Ladyfishes and Tarpons: Elopiformes

views updated

LADYFISHES AND TARPONS: Elopiformes

ATLANTIC TARPON (Megalops atlanticus): SPECIES ACCOUNT

PHYSICAL CHARACTERISTICS

Tarpons and ladyfishes are long, silver fishes with large upturned mouths, large eyes, and deeply forked tails. They have a long, bony plate between the lower jawbones.

GEOGRAPHIC RANGE

Tarpons and ladyfishes live all over the world.

HABITAT

Tarpons and ladyfishes live in seas that are tropical, meaning that the average annual temperature is more than 68°F (20°C), and subtropical, meaning that the average annual temperature is 55°F to 68°F (13°C to 20°C). They live near the coast, often in estuaries (EHS-chew-air-eez), or the wide parts of rivers where the river meets the sea. Both tarpons and ladyfishes can live in water with a small amount of salt.

DIET

Tarpons and ladyfishes eat fish and crustaceans (krus-TAY-shuns), or water-dwelling animals with shells and jointed legs, such as crabs.

BEHAVIOR AND REPRODUCTION

Tarpons and ladyfishes are predators (PREH-duh-ters), or animals that hunt and kill other animals for food, that feed mainly in open water at middle depths. Both have small, sandpaper-like teeth, and they swallow their catches whole. Tarpons and ladyfishes often live in large schools.

These fishes spawn, or produce and release eggs, offshore in salty ocean water. They produce large numbers of eggs that float on the surface. The eggs hatch into larvae (LAR-vee), or fishes in the early stage of development before they become adults, that have long, clear bodies and fanglike teeth. Larvae of tarpons and ladyfishes reach a length of 1 to 2 inches (2.5 to 5.0 centimeters) before they undergo metamorphosis (meh-tuh-MOR-pho-sus), or change form to become adults. Metamorphosis occurs as the larvae enter coastal waters.

LADYFISHES, TARPONS, AND PEOPLE

Ladyfishes and tarpons are popular for sport fishing. They are not usually eaten.

FISHING FOR TARPONS

Tarpons are known for their spectacular leaps from the water when hooked and for their willingness to enter shallow water and eat artificial (ahr-tuh-FIH-shul), or manmade, baits. Probably more than any other species, tarpons offer anglers in small boats an opportunity to pursue a large game fish. Tarpons are pursued by a large charter boat fleet in Florida.

CONSERVATION STATUS

Tarpons and ladyfishes are not threatened or endangered.

ATLANTIC TARPON (Megalops atlanticus): SPECIES ACCOUNT

Physical characteristics: Atlantic tarpons are bright silver all over, and the back is darker than the sides or belly. These fishes can weigh more than 220 pounds (100 kilograms) and can be more than 6.6 feet (2 meters) long, although the average weight of females is about 110 pounds (50 kilograms) and of males is only 66 pounds (30 kilograms). The body is long and looks flat when viewed from the top. The mouth is very large, and the lower jaw juts out beyond the upper jaw. The scales, or thin, hard plates that cover the skin, are large. The last ray, or supporting rod, of the dorsal (DOOR-suhl) fin, the fin that runs along the top of the body, is very long.

Geographic range: Atlantic tarpons live on both sides of the Atlantic Ocean.

Habitat: Atlantic tarpons live in shallow coastal waters and estuaries. They sometimes enter freshwater, traveling far up rivers and entering lakes far from the sea. Young tarpons live in small, still pools with varying levels of salt and sometimes enter freshwater. Tarpons cannot survive water temperatures less than 55°F (12.8°C). Large numbers of tarpons die during severe cold fronts off Florida.

Diet: Young Atlantic tarpons eat microscopic crustaceans, fishes, shrimps, and mosquito larvae. Adults eat fishes, crabs, and shrimps.

Behavior and reproduction: Atlantic tarpons rise to the surface to breathe air using the swim bladder, an organ usually used for controlling their position in the water. This ability allows tarpons to live in water with small amounts of oxygen, such as hot, still, stale marshes.

Tarpons can live more than fifty years. By one year of age, tarpons are about 18 inches (46 centimeters) long. They start to reproduce at about ten years of age. Large tarpons caught in Florida are about fifteen to thirty-five years old.

In some areas Atlantic tarpons spawn all year; in others spawning takes place in spring and summer. In the western Atlantic, tarpons gather into schools at the beginning of the spawning season and then move together offshore. This behavior may be related to storms or tides. Scientists do not know how many eggs are released at each spawning, but they do know that the ovaries (OH-veh-rees), or egg-producing organs, can contain up to twenty million eggs, so the number released at one time probably is huge.

The larvae of Atlantic tarpons drift toward shore for about thirty days, reaching estuaries when they are about 1 inch (2.5 centimeters) long. During metamorphosis the fishes become smaller than the larvae, but they look like tiny versions of the giant tarpons they will become.

Atlantic tarpons and people: Atlantic tarpons are popular sport fishes, but tarpon is not considered a good food fish.

Conservation status: Atlantic tarpons are not threatened or endangered. ∎