Beloniformes

(Needlefishes and relatives)

Class Actinopterygii

Order Beloniformes

Number of families 5

Evolution and systematics

The Beloniformes is one of three orders within the series Atherinomorpha. One of the other two orders, the Atheriniformes, is thought by some ichthyologists to represent an unnatural grouping of several lineages, while others consider it monophyletic (a natural group). The other order, Cyprinodontiformes, is the sister-group of the Beloniformes, as evidenced by numerous internal characters, including modifications to the gill arches and the bones surrounding the eyes. Both Cyprinodontiformes and Beloniformes are agreed to be monophyletic. Beloniformes themselves are united by derived internal characters of the gill arches rather than any conspicuous external morphological characters. Five families of fishes make up the order Beloniformes: Adrianichthyidae (ricefishes), Belonidae (needlefishes), Scomberesocidae (sauries), Exocoetidae (flyingfishes), and Hemiramphidae (halfbeaks). Within these families are 38 genera and about 200 species, 51 of which are either brackish or freshwater, the remainder of which are marine.

The earliest known fossil Beloniformes are just over 50 million years old, and come from two sites: the exocoetids from Monte Bolca in Italy, and the hemiramphids from the Selsey formation in England. Beloniformes are broadly divided into two suborders, the Exocoetoidei (beaked forms: belonids, scomberesocids, exocoetids, and hemiramphids) and the Adrianichthyoidei (lacking a beak; adrianichthyids). Adrianichthyids were traditionally included within the Cyprinodontiformes until Rosen and Parenti argued for their inclusion within the Beloniformes in 1981, based mainly on characters of the gill arches and hyoid apparatus. Adrianichthyids are now considered to be the sister lineage to the rest of the order, within which the sister groups Belonidae-Scomberesocidae and Hemiramphidae-Exocoetidae have been suggested.

Contrary to this scheme, a study based on morphology and molecules, published in 2000 by Lovejoy, places halfbeaks as the ancestral form among the beaked beloniforms. In Love-joy's tree, some halfbeaks are most closely related to needle-fishes and sauries, while the marine halfbeak Hemiramphus is sister to flyingfishes. This result refutes an old hypothesis, based on the observation that needlefishes pass through a half-beak stage during their development, that halfbeaks derive from needlefishes via truncation of the development sequence.

Physical characteristics

Beloniformes are typically elongate fishes, with dorsal and anal fins situated posteriorly on the body and the lateral line situated ventrally. Additional characteristics of the group include fusion of the toothed 5th ceratobranchials into a lower pharyngeal jaw and an open nasal pit. Belonids, aptly called needlefishes, are sleek and garlike piscivores, with very long upper and lower jaws studded with sharp teeth. They can achieve lengths of up to 3.3 ft (1 m). A small number of needle-fishes have a reduced upper jaw, and like halfbeaks, feed on plankton and insects. Scomberesocids, of which the largest are about 1.65 ft (0.5 m) long, can be distinguished from belonids by the five or six finlets behind their dorsal and anal fins. The diminutive scomberesocid Cololabis adocetus, at 3 in (7.5 cm), is the smallest fish in the surface waters of the open ocean.

In most species of hemiramphids, or halfbeaks, the lower jaw is much longer than the upper. The front margin of the upper jaw is triangular in shape, the scales are large and cycloid, and fin spines are lacking. Exocoetids, the flyingfishes, are torpedo shaped with greatly enlarged pectoral fins, and the lower lobe of the caudal fin is stiffened and much larger than the upper. Interestingly, the most primitive flyingfish genera, Oxyporhamphus (once included with hemiramphids),

Fodiator, and Parexocoetus, have elongate lower jaws reminiscent of halfbeaks. More derived flyingfishes have acquired oversized pelvic fins in addition to large pectoral fins, and are called four-wingers.

Adrianichthyids, the most basal among the Beloniformes, are superficially unlike other members of the group. Most of the species are in the genus Oryzias, and are small, relatively deep-bodied fishes with large eyes, upturned mouths, and a long anal fin base. Noteworthy in the family is the duckbilled buntingi (Adrianichthys kruyti), which has a bill-shaped mouth with the upper jaw overhanging the lower. Xenopoecilus species also have a bill-shaped mouth, and the carry their eggs at the base of the pelvic fins by way of filamentous attachments.

Distribution

Beloniformes are widely distributed in temperate and tropical marine and fresh waters. Adrianichthyids are found in Asian fresh and brackish waters from India to Japan, and in the Indo-Australian archipelago. Belonids are found in the open ocean in tropical and temperate seas worldwide, with numerous species in the freshwaters of South America and some in Asia. Like marine belonids, scomberesocids are widely distributed in warmer waters of the open ocean. Exocoetids are found in warm waters of the Atlantic, Pacific, and Indian Oceans. Hemiramphids have a similar distribution in marine waters, but have also invaded freshwaters, especially in the Indo-Australian region.

Habitat

Marine beloniforms can be found in the surface waters of the open ocean, as well as in coastal habitats like estuaries and mangrove swamps. Adrianichthyids, belonids, and hemiramphids can be found in a diversity of tropical freshwater habitats, including lakes and rivers.

Behavior

One characteristic of many beloniforms is a strong attraction to lights at night. This behavior is exploited by fishermen, who use lights to capture schools of sauries that cruise just below the ocean surface. Such fishing methods, however, involve a peculiar (although infrequent) hazard: impalement by large needlefishes. In one documented case, a 3.3 ft (1 m) long Tylosurus fatally impaled a fisherman after jumping toward the light on board his canoe.

Certainly the most remarkable beloniform behavior is exocoetid flight. (It should be noted that flight is not entirely restricted to exocoetids: Some hemirhamphids are capable of gliding, and Euleptorhamphus viridis has been reported to travel 164 ft [50 m] in two jumps.) In the more derived four-winged flyingfish species, flight is achieved as follows. The fish, swimming at a speed of about 33 ft/s (10 m/s), breaks the surface at an oblique angle and taxis for 16.4–82 ft (5–25 m) by rapidly beating the caudal fin in the water. Then a free flight ensues, which may span a distance of 164 ft (50 m) and reach a height of 26.2 ft (8 m). Once the fish loses altitude, caudal fin taxiing can be repeated without returning to the water, so that flights can be stretched to distances of 1,312 ft (400 m). Intriguingly, flyingfishes seem to sense wind direction and take off into the wind, and tantalizing evidence suggests that they can control the direction of flight; Cypsilurus appear to successfully seek out patches of seaweed in which to land. So why do flyingfishes fly? One of the most likely hypotheses is that flight has evolved as a tactic for evading predators.

Feeding ecology and diet

Beloniformes utilize a relatively wide spectrum of foods. Most impressive perhaps are the marine needlefishes, which cruise through the surface waters of the open ocean devouring small fishes. However, not all needlefishes are piscivores. In the Amazon, many belonids feed heavily on zooplankton or insects. Belonion apodion, which grows only to about 2 in (5 cm), is unusual in that it deftly snaps up individual rotifers, which are less than 0.004 in (0.1 mm) long and usually pass through the gill rakers of filter-feeding planktivorous fishes. Potamorrhaphis, which prefers terrestrial insects (especially flying ants), hovers motionlessly and waits for prey to fall to the surface alongside its body. Then it rapidly curls the body and strikes at the prey from the side.

Freshwater halfbeaks also feed on terrestrial insects, and some are particularly well suited to this mode of feeding. Members of the genus Hemirhamphodon are noteworthy for having numerous anteriorly directed teeth on their lower jaws, which ensnare ants and other insects found floating on the surface. Marine halfbeaks, on the other hand, tend to feed on algae, diatoms, and sea grasses, though some species eat small fishes. Planktivorous marine beloniforms include the flyingfishes and sauries. Ricefishes are omnivorous and will eat plankton, small insects, detritus, and plant material.

Beloniformes themselves often fall prey to larger fishes. Flyingfishes in particular are eaten by mackerel, tuna, and marlin, among other predatory fishes, as well as squids and birds.

Reproductive biology

Much of what is known about beloniform reproductive biology involves the eggs and larvae. Typically, eggs develop in one to two weeks, and the larvae are immediately able to feed upon hatching. Many pelagic beloniform eggs have filamentous projections that cause them to stick to floating debris. Needlefish eggs have tendrils that are particularly sticky, and they form egg clusters that stick to other objects in the water. Likewise, sauries produce filamentous eggs that float in open water, but they are less adhesive than needlefish eggs. Flyingfishes lay pelagic eggs that may or may not have filaments, and some species attach their eggs to floating seaweed. Marine halfbeaks lay eggs with tendrils that float about in open water, but some freshwater representatives bear live young, namely Dermogenys, Nomorhamphus, and Hemirhamphodon. In these viviparous forms, long genital papillae are used for internal fertilization, and the male anal fin is modified into an andropodium.

The adrianichthyid Horaichthys from India, uniquely among atherinomorphs, produces encapsulated sperm bundles, or spermatophores. In adrianichthyids other than Oryzias, fertilization is apparently internal. The eggs of many species of adrianichthyids are retained externally by the female for various lengths of time. Females of the species Xenopoecilus oophorus, known as the egg-carrying buntingi, carry a cluster of about 30 fertilized eggs attached by filaments in an external concavity near the vent. The pelvic fins cover and protect this egg mass.

Conservation status

No Beloniformes are CITES listed, or listed as endangered by the U. S. Fish and Wildlife Service. However, 16 species are included on the IUCN Red List. Eight of those, mostly Oryzias species, are categorized as Vulnerable, one species is listed as Lower Risk/Near Threatened, and two species are listed as Data Deficient. Three species are listed as Endangered: Oryzias orthognathus, Xenopoecilus oophorus, and Xenopoecilus sarasinorum. Listed as Critically Endangered are Adrianichthys kruyti and Xenopoecilus poptae, both of which are known only from Lake Poso, Sulawesi. Although no Beloniformes are formally listed as Extinct in the Wild by the U. S. Fish and Wildlife Service or Extinct by the IUCN, Adrianichthys kruyti is generally thought to be extinct. Pressure from an introduced species of catfish, in addition to parasites that entered the lake with the catfish, are implicated in the decline of the Lake Poso adrianichthyids.

Significance to humans

Many Beloniformes are fished at night using lights, and some rather creative methods have been devised. Where flyingfishes are abundant, fishermen that leave a light suspended all night over a canoe partially filled with water can return in the morning to a boat full of fresh fish. The fish are drawn to the light and jump into the canoe, but have too little water to jump back out. Flyingfishes are also attracted to leaves or straw scattered about the surface as a place to lay their eggs, and can be fished by using such material.

Some Beloniformes are used by humans as more than just food. Numerous freshwater species, including halfbeaks, ricefishes, and needlefishes, can be found in the aquarium trade. In Thailand, the halfbeak, Dermogenys pusillus, is bred in captivity so that males, which will engage rivals by locking jaws, can be used as fighting fish. Members of the genus Oryzias are propagated in large numbers in captivity to be used in experimental research.

Finally, it should be mentioned that needlefishes can in rare cases be traumatogenic, causing injury or death by means of impalement. In one such case, a hapless surfer was killed when the snout of a fast-swimming needlefish went through his eye socket and into his brain.

Species accounts

List of Species

Japanese rice fish

Oryzias latipes

family

Adrianichthyidae

taxonomy

Poecilia latipes Temminck and Schlegel, 1846, Japan.

other common names

English: Japanese medaka, tooth-carp; German: Japan-Reiskärpfling; Cantonese: Fut mei dzeung ue; Japanese: Medaka.

physical characteristics

Maximum length 1.6 in (4 cm). Small and shallow bodied, with upturned mouth and silvery olive coloration. No spines in dorsal or anal fins. Many strains of captive-raised Japanese rice fish have been selectively bred for pale yellow color. Strains that appear red or mottled black and gold have also been developed.

distribution

Japan, Korea, China, and Vietnam, as well as the great rivers of Southeast Asia: the Mekong, Red, Irrawaddy, and Salween.

habitat

Calm stretches of streams, rice paddies, and wetlands.

behavior

Forms schools, generally peaceful.

feeding ecology and diet

Feeds on zooplankton and insects, as well as some detritus and plant material.

reproductive biology

Fertilization is external, although the eggs are carried for a short time, stuck to the female's abdomen, prior to deposition. Females can produce broods of 10–40 eggs every two days during the breeding season. Eggs are slightly larger than 0.039 in (1 mm) in diameter and usually hatch in 8–14 days.

conservation status

Not threatened.

significance to humans

Used widely in experimental research, also found in the aquarium trade.

Duckbilled buntingi

Adrianichthys kruyti

family

Adrianichthyidae

taxonomy

Adrianichthys kruyti Weber, 1913, Lake Poso, Sulawesi, Indonesia.

other common names

English: Duckbill Poso minnow; German: Entenschnabelkärpfling.

physical characteristics

Maximum length about 4.3 in (11 cm). Large, horizontal, duck-bill shaped mouth, with upper jaw overhanging lower; eyes large, extend beyond dorsal head-profile when viewed from side. Elongate, somewhat compressed.

distribution

Lake Poso, Sulawesi.

habitat

Deeper waters of Lake Poso.

behavior

Unknown.

feeding ecology and diet

Unknown.

reproductive biology

Unknown, though one specimen reported to be a hermaphrodite.

conservation status

Listed as Critically Endangered on the IUCN Red List; Harrison and Stiassny (1999) think it possibly extinct.

significance to humans

Kottelat reported that the adrianichthyids he observed were heavily parasitized by copepods; native fisherman say these parasites became a problem when Clarias was introduced into Lake Poso in the early 1980s. Voracious snakeheads have also been introduced into the lake, and may have led to the decline of the endemic fishes. He argues that the duckbilled buntingi may not be extinct, but just no longer abundant enough for fisherman to expend effort and so never observed. Whatever its status, Adrianichthys kruyti is an example of an endemic species important as a fishery declining dramatically following exotic species introductions by humans.

Atlantic saury

Scomberesox saurus saurus

family

Scomberesocidae

taxonomy

Esox saurus Walbaum, 1792, Cornwall and British seas.

other common names

English: Atlantic needlefish; French: Aiguille de mer; German: Echsenhecht; Spanish: Alcrique.

physical characteristics

Maximum length 19.7 in (50 cm). Elongate and needlefish-like, but with toothless jaws and finlets following the dorsal and anal fins.

distribution

Mediterranean, North Atlantic, rarely Iceland, Norway, Denmark.

habitat

Surface waters of the open ocean.

behavior

Schooling fishes that travel long distances through the open ocean. Spawn in warmer waters, migrate to plankton-rich temperate waters to feed. Leap out of the water when pursued by predators.

feeding ecology and diet

Zooplankton and fish larvae.

reproductive biology

External fertilization, eggs scattered in open water.

conservation status

Not threatened.

significance to humans

Said to have delicious flesh, but not abundant enough to support a large fishery.

Californian needlefish

Strongylura exilis

family

Belonidae

taxonomy

Belone exilis Girard, 1854, San Diego, California.

other common names

French: Aiguille de Californie; Spanish: Agujón bravo de California.

physical characteristics

Maximum length 35.8 in (91 cm). Very elongate, with long snout and sharp teeth. Emarginate caudal fin, no dorsal or anal fin spines.

distribution

Coastally from San Francisco to Peru; also in the Galápagos.

habitat

Lagoons, harbors, and coastal areas. Frequents mangroves and enters freshwaters.

behavior

Sometimes schools in large numbers, leaps out of the water when threatened.

feeding ecology and diet

Feeds on small fishes.

reproductive biology

Eggs are attached to floating vegetation by means of long filaments; larvae drift in surface waters. The eggs are approximately 0.14 in (3.5 mm) in diameter and hatch in about two weeks. Larvae are 0.35–0.47 in (9–12 mm) at hatching.

conservation status

Not threatened.

significance to humans

Sold fresh in fish markets. In very rare cases, may cause injury or death by impalement.

Blackbarred halfbeak

Hemiramphus far

family

Hemiramphidae

taxonomy

Esox far Forsskål, 1775, Luhaiya, Yemen, Red Sea.

other common names

English: Blackbarred garfish; French: Aiguillette, demi-bec bagnard.

physical characteristics

Maximum length 17.7 in (45 cm). Lower jaw beaklike and dramatically longer than upper jaw; color is bluish dorsally and silvery on sides, with three to nine vertical bars. Dorsal and anal fins posteriorly situated, lower lobe of caudal fin longer than upper.

distribution

Indo-West Pacific: Red Sea and East Africa to Samoa, from northern Australia and New Caledonia to the Ryukyu Islands. Has entered the eastern Mediterranean through the Suez Canal.

habitat

Marine; near vegetation in coastal areas.

behavior

Forms schools.

feeding ecology and diet

Feeds mostly on sea grasses, in addition to green algae and diatoms.

reproductive biology

Spawns in estuaries.

conservation status

Not threatened.

significance to humans

Commercially fished, said to have good-tasting flesh, sometimes used as bait.

California flyingfish

Cheilopogon pinnatibarbatus californicus

family

Exocoetidae

taxonomy

Exocoetus californicus Cooper, 1863, Santa Catalina Island, California.

other common names

French: Exocet californien; Spanish: Volador de California.

physical characteristics

Maximum length 15 in (38 cm). One of the "four-winged" flyingfishes; both pectoral and pelvic fins are enlarged. Lower lobe of caudal fin is also considerably larger than the upper. Bluish gray dorsally, silver ventrally.

distribution

Oregon to southern Baja California.

habitat

Surface waters of the open ocean.

behavior

Schooling fishes, capable of leaping out of the water and gliding for long distances, possibly as a means of evading predators.

feeding ecology and diet

Zooplankton and small fishes.

reproductive biology

Spawns in the summer months. Eggs are pelagic, and stick to floating seaweed and other debris. The eggs are approximately 0.07 in (1.8 mm) in diameter. Larvae are roughly 0.17 in (4.5 mm) long at hatching.

conservation status

Not threatened.

significance to humans

Occasionally used as bait.

Resources

Books

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Robert Schelly, MA