Galeomorphi is a superorder of . They are sometimes called galea or galean sharks. There are about 300 living species in 23 families. Galean sharks are divided into four orders: the Heterodontiformes, Orectolobiformes, Lamniformes, and Carcharhiniformes. 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 of basal modern
(
Neoselachii). 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, 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.
Order Orectolobiformes
Carpet sharks are another small order 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
, without spines, and a small mouth that is forward of the eyes. Many have barbels and small
, with the fifth slit overlapping the fourth. The upper lobe of the
caudal fin 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:
Order Lamniformes
Mackerel sharks are an order which includes some of the most familiar species of sharks, such as the great white shark, as well as more unusual representatives, such as the
goblin shark and the
megamouth shark. Members of the order are distinguished by possessing two
, an
anal fin, five
gill, eyes without nictitating membranes, and a mouth extending behind the eyes. Mackerel sharks may also refer specifically to the family
Lamnidae.
The order includes seven families and sixteen living species:
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
. Members of the orders are characterized by the presence of a nictitating membrane over the eye, two
, an
anal fin, and five
gill slits. The families in the order Carcharhiniformes are expected to be revised; recent
DNA studies show that some of the traditional groups are not
monophyletic.
The order includes eight families and over 270 species:
External links
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. Database of bibliography of living/fossil sharks and rays (Chondrichtyes: Selachii) with more than 15.000 listed papers and many download links.
