#garpikes

Usually they are described as 'living fossils' and as not having evolved very much - as though they were relictual. Rather the pressures of natural selection have stabilised these creatures, as rather perfect at what they do. The same applies to other ancient animals such as horseshoe crabs, tadpole shrimp, and lungfishes. As opposed to so-called living fossils that have no ancient, similar fossil relatives - such as the echidna; or that differ in important ways from what is known or sometimes assumed about their ancestors - such as the tuatara, the coelacanth, and the vampire squid; and those that are completely modern, such as the Komodo dragon.

The name 'garfish' is derived from an old, Germanic word meaning a spear, and it first applied to an unrelated needlefish, Belone. It is customary to refer to lepisosteids as 'garpikes' to distinguish them from their namesake; but of course, they are not related to the true pikes or esocids, either. Nor are they close allies of the pine characins, the ctenolucids, that are often called gars and appear in the aquarium yrade. All of the belonids, the ctenolucids, and the esocids belong to the main clade or 'family' of fishes, called the teleosts or true finfishes. The gar(pike) clade is related to the teleosts, but their last common ancestry with them is ancient indeed, and garpikes retain traits inferable for ancestral teleosts.

Garpikes are visually striking for their dense scales, which have a different composition from those of typical fishes; the latter have ledd hardened scales. One primitive trait of garfishes is that they can breathe air, although they are obligatorily aquatic. This is because the swim bladder of typical fishes - which is now used as their flotation device - is evolved from a lung, and not the other way around. Unlike gouramis, for example, the garpikes never had to invent a way to breathe air again, because they had never lost their ancestral ability to do so. Another ancient trait of the garpikes is that their tails are vertically asymmetrical. Although not to the same degree as in sharks, their vertebral column extends into the upper portion of their tail fin. Thus they have 'heterocercal' tails, unlike the 'homocercal' tails of most fishes.

Zoologists have traditionally considered garpikes to be members of a grouping named holosteans, that was considered, along with the bowfin, as a sort of primitive grade ancestral to the ordinary fishes, which are called teleosts. For decades zoologists have debated wether the bowfin is closer to the teleosts or to the garpikes; the name of Holostei refers only to the hypothesis that garpikes and bowfins are closely related. All the three clades together comprise the neopterygians, which are the only fishes in the original Pisces. (But the garpikes were misassigned as members of a teleost genus!)

Ancient members of the garfish group occupied broader niches during the Mesozoic, including well known shellfish crushers with deep bodies. Because of their bony scales, these fish are well known from he dorts of fossil beds that yield dinosaurs such as Iguanodon. However recognisable, almost modern type garpikes first appeared in the later Jurassic, and coeval with giant sauropod dinosaurs, plated stegosaurs, fierce allosaurs: flying pterodactyls; marine plesiosaurs and ichthyosaurs; and the once astonishing Archaeopteryx - which is now no longer the 'first bird', nor the most primitive. But during the same period of time that separates us from Archaeopteryx, the garpikes have changed little - a situation that is known as 'bradytely'.

Nowadays the garpikes have a Nearctic distribution that extends out into the Antillean archipelago; the latter is usually considered to be of a South American character, in most respects. But even during the Cenozoic, the garpikes had a wider distribution; for example they were fossilized in Germany, at the famous Messel Pit locality. It isn't really clear why this clade flourishes in North America, but went extinct on other continents

Garpikes have a similar superficial resemblance to the crocodile family, as they have massive scales, long toothy jaws, and a similar niche of hunting from a lurking position. Compared to true pikes, the garpikes have very rigid bodies, and this helps them to 'pass' for wood. Indeed they show a preference, in the wild, for associating themselves with tangles of wood in shallow water.

There a few species of garpikes and all of them are similar, although of course they differ among themselves in their precise niche, and their potential lengths. They are no longer traded as commonly as they used to be in Europe, and I have even seen small alligator gars offered for sale in the past. But probably the smallest of the living species, is the shortnose gar (Lepisosteus platostomus) from the Mississippi and Missouri river basins.

L. platostomus typically grow to about 60 centimeters to 24 inches long; but the species may grow to nearly half as long again. This is a species from backwaters and flow moving waters, where it waits near the water surface and hunts fish, amphibians, and insects. This species ambushes terrestrial prey from the water surface, and also functions as a scavenger. It is known to consume more amphibian and terrestrial arthropods as prey than other gar species sharing the dame habitat. Gars seize their prey using a sideways swipe of their heads during the lunge forwards, unlike similarly shaped teleosts which strike directly head on.

Shortnose gars inhabit seasonal climates with a cold season, but begin to spawn when the water temperature reaches 16 to 21 degrees centigrade. From this it may be seen that they are fine in what aquarists call a 'coldwater tank'; one that is unheated at a living g room temperature of 18 to 22 degrees. The species naturally experiences summer temperatures, that are equivalent to our 'tropical' tanks. They are unfussy about the water chemistry and can be thought to prefer broadly circumneutral waters. in the aquarium they should be given tangled wood to lurk around, and tall stem plants to hide among.

Garpikes are obligate carnivores that seize upon small fishes and similar prey animals. However, their gape is not extraordinary, and their craniofacial skeleton limits the size of the prey that they can take. Despite the usual folklore surrounding predatory fishes, gars will accept defrosted, meaty foods. And big, deep bodied tankmates should not be at risk; nor should those with diameters wider than that of the gar. Their conical teeth are plainly optimized for snapping at smaller prey,and as they occupy the upper water column they are easily compatible with many other big fishes. The problem is that even though it is a 'small' gar, even L. platostomus requires a large tank indeed, or an indoor pool.