All Topics  
Bullhead shark

 
Bullhead Shark

 
   Email Print
   Bookmark   Link
 

 

Bullhead shark
 
 
  Topics Bullhead shark Topic Home

The bullhead sharks are a small order
Order (biology)

In Biological classification used in biology, the order is a taxonomic rank between class and family . The superorder is a rank between class and order....
 (Heterodontiformes) of basal (primitive) modern shark
Shark

Sharks are a type of fish with a full Cartilage skeleton and a highly Streamlines, streaklines and pathlinesd body. They respire with the use of five to seven gill slits....
s (Neoselachii
Neoselachii

Neoselachii are a subclass of class Chondrichthyes. It contains two kinds of fishes: sharks and rays. The other subclass is Holocephali....
). There are nine living species in a single genus, Heterodontus, in the family Heterodontidae. All are relatively small, with the largest species being just in adult length. They are bottom feeders in tropical and subtropical waters.

The Heterodontiforms appear in the fossil record in the Early Jurassic
Jurassic

The Jurassic is a geologic period that extends from about annum to  Ma, that is, from the end of the Triassic to the beginning of the Cretaceous....
, well before any of the other Galeomorphii, a group which includes all modern sharks except the dogfish
Dogfish

Dogfish is a name applied to a number of small sharks found in the northeast Atlantic Ocean, Pacific Ocean, and Mediterranean Sea oceans. It is applied especially to those in the three Family Scyliorhinidae, Dalatiidae, and Squalidae....
 and its relatives.






Discussion
Ask a question about 'Bullhead shark'
Start a new discussion about 'Bullhead shark'
Answer questions from other users
Full Discussion Forum



Encyclopedia


The bullhead sharks are a small order
Order (biology)

In Biological classification used in biology, the order is a taxonomic rank between class and family . The superorder is a rank between class and order....
 (Heterodontiformes) of basal (primitive) modern shark
Shark

Sharks are a type of fish with a full Cartilage skeleton and a highly Streamlines, streaklines and pathlinesd body. They respire with the use of five to seven gill slits....
s (Neoselachii
Neoselachii

Neoselachii are a subclass of class Chondrichthyes. It contains two kinds of fishes: sharks and rays. The other subclass is Holocephali....
). There are nine living species in a single genus, Heterodontus, in the family Heterodontidae. All are relatively small, with the largest species being just in adult length. They are bottom feeders in tropical and subtropical waters.

The Heterodontiforms appear in the fossil record in the Early Jurassic
Jurassic

The Jurassic is a geologic period that extends from about annum to  Ma, that is, from the end of the Triassic to the beginning of the Cretaceous....
, well before any of the other Galeomorphii, a group which includes all modern sharks except the dogfish
Dogfish

Dogfish is a name applied to a number of small sharks found in the northeast Atlantic Ocean, Pacific Ocean, and Mediterranean Sea oceans. It is applied especially to those in the three Family Scyliorhinidae, Dalatiidae, and Squalidae....
 and its relatives. However, they have never been common, and it is likely their origin lies even further back.

Description

The Heterodontiforms are morphologically rather distinctive. The mouth is located entirely anterior to the orbits. Labial cartilages are found in the most anterior part of the mouth. Nasoral grooves are present, connecting the external nares to the mouth. The nasal capsules are "trumpet-shaped" & well-separated from orbits. Circumnarial skin fold
Skin fold

Skin folds are areas of skin where it folds. Many skin folds are distinct, heritable anatomical features, and may be used for identification of animal species, while others are non-specific and may be produced either by individual development of an organism or by arbitrary application of force to skin, either by the actions of the muscles of...
s present; but the rostral process of neurocranium (braincase) absent, although a precerebral fossa is present. Finally, the braincase bears a supraorbital crest.

The eyes lack a nictitating membrane
Nictitating membrane

The nictitating membrane is a transparent or translucent third eyelid present in some animals that can be drawn across the eye for protection and to moisten the eye while also keeping visibility....
. A spiracle
Spiracle

Spiracles are small openings on the surface of some animals that usually lead to respiratory systems.In elasmobranchs , a spiracle is found behind each eye, and is often used to pump water through the gills while the animal is at rest ....
 is present, but small. The dorsal
Dorsum (biology)

In anatomy, the dorsum is the upper side of animals that typically run, fly, or swim in a horizontal position, and the back side of animals that walk upright....
 ends of branchial arches 4 and 5 are attached, but not fused into a "pickaxe" as in lamniform sharks
Lamniformes

Lamniformes is an order of sharks, also known as mackerel sharks . It includes some of the most familiar species of sharks, such as the great white shark, and some extremely rare types, such as the megamouth shark....
. Heterodontiforms have 2 dorsal fin
Dorsal fin

A wikt:dorsal fin is a fin located on the backs of some fish, whales, dolphins, and porpoises, as well as the ichthyosaurs. Its main purpose is to stabilize the animal against rolling and assist in sudden turns....
s, with fin spines, as well as an anal fin. The dorsal and anal fin also contain basal cartilage
Cartilage

Cartilage is a type of dense connective tissue. It is composed of specialized cells called chondrocyte that produce a large amount of extracellular matrix composed of collagen fibers, abundant ground substance rich in proteoglycan, and elastin fibers....
s, not just fin rays.

Species

There are nine living species of bullhead shark:
  • Horn shark
    Horn shark

    The horn shark, Heterodontus francisci, is a bullhead shark. It can reach a size of 121 cm and weigh 10 kilogram . It is brown with black spots....
    , Heterodontus francisci (Girard, 1855)
  • Crested bullhead shark
    Crested bullhead shark

    The crested bullhead shark, Heterodontus galeatus, is a bullhead shark of the family Heterodontidae, found in the western Pacific Ocean on the continental shelf around eastern Australia from the surface to 90 m....
    , Heterodontus galeatus (Günther, 1870)
  • Japanese bullhead shark
    Japanese bullhead shark

    The Japanese bullhead shark, Heterodontus japonicus, is a bullhead shark of the family Heterodontidae, found in the northwest Pacific Ocean around Japan, Korea, and northern China including Taiwan Island on the continental shelf at depths of between 6 and 37 m....
    , Heterodontus japonicus Maclay & Macleay, 1884
  • Mexican hornshark
    Mexican hornshark

    The Mexican hornshark, Heterodontus mexicanus, is a bullhead shark of the family Heterodontidae, found in the tropical eastern Pacific Ocean from the surface to 50 m....
    , Heterodontus mexicanus Taylor & Castro-Aguirre, 1972
  • Oman bullhead shark
    Oman bullhead shark

    The Oman bullhead shark, Heterodontus omanensis, is a bullhead shark of the family Heterodontidae, found in the tropical western Indian Ocean around central Oman from the surface to 70 m....
    , Heterodontus omanensis Baldwin, 2005
  • Port Jackson shark
    Port Jackson shark

    The Port Jackson shark, Heterodontus portusjacksoni, is a type of bullhead shark shark of the family Heterodontidae, found in the coastal region of southern Australia, including the waters off Port Jackson....
    , Heterodontus portusjacksoni (Meyer, 1793)
  • Galapagos bullhead shark
    Galapagos bullhead shark

    The Galapagos bullhead shark, Heterodontus quoyi, is a bullhead shark of the family Heterodontidae, found in the tropical eastern Pacific Ocean between latitudes Equator to 10th parallel south, at depths of between 3 and 40 m....
    , Heterodontus quoyi (Fréminville, 1840)
  • Whitespotted bullhead shark
    Whitespotted bullhead shark

    The whitespotted bullhead shark, Heterodontus ramalheira, is a bullhead shark of the family Heterodontidae, found in the western Indian Ocean between latitudes 22nd parallel north to 26th parallel south, at depths of between 40 and 275 m....
    , Heterodontus ramalheira (Smith, 1949)
  • Zebra bullhead shark
    Zebra bullhead shark

    The zebra bullhead shark, Heterodontus zebra , is a bullhead shark of the family Heterodontidae, found in the subtropical western Pacific Ocean between latitudes 40th parallel north to 20th parallel south, at depths of between 50 and 200 m....
    , Heterodontus zebra (Gray, 1831)


See also

  • List of prehistoric cartilaginous fish
    List of prehistoric cartilaginous fish

    This list of prehistoric cartilaginous fish is an attempt to create a comprehensive listing of all Genus that have ever been included in the class chondrichthyes and are known from the fossil record....