- Related Topics:
- tarpon
- Elopoidei
- Megalopidae
- Elops
- Elopidae
elopiform
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What are elopiform fish?
Elopiforms are an order of ray-finned fishes within the superorder Elopomorpha, which is among the most primitive groups of bony fishes. This order includes tarpons and ladyfishes that dwell in marine and brackish waters.
Adult ladyfishes and tarpons are predators, consuming other fish in coastal waters. Tarpons can grow up to 2.5 meters, while ladyfishes average about 1 meter. They are known to roll at the surface to take in air because they have an open duct to their swim bladder.
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Where are elopiform fish found in the world?
Elopiform fishes, belonging to the order Elopiformes, are found in marine and brackish water habitats. The Elopidae family, also known as ladyfishes or tenpounders, has one living genus (Elops) with 5 or 6 species that are circumtropical. The Megalopidae family includes tarpons, with habitats in the Atlantic, Pacific, and Indian oceans.
Adult elopiforms, such as ladyfishes and tarpons, are coastal water predators, primarily feeding on other fish and are also able to enter fresh water. The Pacific tarpon is economically important as food in Southeast Asia.
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What are some examples of elopiform fish species?
Elopiforms are in the order Elopiformes, a group of ray-finned fishes. This order consists of tarpons (Megalops) and ladyfishes (Elops).
Examples of elopiform fish species:
* Atlantic tarpon (Megalops atlanticus) can be found in warm parts of the Atlantic and on the Pacific side of Central America.
* Pacific tarpon (M. cyprinoides) is similar to the Atlantic tarpon.
* Ladyfish (Elops saurus) is a primarily tropical coastal marine fish.Elopiforms are coastal fishes, and adults can enter brackish or fresh water. They are typical predators, feeding mainly on other fishes. The family Elopidae is the only extant teleostean family whose fossil record extends back into the Jurassic Period (199.6 millionā145.5 million years ago).
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What do elopiform fish look like?
Elopiforms are archaic ray-finned fish that include tarpons and ladyfishes. They are coastal fishes, with adults that can enter brackish or fresh water.
Adult ladyfishes and tarpons are typical predators, primarily feeding on other fish. Tarpons can grow up to 2.5 meters, while ladyfish average about 1 meter. The silverfish, or Atlantic tarpon, is known for leaping out of the water, a behavior also seen in Pacific tarpon and ladyfish, possibly to take in air.
Elopiforms possess an open duct to the swim bladder, allowing air taken in at the mouth to pass into it. In tarpons, the swim bladder is lung-like and highly vascularized, making them obligate air breathers. Elopiforms, along with other elopomorphs, have a ribbonlike, translucent, pelagic larva (leptocephalus) that undergoes a striking metamorphosis involving shrinkage to about half the maximum larval size.
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How do elopiform fish live and what do they eat?
Elopiforms are a group of ray-finned fishes that include tarpons and ladyfishes. They are coastal fishes, and adults can enter brackish or fresh water, feeding mainly on other fishes. Tarpons and ladyfishes spawn close to shore, shedding eggs that sink. The juvenile fish consume small crustaceans, insect larvae, and other small animals, before moving back to the sea as young adults.
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Why are elopiform fish important in their ecosystems?
Elopiform fish, including tarpons and ladyfishes, inhabit coastal waters, with adults capable of entering brackish or fresh water. Adult ladyfishes and tarpons act as predators, primarily consuming other fish. The Pacific tarpon is economically significant as a food source, sustaining a substantial fishery in Southeast Asia.
Tarpons possess a lung-like swim bladder that is partially compartmented and highly vascularized. They are obligate air breathers, meaning they will die from asphyxiation if they cannot reach the surface, which is advantageous in the stagnant pools where they spend their postlarval life.
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elopiform, (order Elopiformes), any member of a group of archaic ray-finned fishes that includes the tarpons (Megalops) and the ladyfishes (Elops). Elopiforms live in marine and brackish water habitats. A few are prized game fishes, but only the Pacific tarpon (or oxeye) is of economic importance as food; it supports a major fishery in Southeast Asia. As is usual with primitive groups, the elopiforms have an extensive fossil recordāwith many more fossils than modern species.
Order Elopiformes is one of four orders that make up the superorder Elopomorpha, a group considered to be one of the most primitive of bony fishes (infraclass Teleostei). The other living orders in the superorder include the Anguilliformes (eels), Saccopharyngiformes (bobtail eels, swallowers, and gulpers), and Albuliformes (bonefish). Most taxonomists divide order Elopiformes into the families Elopidae (ladyfishes) and Megalopidae (tarpons).
General features
Elopiforms are coastal fishes, and adults are able to enter brackish or fresh water. Adult ladyfishes (several species of Elops) and tarpons (Megalops) are typical predators of coastal waters, feeding mainly on other fishes. Tarpons grow to adult lengths of up to 2.5 metres (approximately 8 feet), whereas ladyfishes average about 1 metre (about 3 feet). The silverfish, or Atlantic tarpon, (M. atlanticus) is renowned for leaping out of the water; the Pacific tarpon (M. cypinoides) and ladyfishes behave similarly, ārollingā at the surface. The purpose of this behaviour seems to be the intake of air. Like all the other primitive teleosts, the elopiforms possess an open duct to the swim bladder, and air that is taken in at the mouth can be passed into it.
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In tarpons the swim bladder is lunglike, partially compartmented and highly vascularized. Tarpons are obligate air breathers, dying from asphyxiation if prevented from reaching the surface, an unusual condition for a species in which adults normally inhabit well-oxygenated waters. Such an adaptation, however, is certainly advantageous in the stagnant pools where postlarval life is spent. The tarpons exhibit a further modification of the swim bladder, a pair of forward outgrowths that contact the auditory region of the braincase and are partially enclosed in bony bullae, a modification that presumably improves the sense of hearing.
Tarpons and ladyfishes spawn close to shore, and the eggs are shed and fertilized in shoal water, sinking to the bottom. In addition, they are prolific breeders. For example, a large Atlantic tarpon (Tarpon atlanticus) was estimated to contain more than 12 million eggs, about seven times as many as in the proverbially fecund cod.
Elopiforms, along with other elopomorphs, have a ribbonlike, translucent, pelagic larva (leptocephalus) that undergoes a striking metamorphosis involving shrinkage to about half the maximum larval size. The newly hatched leptocephali may be carried out to sea by offshore currents, but metamorphosis only occurs close inshore, and it is probable that larvae carried far out to sea die. During or immediately after their metamorphosis, the postlarvae migrate inland and accumulate in brackish pools or creeks, often connected with open water only at extreme high tide. Such environments are stagnant and low in oxygen, and air breathing is an important aid to survival. The juvenile fish feed on small crustaceans, insect larvae, and other small animals, moving back to the sea as young adults.
Paleontology and classification
Fossil history
The family Elopidae is the only extant teleostean family whose fossil record extends back into the Jurassic Period (199.6 millionā145.5 million years ago). The Late Jurassic genus Anaethalionis is included in this family on the basis of some forms that were extremely similar to the modern Elops. The genera Notelops, from the Early Cretaceous (145.5 millionā99.6 million years ago) of Brazil, and Osmeroides, widely distributed in the seas of the Late Cretaceous (99.6 millionā65.5 million years ago), were probably true elopids. At present the allocation of numerous little-known Cretaceous genera, such as Notelops and Osmeroides, to the family Elopidae, often on the basis of negative evidence, must be considered tentative.
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The earliest known member of the tarpon family appears to be the fossil Sedenhorstia, from the Upper Cretaceous of Europe and Lebanon. Fossils assigned to Megalops appear in Eocene deposits. The earliest member of the extinct suborder Pachyrhizodontoidei is Rhacolepis (from the Lower Cretaceous of Brazil). Rhacolepis was small and resembled the ladyfishes, but later (Upper Cretaceous) members of this group become considerably more specialized. Pachyrhizodus, from the Cretaceous chalks of Europe and North America, exceeded 3 metres (about 10 feet) in length and superficially resembled a tuna. Pachyrhizodontoids may well have been large fast-swimming predators of the open sea, a niche which is now filled by the tunas (Thunnus).
Annotated classification
- Order Elopiformes
- Leptocephalus larva (ribbonlike and translucent, unlike the adult and typically longer); hypurals, when present, on 3 or more centra; branchiostegal rays usually more than 15.
- Suborder Elopoidei
- Mouth terminal and snout unmodified; 2 supramaxillaries; many branchiostegal rays (23ā35); teeth small; large gular plate between the lower jaws; 7 hypural bones.
- Family Elopidae (ladyfish or tenpounder)
- Very generalized fish, the living forms having 32ā35 branchiostegal rays and the swim bladder unmodified. Length to 0.9 metre (about 3 feet); weight to about 13 kg (28.5 pounds). 1 living genus (Elops) with 5 or 6 species; circumtropical. Numerous fossil genera. Late Jurassic to present.
- Family Megalopidae (tarpons)
- Swim bladder partially cellular, lunglike, and connected with the ear; scales large; 23ā25 branchiostegal rays. Length to 2.5 metres (about 8 feet) and weight to 150 kg (about 330 pounds) in M. atlanticus; length to 1.5 metres (5 feet) in M. cyprinoides. 1 living genus (Megalops), 2 species; Atlantic, Pacific, and Indian oceans.
Critical appraisal
Previously, the elopiforms and albuliforms had been classified together as suborders in an enlarged order Elopiformes. The albuliforms are now placed in their own order (Albuliformes). The association between elopiforms and albuliforms was based on only negative evidenceāthat is, the two groups were elopomorph fishes that lacked the eel-like characters of the two other orders (Anguilliformes and Saccopharyngiformes) in the superorder Elopomorpha. Limits among these orders vary from taxonomist to taxonomist. For example, British ichthyologist Peter L. Forey, one of the principal elopomorph taxonomists, and coworkers classify the anguilliforms and saccopharyngiforms together in an expanded Angulliformes.
Placement of the fossil taxa remains particularly problematic. Much work remains to be done to understand the limits and relationships among the fossil and living elopomorph fishes. For example, members of the suborder Crossognathoidei are considered to be part of order Elopiformes by some authorities, such as British paleontologist John G. Maisey, and more derived by others, such as British paleontologist Colin Patterson and American ichthyologist Donn Rosen.