Galeomorphi is a

superorder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...

shark Sharks are a group of elasmobranch cartilaginous fish characterized by a ribless endoskeleton, dermal denticles, five to seven gill slits on each side, and pectoral fins that are not fused to the head. Modern sharks are classified within the ...

s. They are sometimes called galea or galean sharks. There are about 300 living

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

in 23

families Family (from ) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictability, structure, and safety as ...

. Galean sharks are divided into four

orders Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * H ...

: the Heterodontiformes,

Orectolobiformes Carpet sharks are sharks classified in the order (biology), order Orectolobiformes . Sometimes the common name "carpet shark" (given because many species resemble ornately patterned carpets) is used interchangeably with "wobbegong", which is the ...

Lamniformes The Lamniformes (, from Greek ''lamna'' "fish of prey") are an order (biology), order of sharks commonly known as mackerel sharks (which may also refer specifically to the family Lamnidae). It includes some of the most familiar species of sharks, ...

, and

Carcharhiniformes Carcharhiniformes ( from Classical Greek ' (karcharos) 'sharp/jagged' and ' (rhinos) 'nose', plus Latin ''forme'' 'shape'), commonly known as ground sharks, are the largest order of sharks, with over 270 species. They include a number of common ...

. The extinct, enigmatic Synechodontiformes are presently placed by some authors in the galeomorphs, but their taxonomic position still remains uncertain.

Classification

Order Heterodontiformes

The bullhead sharks are a small

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

of basal modern

s (

Neoselachii Elasmobranchii () is a subclass of Chondrichthyes or cartilaginous fish, including modern sharks ( division Selachii), and batomorphs (division Batomorphi, including rays, skates, and sawfish). Members of this subclass are characterised by h ...

). All are relatively small, with the largest species being just in adult length. They are bottom feeders in tropical and subtropical waters. They appear in the fossil record in the Early

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

, well before any of the other galean sharks. However, they have never been common, and it is likely their origin lies even further back. There are nine living species in a single genus, ''Heterodontus'' and a single family. * Family Heterodontidae (Bullhead sharks)

Order Orectolobiformes

Carpet sharks are another small

of sharks, so called because many members have ornate patterns reminiscent of carpets. Sometimes the term "carpet shark" is used interchangeably with wobbegong, which are a subgroup of the order. Carpet sharks have two

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

s, without spines, and a small mouth that is forward of the eyes. Many have

barbel Barbel may refer to: *Barbel (anatomy), a whisker-like organ near the mouth found in some fish (notably catfish, loaches and cyprinids) and turtles *Barbel (fish), a common name for certain species of fish **''Barbus barbus'', a species of cyprini ...

s and small

gill slit Gill slits are individual openings to gills, i.e., multiple gill arches, which lack a single outer cover. Such gills are characteristic of cartilaginous fish such as sharks and rays, as well as deep-branching vertebrates such as lampreys. In c ...

s, with the fifth slit overlapping the fourth. The upper lobe of the

caudal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only ...

tends to be mostly in line with the body, while the lower lobe is poorly developed. The order has around 43 species in 7 families and 13 genera: * Family Brachaeluridae Applegate (Blind sharks) * Family Ginglymostomatidae

Gill A gill () is a respiration organ, respiratory organ that many aquatic ecosystem, aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow r ...

, 1862 (Nurse sharks) * Family Hemiscylliidae

, 1862 (Bamboo sharks) * Family Orectolobidae

, 1896 (Wobbegong sharks) * Family

Parascylliidae Parascylliidae, or the collared carpet sharks, is a family of sharks in the order Orectolobiformes, which are only found in shallow waters of the western Pacific. The family Parascylliidae contains two genera, '' Cirrhoscyllium'' and '' Parascyl ...

, 1862 (Collared carpet sharks) * Family Rhincodontidae ( J. P. Müller & Henle, 1839) (Whale sharks) * Family Stegostomatidae

, 1862 (Zebra sharks)

Order Lamniformes

Mackerel sharks are an order which includes some of the most familiar species of sharks, such as the

great white shark The great white shark (''Carcharodon carcharias''), also known as the white shark, white pointer, or simply great white, is a species of large Lamniformes, mackerel shark which can be found in the coastal surface waters of all the major ocea ...

, as well as more unusual representatives, such as the

goblin shark The goblin shark (''Mitsukurina owstoni'') is a rare species of deep-sea shark. Sometimes called a "living fossil", it is the only extant representative of the family Mitsukurinidae, a lineage some 125 million years old. This pink-skinned ani ...

and the megamouth shark. Members of the order are distinguished by possessing two

s, an

anal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...

, five gill slits, eyes without

nictitating membrane The nictitating membrane (from Latin '' nictare'', to blink) is a transparent or translucent third eyelid present in some animals that can be drawn across the eye from the medial canthus to protect and moisten it while maintaining vision. Most ...

s, and a mouth extending behind the eyes. Mackerel sharks may also refer specifically to the family

Lamnidae The Lamnidae are the family of mackerel sharks known as white sharks. They are large, fast-swimming predatory fish found in oceans worldwide, though they prefer environments with colder water. The name of the family is formed from the Greek word ...

. The order includes seven families and sixteen living species: * Family

Alopiidae Thresher sharks are large mackerel sharks of the family Alopiidae found in all temperate and tropical oceans of the world; the family contains three extant species, all within the genus ''Alopias''. All three thresher shark species have been ...

Bonaparte, 1838 (Thresher sharks) * Family Carchariidae

Müller Müller may refer to: Companies * Müller (company), a German multinational dairy company ** Müller Milk & Ingredients, a UK subsidiary of the German company * Müller (store), a German retail chain * GMD Müller, a Swiss aerial lift manufacturi ...

& Henle, 1839 (Sand tiger sharks) * Family

Cetorhinidae Cetorhinidae is a family of filter feeding mackerel sharks, whose members are commonly known as basking sharks. It includes the extant basking shark, ''Cetorhinus'', as well as two extinct genera, '' Caucasochasma'' and ''Keasius ''Keasius'' ...

, 1862 (Basking sharks) * Family

J. P. Müller and Henle, 1838 * Family Megachasmidae

Taylor Taylor, Taylors or Taylor's may refer to: People * Taylor (surname) ** List of people with surname Taylor * Taylor (given name), including Tayla and Taylah * Taylor sept, a branch of Scottish clan Cameron * Justice Taylor (disambiguation) ...

, Compagno & Struhsaker, 1983 (Megamouth shark) * Family Mitsukurinidae D. S. Jordan, 1898 * Family Odontaspididae

& Henle, 1839 (Sand sharks) * Family Pseudocarchariidae Compagno, 1973 (Crocodile shark) * Family Cretoxyrhinidae (Extinct) * Family

Otodontidae Otodontidae is an extinct family of sharks belonging to the order Lamniformes. Its members have been described as megatoothed sharks. They lived from the Early Cretaceous to the Pliocene, and included genera such as '' Otodus,'' including the gi ...

(Extinct)

Order Carcharhiniformes

Ground sharks are the largest order of sharks, and include a number of common types such as the blue shark, catsharks, swellsharks and

sandbar shark The sandbar shark (''Carcharhinus plumbeus''), also known as the brown shark or thickskin shark, is a species of requiem shark, and part of the family Carcharhinidae, native to the Atlantic Ocean and the Indo-Pacific. It is distinguishable by i ...

s. Members of the orders are characterized by the presence of a

over the eye, two

s, an

, and five

gill A gill () is a respiration organ, respiratory organ that many aquatic ecosystem, aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow r ...

slits. The families in the order Carcharhiniformes are expected to be revised; recent

DNA Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...

studies show that some of the traditional groups are not

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

. The order includes eight families and over 270 species: * Family Carcharhinidae (Requiem sharks) * Family Hemigaleidae (Weasel sharks) * Family Leptochariidae (Barbeled houndshark) * Family

Proscylliidae The finback catsharks are a small family (biology), family, the Proscylliidae, of Carcharhiniformes, ground sharks. They can be found in warm seas worldwide and are often the most numerous and common shark in tropical regions. They are generally ...

(Finback catsharks) * Family Pseudotriakidae (False catsharks) * Family

Scyliorhinidae Scyliorhinidae is a Family (biology), family of sharks, one of a few families whose members share the common name catsharks, belonging to the Order (biology), order Carcharhiniformes, the ground sharks. Although they are generally known as cats ...

(Catsharks) * Family Sphyrnidae (Hammerhead sharks) * Family Triakidae (Houndsharks)

References

External links

* . Database of bibliography of living/fossil sharks and rays (Chondrichtyes: Selachii) with more than 15.000 listed papers and many download links. {{Taxonbar, from=Q47969 Elasmobranchii Chordate superorders