Hemiramphidae is a family of 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 fishing themselves, these forage fish support artisan fishing and local markets worldwide. They are also fed upon by other commercially important fishes, such as , , and .
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,
Hemiramphus 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, Theodore Nicholas Gill erected Hemiramphidae, deriving its name from
Hemiramphus, the family's
biological type.
The name comes from the
Ancient Greek hemi, meaning half, and
rhamphos, meaning beak or bill.
There are currently eight genera (including 60 species) within the family Hemirampphidae:
This family is primarily Marine biology and found in the Atlantic, Pacific, and , though some inhabit estuary and .
Evolution
The halfbeaks'
fossil record extends into the
Palaeogene.
The earliest known halfbeak is "
Hemiramphus"
edwardsi from the
Eocene at
Monte Bolca,
Italy, although its attribution to the extant
Hemiramphus is doubtful.
Apart from differences in the length of the upper and lower jaws,
Holocene and fossil halfbeaks are distinguished by the fusion of the third pair of upper
pharynx 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 , , and sauries.
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 cladistics to the flyingfish family.
Rather than being closely related to the flyingfishes, the subfamily Zenarchopterinae appears to be the sister group of the 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.
Morphology
The halfbeaks are elongate, streamlined fish adapted to living in open water. Halfbeaks can grow to over SL in the case of
Euleptorhamphus. The scales are relatively large, cycloid (smooth), and easily detached. There are no spines in the fins.
A distinguishing characteristic is that the third pair of upper pharyngeal bones are anklylosed (fused) into a plate. Halfbeaks are one of several fish families that lack a
stomach, all of which possess a pharyngeal jaw apparatus (pharyngeal mill).
Most species have an extended lower jaw, at least as juveniles, though this feature may be lost as the fish mature, as with
Chriodorus, for example.
As is typical for surface dwelling, open water fish, most species are silvery, darker above and lighter below, an example of countershading. The tip of the lower jaw is bright red or orange in most species.
Halfbeaks carry several adaptations to feeding at the water surface. The eyes and nostrils are at the top of the head and the upper jaw is mobile, but not the lower jaw. Combined with their streamlined shape and the concentration of fins towards the back (similar to that of a Esox), these adaptations allow halfbeaks to locate, catch, and swallow food items very effectively.
Range and habitat
Halfbeaks inhabit warm seas, predominantly at the surface, in the
Atlantic,
Indian Ocean, and
Pacific oceans.
A small number are found in
estuary. Most species of marine halfbeaks are known from continental coastlines, but some extend into the western and central
Pacific, and one species (
Hyporhamphus ihi) is
endemism to
New Zealand.
is a worldwide marine genus.
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]
Ecology and behavior
Feeding
Marine halfbeaks are feeding on algae; marine plants such as ; plankton; invertebrates such as Sea butterfly and crustaceans; and smaller fishes.
Behavior
Marine halfbeaks are typically pelagic schooling forage fish.
Some marine halfbeaks, including Euleptorhamphus velox and Euleptorhamphus viridis, are known for their ability to jump out of the water and glide over the surface for considerable distances, and have consequently sometimes been called flying halfbeaks.
Reproduction
Hemiramphidae species are all external fertilizers.
Relatively little is known about the ecology of juvenile marine halfbeaks, though estuarine habitats seem to be favored by at least some species.
Relationship to humans
Halfbeak fisheries
Halfbeaks are not a major target for Fishing, though small fisheries for them exist in some places, for example in South Australia where fisheries target the southern sea garfish ( Hyporhamphus melanochir).
In some localities significant exist to supply Game fish.
See also
-
USS Halfbeak (SS-352) American submarine named after these fish
