Hemiramphidae is a family of fishes that are commonly called halfbeaks, spipe fish or spipefish. They are a geographically widespread and numerically abundant family of epipelagic fish inhabiting warm waters around the world. The halfbeaks are named for their distinctive jaws, in which the lower jaws are significantly longer than the upper jaws. The similar viviparous halfbeaks (family Zenarchopteridae) have often been included in this family.
Though not commercially important themselves, these forage fish support artisanal fisheries and local markets worldwide. They are also fed upon by other commercially important predatory fishes, such as billfishes, mackerels, and sharks.
Taxonomy
In 1758, Carl Linnaeus was the first to scientifically describe a halfbeak, Esox brasiliensis (now Hemiramphus brasiliensis). In 1775 Peter Forsskål described two more species as Esox, Esox far and Esox marginatus. It was not until 1816 that Georges Cuvier created the genus Hemiramphus; from then on, all three were classified as Hemiramphus. In 1859, Gill erected Hemiramphidae, deriving its name from Hemiramphus, the family's type genus. The name comes from the Greek hemi, meaning half, and rhamphos, meaning beak or bill.
There are currently eight genera within the family Hemirampphidae:
Arrhamphus Günther, 1866
Chriodorus Goode & Bean, 1882
Euleptorhamphus Gill, 1859
Hemiramphus Cuvier, 1816
Hyporhamphus Gill, 1859
Melapedalion Fowler, 1934
Oxyporhamphus Gill, 1864
Rhynchorhamphus Fowler, 1928
This family is primarily marine and found in the Atlantic, Pacific, and Indian Oceans, though some inhabit estuaries and rivers.
Evolution
The halfbeaks' fossil record extends into the Lower Tertiary. The earliest known halfbeak is “Hemiramphus” edwardsi from the Eocene at Monte Bolca, Italy. Apart from differences in the length of the upper and lower jaws, recent and fossil halfbeaks are distinguished by the fusion of the third pair of upper pharyngeal bones into a plate.
Phylogeny
The phylogeny of the halfbeaks is in a state of flux.
On the one hand, there is little question that they are most closely related to three other families of streamlined, surface water fishes: the flyingfishes, needlefishes, and sauries. Traditionally, these four families have been taken to together comprise the order Beloniformes. The halfbeaks and flyingfishes are considered to form one group, the superfamily Exocoetoidea, and the needlefishes and sauries another, the superfamily Scomberesocoidea.
On the other hand, recent studies have demonstrated that rather than forming a single monophyletic group (a clade), the halfbeak family actually includes a number of lineages ancestral to the flyingfishes and the needlefishes. In other words, as traditionally defined, the halfbeak family is paraphyletic.
Within the subfamily Hemiramphinae, the "flying halfbeak" genus Oxyporhamphus has proved to be particularly problematic; while morphologically closer to the flyingfishes, molecular evidence places it with Hemiramphus and Euleptorhamphus. Together, these three genera form the sister group to the flyingfish family. The other two hemiramphine genera Hyporhamphus and Arrhamphus form another clade of less clear placement.
Rather than being closely related to the flyingfishes, the subfamily Zenarchopterinae appears to be the sister group of the needlefishes and sauries. This is based on the pharyngeal jaw apparatus, sperm ultrastructure, and molecular evidence. However, this hypothesis has awkward implications for how the morphological evolution of the group is understood, because the fused pharyngeal plate has been considered reliably diagnostic of the halfbeak family. Furthermore, the existing theory that because juvenile needlefish pass through a developmental stage where the lower jaw is longer than the upper jaw (the so-called "halfbeak stage") the theory that halfbeaks are paedomorphic needlefish is untenable. In fact the unequal lengths of the upper and lower jaws of halfbeaks appears to be the basal condition, with needlefish being relatively derived in comparison.
