|Copyright: Alfredo Wang (alfhwa)
|Date Taken: 2007-10-25|
|Camera: Olympus Stylus 770SW|
|Exposure: f/3.5, 1/250 seconds|
|More Photo Info: [view]|
|Photo Version: Original Version|
|Date Submitted: 2007-11-09 5:48|
|[Note Guidelines] Photographer's Note|
|We found this Tarpon swimming very next to us in Cinnamon Bay, very close to the island (so, a bit of a swim from the safety of the beach). The fish is roughly 1.5 meters in length (about 5 feet long), larger than most kids and even some adults snorkeling nearby. For a first-timer (like us), it was pretty intimidating.|
Very next to the Tarpon, you can see a swarm of small fishes that eventually would be his dinner.
Order - Elopiformes
Family - Megalopidae (Elopidae)
Genus - Megalops
Species - atlanticus
Tarpon inhabit a large range on both sides of the Atlantic Ocean. The range in the Eastern Atlantic extends from Senegal to the Congo. In the Western Atlantic, the fish primarily inhabit warmer coastal waters concentrating around the Gulf of Mexico, Florida, and the West Indies. However, tarpon are not uncommon as far north as Cape Hatteras, and the extreme range extends from Nova Scotia in the north, Bermuda, and to Argentina to the south. Tarpon have been found at the Pacific terminus of the Panama Canal and around Coiba Island.
Tarpon populate a wide variety of habitats, but are primarily found in coastal waters, bays, estuaries, and mangrove-lined lagoons within tropical, subtropical, and temperate climates (45° N-30° S). The normal habitat depth extends to 98 feet (30 m). Although a marine fish, tarpon can tolerate euryhaline environments (0-47 parts per thousand) and often enter river mouths and bays and travel upstream into fresh water. In addition, tarpon can also tolerate oxygen-poor environments due to a modified air bladder that allows them to inhale atmospheric oxygen. The only variable that seems to limit their choice of habitat is temperature, and research shows tarpon to be thermophilic. Rapid decreases in temperature have been known to cause large tarpon kills. During such temperature drops, tarpon usually take refuge in warmer deeper waters.
Externally, the almost vertical, silvery sides made up of large scales are the most distinctive feature of the tarpon. The tarpon has a superior mouth with the lower mandible extending far beyond the gape. The fins contain no spines, but are all composed of softrays. The dorsal fin appears high anteriorly and contains 13-15 softrays with the last ray greatly elongated into a heavy filament. The caudal is deeply forked, and the lobes appear equal in length. The anterior portion of the anal fin is deep and triangular. The fin has 22-25 softrays, with the last ray again elongated as in the dorsal fin, but shorter and only present in adults. The tarpon has large pelvic fins, and long pectoral fins containing 13-14 softrays.
Perhaps the most unique internal feature of the tarpon is the modified swim bladder. This swim bladder contains spongy alveolar tissue and has a duct leading to the esophagus that the tarpon may fill directly with air gulped from the surface. This feature allows the tarpon to take oxygen directly from the atmosphere and increases its tolerance of oxygen-poor waters. In fact, studies have shown that tarpon must have access to atmospheric oxygen in order to survive, and that juvenile tarpon are obligatory air-breathers. Adults living in oxygen-rich waters still roll and gulp air, probably as an imitative pattern based on visual perception of other tarpon.
Female tarpon can grow to lengths of over 8.2 feet (2.5m) and reach weights of near 355 pounds (161 kg), with the males generally smaller. Tarpon are slow-growing fish and do not obtain sexual maturity until reaching an age of 6-7 years and a length of about 4 feet (1.2 m). Tarpon weighing about 100 pounds (45.4 kg) typically fall between 13-16 years of age. Male tarpon attain lifespans of over 30 years, while females may live longer than 50 years. A female tarpon held in captivity at the John G. Shedd Aquarium in Chicago, Illinois died in 1998 at the age of 63.
The tarpon employs different feeding techniques depending upon its level of growth and development. Stage I larvae absorb nutrients directly from seawater through the integument. Zooplankton (copepods and ostracods), insects, and small fish compose the diet of stage II and III tarpon larvae and small juveniles. As tarpon grow, they move away from zooplankton as a chief food source and prey more exclusively on fishes (especially poecilids and cyprinodontids) and larger invertebrates such as shrimp and crabs. While juvenile tarpon are planktivorous, adult tarpon are strictly carnivorous and mostly feed on mid-water prey such as mullets, pinfish, marine catfishes, Atlantic needlefish, sardines, shrimp, and crabs. Tarpon feed during both day and night. Since the tarpon have minute teeth only, they usually swallow the prey whole.
Zooplankton and small fishes prey on tarpon in the egg and larval stages, and piscivorous birds are primary predators of juvenile tarpon once they enter nursery areas. Sharks, e.g. bull and hammerhead, are the main predators of adult tarpon, but porpoises and alligator also prey on the fish.
Source: Florida Museum of Natural History
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