Hemigaleidae
Encyclopedia
The weasel sharks are a family, Hemigaleidae, of ground sharks
found from the eastern Atlantic Ocean
to the continental Indo-Pacific
. They are found in shallow coastal waters to a depth of 100 m (330 ft).
Most species are small, reaching no more than 1.4 m long (4.6 ft), though the snaggletooth shark
(Hemipristis elongatus) may reach 2.4 m (7.9 ft). They have horizontally oval eyes, small spiracle
s, and precaudal pits. There are two dorsal fin
s with the base of the first placed well forward of the pelvic fins. The caudal fin has a strong ventral lobe and undulations on the dorsal lobe margin. They feed on a variety of small bony fishes and invertebrate
s; at least two species specialize on cephalopod
s. They are not known to have attacked people.
s are very long, the snout
is wedge-shaped, and the fins are not falchate. Known fossil species include C. affinis
.
. It is distinguished by a rounded snout and very long gill slits. The mouth is long with toothless spaces at the midlines; the lower teeth have very long, strongly hooked cusps and protrude when the mouth is closed. The fins are strongly falchate. Dirrhizodon Kunzinger, 1871 and Heterogaleus Gohar & Mazhar, 1964 are junior synonyms of this genus. Several fossil species are known, including H. curvatus
and H. serra
; in the Tertiary
this genus had a global distribution.
Carcharhiniformes
The ground sharks, order Carcharhiniformes, are the largest order of sharks. With over 270 species, carcharhiniforms include a number of common types, such as the blue shark, catsharks, swellsharks, and sandbar shark....
found from the eastern Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
to the continental Indo-Pacific
Indo-Pacific
The Indo-Pacific is a biogeographic region of the Earth's seas, comprising the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the seas connecting the two in the general area of Indonesia...
. They are found in shallow coastal waters to a depth of 100 m (330 ft).
Most species are small, reaching no more than 1.4 m long (4.6 ft), though the snaggletooth shark
Snaggletooth shark
The snaggletooth shark, Hemipristis elongatus, is a species of weasel shark, family Hemigaleidae, and the only extant member of the genus Hemipristis. It is found in the Indo-West Pacific, including the Red Sea, from southeast Africa to the Philippines, north to China, and south to Australia, at...
(Hemipristis elongatus) may reach 2.4 m (7.9 ft). They have horizontally oval eyes, small spiracle
Spiracle
Spiracles are openings on the surface of some animals that usually lead to respiratory systems.-Vertebrates:The spiracle is a small hole behind each eye that opens to the mouth in some fishes. In the primitive jawless fish the first gill opening immediately behind the mouth is essentially similar...
s, and precaudal pits. There are two dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
s with the base of the first placed well forward of the pelvic fins. The caudal fin has a strong ventral lobe and undulations on the dorsal lobe margin. They feed on a variety of small bony fishes and invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s; at least two species specialize on cephalopod
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda . These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot...
s. They are not known to have attacked people.
Genera and species
There are 8 known species in this family, placed in 4 genera. Hemipristis is placed in the subfamily Hemipristinae, while Chaenogaleus, Hemigaleus, and Paragaleus are placed in the subfamily Hemigaleinae.Chaenogaleus
This genus consists of a single species, the hooktooth shark, characterized by long, hooked teeth in the lower jaw and no toothless spaces at the midlines of the jaws. The gill slitGill 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, rays, sawfish, and guitarfish. Most of these have five pairs, but a few species have 6 or 7 pairs...
s are very long, the snout
Snout
The snout, or muzzle, is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw.-Terminology:The term "muzzle", used as a noun, can be ambiguous...
is wedge-shaped, and the fins are not falchate. Known fossil species include C. affinis
Chaenogaleus affinis
Chaenogaleus affinis is an extinct species of weasel shark which existed during the Miocene period. It was described by Probst in 1879....
.
- Chaenogaleus macrostoma (BleekerPieter BleekerPieter Bleeker was a Dutch medical doctor and ichthyologist, famous for his work on the fishes of East Asia – Atlas Ichthyologique des Orientales Neerlandaises – which was published 1862–1877....
, 1852) (Hooktooth shark)
Hemigaleus
This genus is characterized by a rounded snout and short gill slits. The mouth is short and broadly arched; the teeth have very short cusps, without toothless spaces at the jaw midlines. The dorsal and pelvic fins, and the lower caudal lobe are strongly falchate. At one time or another, this genus has encompassed up to nine species, but most were eventually split off into other genera. Neogaleus Whitley, 1931 is a junior synonym of this genus.- Hemigaleus australiensis W. T. White, Last & Compagno, 2005 (Australian weasel shark)
- Hemigaleus microstoma BleekerPieter BleekerPieter Bleeker was a Dutch medical doctor and ichthyologist, famous for his work on the fishes of East Asia – Atlas Ichthyologique des Orientales Neerlandaises – which was published 1862–1877....
, 1852 (Sicklefin weasel shark)
Hemipristis
This genus contains a single extant species, the snaggletooth sharkSnaggletooth shark
The snaggletooth shark, Hemipristis elongatus, is a species of weasel shark, family Hemigaleidae, and the only extant member of the genus Hemipristis. It is found in the Indo-West Pacific, including the Red Sea, from southeast Africa to the Philippines, north to China, and south to Australia, at...
. It is distinguished by a rounded snout and very long gill slits. The mouth is long with toothless spaces at the midlines; the lower teeth have very long, strongly hooked cusps and protrude when the mouth is closed. The fins are strongly falchate. Dirrhizodon Kunzinger, 1871 and Heterogaleus Gohar & Mazhar, 1964 are junior synonyms of this genus. Several fossil species are known, including H. curvatus
Hemipristis curvatus
Hemipristis curvatus is an extinct species of weasel shark which existed during the Eocene period. It was described by Dames in 1883....
and H. serra
Hemipristis serra
Hemipristis serra is an extinct species of weasel shark which existed during the Miocene period. It was described by Agassiz in 1843....
; in the Tertiary
Tertiary
The Tertiary is a deprecated term for a geologic period 65 million to 2.6 million years ago. The Tertiary covered the time span between the superseded Secondary period and the Quaternary...
this genus had a global distribution.
Paragaleus
This genus has a rounded or slightly pointed snout, short gill slits, and a broadly arched mouth. The upper teeth have long cusps, and there are no toothless spaces at the jaw midlines. The dorsal and pelvic fins and the lower caudal lobe are not falchate in shape. Known fossil species include P. pulchellus and P. antunesi.- Paragaleus leucolomatus Compagno & Smale, 1985 (Whitetip weasel shark)
- Paragaleus pectoralis (Garman, 1906) (Atlantic weasel shark)
- Paragaleus randalli Compagno, Krupp & K. E. CarpenterKent E. CarpenterDr. Kent E. Carpenter is a professor of biological sciences at Old Dominion University, in Norfolk, Virginia who is notable for having two fish species named in his honor, Paracheilinus carpenteri Randall and Lubbock 1981, popularly known as "Carpenter's Flasher Wrasse", and Meganthias carpenteri...
, 1996 (Slender weasel shark) - Paragaleus tengi (J. S. T. F. Chen, 1963) (Straight-tooth weasel shark)