The study of systematics is really the elucidation of the evolutionary links that connect species, living and extinct, and provision to each of these species a unique Latinized name according to a well-established set of criteria and rules. These names are standardized so that no matter where in the world one travels, the systematic ('Latin' or 'scientific') name of a particular species is uniquely applicable.

Most specific names have two parts: the genus followed by the species. A minor digression: the generic name is always capitalized and the species epithet is always lower-case — many television and magazine pieces get this wrong and it irritates the Linnaeus out of you if you know and abide by the rules (e.g., it's Homo sapiens, not Homo Sapiens or homo sapiens). The genus is the larger of the two groupings, and may include several species. Species are usually defined as populations of animals that are reproductively isolated from other populations (i.e., they can not breed beyond their own population), though there are enough exceptions that one might adopt a less formal definition such as "a species is a group that someone who studies systematics has said is different from other groups." Works for me. New techniques in genetics allow detection of minute differences between types of animals, but still basically leaves unresolved the rather challenging question: "what exactly is a species?"

Regardless of deeper questions regarding the biological relevance and application of the species concept, the necessity of the binomial nomenclature system by which we may classify flora and fauna, developed by the scientist Carolus Linnaeus, is illustrated by the plethora of local and regional names that exist for many, especially cosmopolitan, species. The great barracuda, occurring in seas throughout the world, is one such species. In Papua New Guinea, for example, the great barracuda is commonly called oda or, more often, malisa (there are something like 740 distinct languages in PNG, so there may well be an abundance of more local names for the beast). Although malisa is a lovely name for the great barracuda — and really gets away from its more macho image prevalent elsewhere in the world — it's also the descriptor applied generically to any of the several species found around PNG.

Animals can recognize those of its own species and those of another species among different species, making the species level of organization a biologically relevant concept; a 'real' phenomenon that exists in nature. Higher levels of organization, such as family and order, represent postulated groupings of animals based upon theorized relatedness. It is here that things can get a bit fuzzy, as many animals do not necessarily recognize others at any level above that of the species. The fact that all they really need to know is to breed with those of their own species (and not of any other) would make any distinction other than 'my species' and 'not my species' unnecessary.

Inevitably, the hierarchy of taxonomic groups can be quite arbitrary and exist as artificial patterns imposed by us upon what might be a complex evolutionary history. They exist solely to enable us to deal with the incredible diversity of animal and plant life that surrounds us. As a rule, humans seem to like categorizing things and scientists are no exception. As a result, the field of systematics can be a contentious one, and existing classification schemes are continually being revised.

Depending upon which authority you believe, the family Sphyraenidae includes between 18 and 20 barracuda species. All sphyraenids (meaning animals that belong to the family Sphyraenidae) are predators on other fishes, are members of the genus Sphyraena, and look quite similar. Fossil members of the family have been found in rocks dating from the Eocene epoch, that were deposited around 50 million years ago.

Until my first trip to Papua New Guinea, where I was able to observe five barracuda species, my research had focused on aspects of the biology, ecology, and behavior of the largest sphyraenid, the great barracuda. Although its taxonomy has been revised many times (in fact, the great barracuda has been given 17 different specific names over the last 250 years), Sphyraena barracuda has stuck as the systematic name of the great barracuda. Sphyraena comes from the Greek word for hammer, in reference to the vague similarity between the shape of the barracuda head and the type of hammer used by geologists. The hammerhead sharks (genus Sphryna) have a similar name from the same Greek root word, referring to the more familiar carpenter hammer shape of their heads. The species epithet barracuda, that makes up the second half of the great barracuda's name, is taken directly from a Caribbean language (original source uncertain). Although sphyraenids are generally referred to as barracudas, the great barracuda is the only species in which the common and systematic names concur. Humans have given the species a confusing myriad of names over the centuries during which they have interacted with it.

Interesting examples of an evolutionary phenomenon known as convergence (where two or more unrelated species show similarities in morphology, life history, or behavior resulting from them experiencing similar environmental pressures) have occurred resulting in fishes that look very much like barracuda. One that I am particularly familiar with is the New Zealand barracouta (Thyrsites atun) that, although very barracuda-like, is properly considered a snake mackerel. It occupies a similar niche to that of barracuda in the coastal waters of New Zealand. Some of the most common fishes in the mesopelagic (mid-water, to a depth of 3.2 km/2 mi) are the barracudinas, small species that have converged on a body plan strikingly similar to the morphology of the great barracuda. Barracudina species include Lestidium atlanticus, that have luminescent organs, and Paralepsis barysoma , the largest — measuring 60 cm in length — that is fed on by tunas. The family Esocidae includes large freshwater predators found in cold-temperate North American and Eurasian inland waters, such as the northern pike (Esox lucius) and muskellunge (E. masquinongy). Pikes and 'muskies' bear more than a passing resemblance to barracudas. Most American and European texts refer to barracudas as 'pike-like' fishes — my marine bias (undoubtedly a direct result of having grown up in the maritime nation of New Zealand) demands that I refer to pikes and other esocids as 'barracuda-like' fishes. It's only right. Regardless, pikes occupy a comparable trophic position in their habitats, where they hunt as a solitary stalking or ambushing top predator. As is often the case with evolutionary convergence, behavioral similarities go hand-in-hand (or fin-in-fin) with morphological commonalities. The fossil lie-in-wait predator Eusthenopteron foordi also shared morphological similarities with barracudas in that its dorsal and ventral fins were placed well back on the body (a trait shared by other lie-in-wait predators, such as gar as well as needlefishes, pike characins, and pike cichlids) and the tail fin had a scalloped appearance.