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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 Division (taxonomy), division Selachii and are the sister group to the Batoidea, Batomorphi (Batoidea, rays and skate (fish), skates). Some sources extend the term "shark" as an informal category including Extinction, extinct members of Chondrichthyes (cartilaginous fish) with a shark-like morphology, such as hybodonts. Shark-like chondrichthyans such as ''Cladoselache'' and ''Doliodus'' first appeared in the Devonian Period (419–359 million years), though some fossilized chondrichthyan-like scales are as old as the Ordovician, Late Ordovician (458–444 million years ago). The earliest confirmed modern sharks (Selachii) are known from the Early Jurassic around , with the oldest known member being ''Agaleus'', though records of true shar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grey Reef Shark
The grey reef shark or gray reef shark (''Carcharhinus amblyrhynchos'', sometimes misspelled ''amblyrhynchus'' or ''amblyrhinchos'') is a species of requiem shark, in the family (biology), family Requiem shark, Carcharhinidae. One of the most common reef sharks in the Indo-Pacific, it is found as far east as Easter Island and as far west as South Africa. This species is most often seen in shallow water near the drop-offs of coral reefs. It has the typical "reef shark" shape, with a broad, round snout and large eyes. It can be distinguished from similar species by the plain or white-tipped first dorsal fin, the dark tips on the other fins, the broad, black rear margin on the caudal fin, tail fin, and the lack of a ridge between the dorsal fins. Most individuals are less than long. The grey reef shark is a fast-swimming, agile predation, predator that feeds primarily on free-swimming bony fishes and cephalopods. Its aggressive demeanor enables it to dominate many other shark specie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pectoral Fin
Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish aquatic locomotion, swim. Apart from the tail or caudal fin, fish fins have no direct connection with the vertebral column, back bone and are supported only by muscles. Fish fins are distinctive anatomical features with varying structures among different clades: in ray-finned fish (Actinopterygii), fins are mainly composed of bone, bony spine (zoology), spines or ray (fish fin anatomy), rays covered by a thin stretch of fish scale, scaleless skin; in lobe-finned fish (Sarcopterygii) such as coelacanths and lungfish, fins are short rays based around a muscular central limb bud, bud supported by appendicular skeleton, jointed bones; in cartilaginous fish (Chondrichthyes) and jawless fish (Agnatha), fins are fleshy "flipper (anatomy), flippers" supported by a cartilaginous skeleton. Fins at different locations of the fish body serve different purposes, and are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dermal Denticle
A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scale (zoology), scales, which can also provide effective Underwater camouflage, camouflage through the use of animal reflectors, reflection and animal coloration, colouration, as well as possible hydrodynamic advantages. The term ''scale'' derives from the Old French , meaning a shell pod or husk. Scales vary enormously in size, shape, structure, and extent, ranging from strong and rigid armour plates in fishes such as shrimpfishes and boxfishes, to microscopic or absent in fishes such as eels and anglerfishes. The morphology (biology), morphology of a scale can be used to identify the species of fish it came from. Scales originated within the jawless ostracoderms, ancestors to all jawed fishes today. Most Osteichthyes, bony fishes are covered with the cycloid scales of salmon and carp, or the ctenoid scales of perch, or the ganoid scales of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Batoidea
Batomorphi is a Division (taxonomy), division of Chondrichthyes, cartilaginous fishes, commonly known as rays, this taxon is also known as the Order (biology), superorder Batoidea, but the 5th edition of ''Fishes of the World'' classifies it as the division Batomorphi. They and their close relatives, the sharks, compose the subclass Elasmobranchii. Rays are the largest group of cartilaginous fishes, with well over 600 species in 26 families. Rays are distinguished by their flattened bodies, enlarged pectoral fins that are fused to the head, and gill slits that are placed on their ventral surfaces. Anatomy Batomorphs are flat-bodied, and, like sharks, are cartilaginous fish, meaning they have a boneless skeleton made of a tough, elastic cartilage. Most batomorphs have five ventral slot-like body openings called gill slits that lead from the gills, but the Hexatrygonidae have six. Batomorph gill slits lie under the pectoral fins on the underside, whereas a shark's are on the sides ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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, such as the great white shark, great white as well as less familiar ones, such as the goblin shark and megamouth shark. Members of the order are distinguished by possessing two dorsal fins, an anal fin, five gill, gill slits, eyes without nictitating membranes, and a mouth extending behind the eyes. Species in two families of Lamniformes – Lamnidae and Alopiidae – are distinguished for maintaining a higher body temperature than the surrounding waters. Members of the group include Macro-predator, macropredators, generally of medium-large size, including the largest macropredatory shark ever, the extinct ''Otodus megalodon,'' as well as large planktivores. Although some authors have argued that the Late Jurassic ''Palaeocarcharias'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carpet Shark
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 common name of sharks in the family Orectolobidae. Carpet sharks have five gill slits, two spineless dorsal fins, and a small mouth that does not extend past the eyes. Many species have barbel (anatomy), barbels. Characteristics The carpet sharks are a diverse group of sharks with differing sizes, appearances, diets, and habits. They first appeared in the fossil record in the Early Jurassic; the oldest known orectolobiform genera are ''Folipistrix'' (known from Toarcian to Aalenian of Belgium and Germany), ''Palaeobrachaelurus'' (Aalenian to Barremian) and ''Annea (fish), Annea'' (Toarcian to Bajocian of Europe). All species have two dorsal fins and a relatively short, transverse mouth that does not extend behind the eyes. Besides the nost ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chondrichthyes
Chondrichthyes (; ) is a class of jawed fish that contains the cartilaginous fish or chondrichthyans, which all have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fish'', which have skeletons primarily composed of bone tissue. Chondrichthyes are aquatic vertebrates with paired fins, paired nares, placoid scales, conus arteriosus in the heart, and a lack of opercula and swim bladders. Within the infraphylum Gnathostomata, cartilaginous fishes are distinct from all other jawed vertebrates. The class is divided into two subclasses: Elasmobranchii (sharks, rays, skates and sawfish) and Holocephali ( chimaeras, sometimes called ghost sharks, which are sometimes separated into their own class). Extant chondrichthyans range in size from the finless sleeper ray to the over whale shark. Anatomy Skeleton The skeleton is cartilaginous. The notochord is gradually replaced by a vertebral column during development, e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hexanchiformes
The Hexanchiformes Help:IPA/English, /hɛkˈsæŋkɪfɔːrmiːz/ are a primitive Order (biology), order of sharks, numbering just five extant species in two Family (biology), families, Chlamydoselachidae and Cow shark, Hexanchidae. Chlamydoselachidae are also known as frilled sharks, these sharks are very rare fishes and typically reside in deeper waters. Hexanchidae are also known as cow sharks and are the lesser known of the two types of Hexanchiformes and also reside in deep waters. Taxonomy Due to their primitive anatomy, hexanchiforms were previously considered the most Basal (phylogenetics), basal group of sharks. However, more recent phylogenetic studies indicate that while primitive, they in fact belong to the superorder Squalomorphi, which also contains Squalidae, dogfishes, angelsharks, and sawsharks, although they are thought to be the most basal member of the group. Description Hexanchiform sharks have one spineless dorsal fin located over or behind the pelvic fin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squaliformes
The Squaliformes are an order of sharks that includes about 126 species in seven families. Members of the order have two dorsal fins, which usually possess spines, they usually have a sharp head, no anal fin or nictitating membrane, and five to seven gill slits. In most other respects, however, they are quite variable in form and size. Most species of the squaliform order live in saltwater or brackish water. They are found worldwide, from northern to tropical waters, and from shallow coastal seas to the open ocean. All members of the family Etmoperidae and Dalatiidae and ''Zameus squamulosus'' possess photophores, luminous organs, and exhibit intrinsic bioluminescence. Bioluminescence evolved once in Squaliformes, approximately 111–153 million years ago, and helped the Squaliformes radiate and adapt to the deep sea. The common ancestor of Dalatiidae, Etmopteridae, Somniosidae, and Oxynotidae possessed a luminous organ and used bioluminescence for camouflage by co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sawshark
A sawshark or saw shark is a member of a shark order (Pristiophoriformes ) bearing a unique long, saw-like rostrum (snout or bill) edged with sharp teeth, which they use to slash and disable their prey. There are eight species within the Pristiophoriformes, including the longnose or common sawshark ('' Pristiophorus cirratus''), shortnose sawshark ('' Pristiophorus nudipinnis''), Japanese sawshark ('' Pristiophorus japonicas''), Bahamas sawshark ('' Pristiophorus schroederi''), sixgill sawshark ('' Pliotrema warreni''), African dwarf sawshark ('' Pristiophorus nancyae''), Lana's sawshark ('' Pristiophorus lanae'') and the tropical sawshark ('' Pristiophorus delicatus''). Sawsharks are found in many areas around the world, most commonly in waters from the Indian Ocean to the southern Pacific Ocean. They are normally found at depths around 40–100 m, but can be found much lower in tropical regions. The Bahamas sawshark was discovered in deeper waters (640 m to 915 m) of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elasmobranch
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 having five to seven pairs of gill slits opening individually to the exterior, rigid dorsal fins and small placoid scales on the skin. The teeth are in several series; the upper jaw is not fused to the cranium, and the lower jaw is articulated with the upper. The details of this jaw anatomy vary between species, and help distinguish the different elasmobranch clades. The pelvic fins in males are modified to create claspers for the transfer of sperm. There is no swim bladder; instead, these fish maintain buoyancy with large livers rich in oil. The definition of the clade is unclear with respect to fossil chondrichthyans. Some authors consider it as equivalent to Neoselachii (the crown group clade including modern sharks, rays, and all o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
