Umbridae is a family of fish in the order

Esociformes The Esociformes () are a small order of ray-finned fish, with two families, Umbridae and Esocidae. The pikes of genus '' Esox'' give the order its name. This order is closely related to the Salmoniformes, the two comprising the superorder Prot ...

, which contains pike, pickerel, and mudminnows. The single living genus, ''

Umbra The umbra, penumbra and antumbra are three distinct parts of a shadow, created by any light source after impinging on an opaque object. Assuming no diffraction, for a collimated beam (such as a point source) of light, only the umbra is cast. Th ...

'', occupies weed-choked freshwater habitats in eastern North America and eastern Europe. While the family traditionally contained the genera ''Umbra'', '' Novumbra'', and ''

Dallia ''Dallia'' is a genus of mudminnows native to Russia and Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on ...

'', recent genetic and paleontological research have recovered this grouping as paraphyletic, with ''Novumbra'' and ''Dallia'' being moved to the family

Esocidae Esocidae is a family of fish in the order Esociformes, which contains pike, pickerel, and mudminnows. While the family traditionally only contained the genus ''Esox'', recent genetic and paleontological research have recovered ''Novumbra'' and ' ...

Distribution

Umbridae contains three extant species, all within the genus ''Umbra'': ''Umbra pygmaea'', ''Umbra limi'', and ''Umbra krameri''. ''U. pygmaea'' can be found across the

eastern United States The Eastern United States, commonly referred to as the American East, Eastern America, or simply the East, is the region of the United States to the east of the Mississippi River. In some cases the term may refer to a smaller area or the East C ...

and southeastern

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

. ''U. limi'' ranges throughout the

Great Lakes The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes in the mid-east region of North America that connect to the Atlantic Ocean via the Saint Lawrence River. There are five lakes ...

region and

Mississippi River The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it f ...

basin of

North America 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 Car ...

. ''U. krameri'' can be found in the Danube and Dniester River basins of Europe. ''Umbra ''spp. are most commonly found in the Atlantic coast regions of North America, along the marshy, low-oxygen areas of the

, and in similar environments in

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

. All fossil specimens have been recovered from Europe, occupying similar niches to extant species.

Behavior

Like all esociformes, the extant species of Umbridae are sight-based ambush predators, with umbrids occupying the niche of a bottom-feeding generalist. Diet changes based on seasonal availability, however primarily consists of invertebrates in all extant species. Detritus is also a major stomach content throughout the year as reported in ''U. pygmaea''. During winter months, U. limi has been observed hunting fish. Cannibalism has been observed in at least ''U. pygmaea''. Umbrids, like ''Dallia'' and ''Novumbra'', have an extreme tolerance for hypoxic conditions. ''Umbra'' has been observed surviving under ice in particularly cold winters, and has the ability to survive desiccation by burrowing tail-first into mud in times of drought. ''Umbra'' can breathe atmospheric air using a modified gas bladder to absorb oxygen.

Relationships

Umbrids have been present in Europe with fossils of the primitive genus '' Boltyshia'' dating back to the Paleocene. Following ''Boltyshia'', fossils of '' Palaeoesox'', another primitive genus, entered the known fossil record in the Middle Eocene. In contrast to ''Boltyshia'', ''Palaeoesox'' had a much longer stratigraphical range, surviving until possibly the Late Miocene based on otoliths assigned to the genus, though at least the Middle Miocene based on the presence of body fossils. ''Palaeoesox'' overlaps its temporal range with ''Umbra''; the two species coexisted within Europe for at least 10 million years, as fossils of the earliest members of the genus ''Umbra'' have been recovered during the latest Oligocene. A single species has been assigned to the genus '' Proumbra'', which was recovered in fossil beds dating to the late Oligocene. Genetic work has reported that separation of the European and North American species in the genus ''Umbra'' occurred roughly at the end of the Late Cretaceous and earliest half of the Paleogene, at the date of 60.57 million years ago with the 95% highest probability density of 39.57-81.75. The cause of the split in the genus coincides with the separation of the European and North American continents. One of the basalmost genera, ''Palaeoesox'', preserves depressible teeth similar to those of ''

Esox ''Esox'' is a genus of freshwater fish commonly known as pike or pickerel. It is the type genus of the family Esocidae. The type species of the genus is ''Esox lucius'', the northern pike. ''Esox'' has been present in Laurentia (which later ...

''. This trait may have been present in the last common ancestor of Esocidae before the umbrid/esocid split, and is lost today in ''Umbra'', ''Dallia'', and ''Novumbra''. The following cladogram illustrates the relationship between umbrid genera.

References

{{Taxonbar, from=Q917598 Ray-finned fish families Esociformes de:Hundsfische