''Nigronia serricornis'' has many

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...

s including hellgrammites or fishflies or saw-combed fishflies. The genus ''Nigronia'' has one other

North American North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Ca ...

member ''N. fasciatus'' and South American which lives in much of the same

territory A territory is an area of land, sea, or space, particularly belonging or connected to a country, person, or animal. In international politics, a territory is usually either the total area from which a state may extract power resources or a ...

and is quite similar in all regards. They are holometabolous insects with an aquatic

larval A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The l ...

stage. ''N. serricornis'' is a common inhabitant of woodland streams in North America and they are often the largest insect

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

found in 2nd and 3rd order streams. The larvae are a sit-and -wait ambush predators that feed on a large variety of

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

s. Studies have shown that ''N. serricornis'' has a varying diet throughout the seasons.

Distribution

Despite this small organism's limited ability to disperse it has managed to spread throughout the Eastern United States. The range of ''N. serricornis'' expands northward from

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...

into

Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...

, and west to the US Rocky Mountains. By using

genetic analyses Genetic analysis is the overall process of studying and researching in fields of science that involve genetics and molecular biology. There are a number of applications that are developed from this research, and these are also considered parts of ...

, Heilveil and Berlocher (2006) have identified that there are six major

clades A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, t ...

of ''N. serricornis''. The ancestral

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

in the north end of their range, represent the initial colonization of ''N. serricornis'' on the Eastern US. This

was separated from the derived

by the

Appalachian Mountains The Appalachian Mountains, often called the Appalachians, (french: Appalaches), are a system of mountains in eastern to northeastern North America. The Appalachians first formed roughly 480 million years ago during the Ordovician Period. They ...

Diet

''N. serricomis'' is an active predator and has a varied diet consisting of many smaller invertebrates such as

midges A midge is any small fly, including species in several families of non-mosquito Nematoceran Diptera. Midges are found (seasonally or otherwise) on practically every land area outside permanently arid deserts and the frigid zones. Some midg ...

, caddisflies,

black flies A black fly or blackfly (sometimes called a buffalo gnat, turkey gnat, or white socks) is any member of the family Simuliidae of the Culicomorpha infraorder. It is related to the Ceratopogonidae, Chironomidae, and Thaumaleidae. Over 2,200 speci ...

mayflies Mayflies (also known as shadflies or fishflies in Canada and the upper Midwestern United States, as Canadian soldiers in the American Great Lakes region, and as up-winged flies in the United Kingdom) are aquatic insects belonging to the orde ...

ostracods Ostracods, or ostracodes, are a class of the Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 70,000 species (only 13,000 of which are extant) have been identified, grouped into several orders. They are small crustaceans, typical ...

, and small

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...

s. Studies have shown that ''N. serricomis'' changes its diet from season to season and even from month to month. ''N. serricomis'' larvae feed by foraging with their mandibles open and quickly closing them upon contact with prey.

Development

''N. serricornis'' likely has a three-year life cycle consisting of an

egg An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the a ...

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

pupa A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their ...

and

adult An adult is a human or other animal that has reached full growth. In human context, the term ''adult'' has meanings associated with social and legal concepts. In contrast to a " minor", a legal adult is a person who has attained the age of major ...

stages. The larvae live for up to three years in aquatic environments hunting

s and are the only life stage which feeds. The

then crawls out of the water onto rotting logs or near the shore to pupate in shallow chambers for up to three weeks. After the adults emerge from the chambers they need up to an hour to dry before they can fly away and find mates, although they are relatively poor fliers so they do not move very far from their pupation site. The adults only live for about a week and in this time they need to mate and the female needs to find a site to deposit her eggs, known as an oviposition. The female chooses a site for depositing her eggs on structures that overhang water, such as

leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...

bridge A bridge is a structure built to span a physical obstacle (such as a body of water, valley, road, or rail) without blocking the way underneath. It is constructed for the purpose of providing passage over the obstacle, which is usually somethi ...

s, which allow the newly hatching larva to fall directly into the water and as such the adults to not have to invest any further resources to their

offspring In biology, offspring are the young creation of living organisms, produced either by a single organism or, in the case of sexual reproduction, two organisms. Collective offspring may be known as a brood or progeny in a more general way. This ca ...

. The females seem to choose their oviposition on locations that are unoccupied by other egg masses but otherwise the sites are not limited to any preference for egg deposit.

Oxygen consumption

Most

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...

s, especially aquatic

s, have shown to have fluctuation in their oxygen consumption due to the weight and size of the organism, the

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...

and/or chemistry of the water or the season of the year it is. Year round presence of ''N. serricomis'' larvae in streams results in generally stable respiratory responses to temperature.

Physiologically Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...

, ''N. serricomis'' larvae are adapted to maintain a constant oxygen consumption regardless of temperature, season or stage of larval development. This consistency allows ''N. serricomis'' larvae to vary their

metabolism Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...

in direct relation to its surrounding water temperature.

Interactions with other organisms

''Nigronia serricomis'' larvae, being

s, have to compete with other predators in their streams. This has been observed in Michigan between ''N. serricornis'' and '' Corydalus cornutus''. This

interspecific competition Interspecific competition, in ecology, is a form of competition in which individuals of ''different'' species compete for the same resources in an ecosystem (e.g. food or living space). This can be contrasted with mutualism, a type of symbiosis. ...

affects the ''N. serricornis'' very little due to their generalized diet but when the two do interact '' Corydalus cornutus'' dominates. One interesting interaction ''N. serricornis'' has is with a small

ectoparasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

, ''Nanocladius rectinervis''. This tiny animal lives in a silk tube attached to its

host A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County People *Jim Host (born 1937), American businessman * Michel Host ...

, usually on the mesothorax, and feeds on the detrital material that its host does not fully consume and gets caught up in body folds. They also gain the added stability, protection and mobility by choosing to attach to a mobile predator which has behavioural and morphological adaptions to live in strong currents.

References

{{Taxonbar, from=Q2556100 Corydalidae Insects of North America