Angus Deaton; the latter considered McKeown as "the founder of social medicine". The "population growth rate" is the rate at which the number of individuals in a population increases in a given time period, expressed as a fraction of the initial population. Population growth rate refers to the change in population over a unit time period expressed as a percentage of the number of individuals in the population at the beginning of that period; this can be written as the formula, valid for a sufficiently small time interval: P o p u l a t i o n g r o w t h r a t e = P − P P A positive growth rate indicates that the population is increasing, while a negative growth rate indicates that the population is decreasing.
A growth ratio of zero indicates that there were the same number of individuals at the beginning and end of the period—a growth rate may be zero when there are significant changes in the birth rates, death rates, immigration rates, age distribution between the two times. A related measure is the net reproduction rate. In the absence of migration, a net reproduction rate of more than 1 indicates that the population of females is increasing, while a net reproduction rate less than one indicates that the population of females is decreasing. Most populations do not grow exponentially. Once the population has reached its carrying capacity, it will stabilize and the exponential curve will level off towards the carrying capacity, when a population has depleted most its natural resources; the growth of a population can be modelled by the logistic equation d P d t = r P, where P = the population after time t. As it is a separable differential equation, the population may be solved explicitly, producing a logistic function: P ( t
Tarpons are large air-breathing fish of the genus Megalops. They are the only members of the family Megalopidae; the two species of tarpons are the Megalops cyprinoides. M. atlanticus is found on the western Atlantic coast from Virginia to Brazil, throughout the coast of the Gulf of Mexico, throughout the Caribbean. Tarpons are found along the eastern Atlantic coast from Senegal to South Angola. M. cyprinoides is found along the eastern African coast, throughout southeast Asia, Japan and Australia. Both species are found in both saltwater and freshwater habitats ascending rivers to access freshwater marshes, they are able to survive in brackish water, waters of varying pH, habitats with low dissolved O2 content due to their swim bladders, which they use to breathe. They are able to rise to the surface and take gulps of air, which gives them a short burst of energy; the habitats of tarpon vary with their developmental stages. Stage-one larvae are found in clear, oceanic waters close to the surface.
Stage-two and -three larvae are found in salt marshes, tidal pools and rivers. The habitats are characteristically warm, dark bodies of water with sandy mud bottoms. Tarpon ascend rivers into freshwater; as they progress from the juvenile stage to adulthood, they move back to the open waters of the ocean, though many remain in freshwater habitats. Tarpons weigh 27 - 127 kilograms, they have bluish or greenish backs. Tarpons possess silvery scales that cover most of their bodies, excluding the head, they have large eyes with adipose eyelids and broad mouths with prominent lower jaws that jut out farther than the rest of the face. Tarpons breed offshore in isolated areas. Females can lay up to 12 million eggs at once, they reach sexual maturity. Spawning occurs in late spring to early summer, their three distinct levels of development occur in varying habitats. The first stage, the leptocephalus stage, or stage one, is completed after 20–30 days, it takes place in clear, warm oceanic waters within 10–20 m of the surface.
The leptocephalus shrinks. This is due to a negative growth phase followed by a sluggish growth phase. By day 70, the juvenile growth phase, stage three and the fish begins to grow until it reaches sexual maturity. Stage-one developing Megalops do not forage for food, but instead absorb nutrients from seawater using integumentary absorption. Stage-two and -three juveniles feed on zooplankton, but feed on insects and small fish; as they progress in juvenile development those developing in freshwater environments, their consumption of insects, fish and grass shrimp increases. Adults are carnivorous and feed on midwater prey; the main predators of Megalops during stage one and early stage-two development are other fish, depending on their size. Juveniles are subject to predation by other juvenile piscivorous birds, they are vulnerable to birds when they come to the surface for air, due to the rolling manner in which they move to take in air, as well as the silver scales lining their sides. Adults fall prey to sharks, porpoises and alligators.
One of the unique features of Megalops is the swim bladder, which functions as a respiratory pseudo-organ. This gas structure can be used as an accessory respiratory organ, or both. In Megalops, this unpaired air-holding structure arises dorsally from the posterior pharynx. Megalops uses the swim bladder as a respiratory organ and the respiratory surface is coated with blood capillaries with a thin epithelium over the top; this is the basis of the alveolar tissue found in the swim bladder, is believed to be one of the primary methods by which Megalops “breathes”. These fish are obligate air breathers, if they are not allowed to access the surface, they will die; the exchange of gas occurs at the surface through a rolling motion, associated with Megalops sightings. This “breathing” is believed to be mediated by visual cues, the frequency of breathing is inversely correlated to the dissolved O2 content of the water in which they live. Megalops is considered one of the great saltwater game fishes.
They are prized not only because of their great size, but because of the fight they put up and their spectacular leaping ability. They are bony fish and their meat is not desirable, so most are released after they are caught. Numerous tournaments around the year are focused on catching tarpon. Since tarpons are not commercially valuable as a food fish little has been documented concerning their geographical distribution and migrations, they inhabit both sides of the Atlantic Ocean, their range in the eastern Atlantic has been reliably established from Senegal to the Congo. Tarpons inhabiting the western Atlantic are principally found to populate warmer coastal waters in the Gulf of Mexico and the West Indies. Nonetheless, tarpons are caught by anglers at Cape Hatteras and as far as Nova Scotia and south to Argentina. Scientific studies indicate schools of tarpons have migrated through the Panama Canal from the Atlantic to the Pacific and back for over 70 years. However, they have not been found to breed in the Pacific Ocean.