Osteichthyes

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Osteichthyes

Osteichthyes , also called bony fish, are a taxonomic

Taxonomy

Taxonomy is the practice and science of classification. The word comes from the Greek language ', taxis and ', nomos .Taxonomies, or taxonomic schemes, are composed of taxonomic units known as taxa , or kinds of things that are arranged frequently in a hierarchical structure....
group of fish

Fish

A fish is any marine biology vertebrate animal that is typically ectothermic , covered with scale , and equipped with two sets of paired fins and several unpaired fins....
that includes the ray-finned fish (Actinopterygii

Actinopterygii

The Actinopterygii constitute the Class of the ray-finned fishes.The ray-finned fishes are so called because they possess lepidotrichia or "fin rays", their fins being webs of skin supported by bony or horny spines , as opposed to the fleshy, lobed fins that characterize the class Sarcopterygii....
) and lobe finned fish (Sarcopterygii

Sarcopterygii

Sarcopterygii - Crossopterygii is traditionally the class of fleshy-finned, lobe-finned fishes, consisting of lungfish, and coelacanths....
). The split between these two classes occurred around 440 mya

Mya (unit)

In astronomy, geology, and paleontology, mya or "m.y.a." is an abbreviation for "million years ago". Like the related unit bya, mya is traditionally written in lower case....
.

In most classification systems the Osteichthyes are paraphyletic with land vertebrates. That means that the nearest common ancestor of all Osteichthyes includes tetrapod

Tetrapod

Tetrapods are vertebrate animals having four feet, legs or leglike appendages. Amphibians, reptiles, dinosaurs/birds, and mammals are all tetrapods, and even the limbless snakes are tetrapods by descent....
s amongst its descendants. Actinopterygii

Actinopterygii

Sarcopterygii

Sarcopterygii - Crossopterygii is traditionally the class of fleshy-finned, lobe-finned fishes, consisting of lungfish, and coelacanths....
in Osteichthyes causes Osteichthyes to be paraphyletic.

Most bony fish belong to the Actinopterygii; there are only eight living species of lobe finned fish (Sarcopterygii), including the lungfish

Lungfish

Coelacanth

Coelacanth is the common name for an Order of fish that includes the oldest living Lineage of gnathostomata known to date. The coelacanths, which are related to lungfishes and tetrapods, were believed to have been extinction since the end of the Cretaceous period, until the first Latimeria specimen was found off the east coast of Sout...
s.

They are traditionally treated as a class of vertebrates, with subclasses Actinopterygii and Sarcopterygii, but some newer schemes divide them into several separate classes.

The vast majority of fish are osteichthyes.

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Characteristics

Osteichthyans are characterized by a relatively stable pattern of cranial bones, rooted, medial insertion of mandibular

Mandible

The mandible or inferior maxillary bone forms the lower jaw and holds the lower tooth in place. It also refers to both the upper and lower sections of the beaks of birds....
muscle in lower jaw. The head and pectoral girdle

Pectoral girdle

The pectoral girdle is the set of bones which connect the upper limb to the axial skeleton on each side. It consists of the clavicle and scapula in humans and, in those species with three bones in the pectoral girdle, the coracoid....
s are covered with large dermal bones. The eyeball is supported by a sclerotic ring

Sclerotic ring

Sclerotic rings are rings of bone found in the eyes of several groups of vertebrate animals, except for mammals and crocodilians. They can be made up of single bones or small bones together....
of four small bones, but this characteristic has been lost or modified in many modern species. The labyrinth in the inner ear

Inner ear

The inner ear is the labyrinth , a system of passages comprising two main functional parts:* the organ of hearing, or cochlea* and the vestibular apparatus, the organ of balance that consists of three semicircular canals and the Vestibule of the ear....
contains large otolith

Otolith

An otolith, , also called statoconium or otoconium is a structure in the saccule or Utricle of the inner ear, specifically in the Labyrinth ....
s. The braincase, or neurocranium, is frequently divided into anterior and posterior sections divided by a fissure

Fissure

In anatomy, fissure is a groove, natural division, deep furrow, cleft, or tear in various parts of the body....
.

Bony fish typically have swim bladders, which helps the body create a neutral balance between sinking and floating. However, these are absent in many species, and have developed into primitive lungs in the lungfishes. They do not have fin spines, but instead support the fin with lepidotrichia

Lepidotrichia

Lepidotrichia are bony, bilaterally-paired, segmented fin rays found in Osteichthyes. They develop around actinotrichia as part of the dermal exoskeleton....
(bone fin rays). They also have an operculum

Operculum (fish)

The operculum of a Osteichthyes is the hard bony flap covering and protecting the gills. In most fish, the rear edge of the operculum roughly marks the division between the head and the body....
, which helps them breathe without having to swim.

They also are able to see in colour, unlike most other fish.

Bony fish have no placoid scales. Mucous glands coat the body. Most have scales of sort: ganoid, cycloid, or cytenoid. These scales are smooth and overlapping.

Skeleton

The skeleton is made of bone and cartilage, and is almost completely calcified. The vertebral column, cranium, jaw, ribs, and intramuscular bones make up the skeleton.

One of the best-known innovations of the osteichthyans is endochondral bone

Endochondral ossification

Endochondral ossification is one of the two processes during fetal development of the mammal skeleton in which bone tissue is created. It is also an essential process during the rudimentary formation of long bones, the growth of the Epiphyseal plate of long bones, and the healing of bone healing....
or "replacement" bone, which is bone ossified internally, by replacement of 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....
, as well as perichondrally, as "spongy bone." In vertebrates, in general, there are various types of calcified tissue: dentine, enamel

Tooth enamel

Tooth enamel is the hardest and most highly mineralized substance of the body, and with dentin, cementum, and Pulp is one of the four major tissues which make up the tooth in vertebrates....
(or "enameloids") and bone

Bone

Bones are rigid organ that form part of the endoskeleton of vertebrates. They function to move, support, and protect the various organs of the body, produce red blood cell and white blood cells and store minerals....
, plus variants characterized by their ontogeny, chemistry, form and location. But endochondral bone is unique because it begins life as cartilage.

In lower vertebrates, cartilaginous structures can become superficially calcified. However, in osteichthyans, the circulatory system invades the cartilaginous matrix. This permits the local osteoblasts (bone-forming cells) to continue bone formation within the cartilage and also recruits additional, circulating osteoblasts. Other cells gradually eat away at the surrounding cartilage. The net result is that the cartilage is replaced from within by a somewhat irregular vascularized network of bone. Structurally, the effect is to create a relatively lightweight, flexible, "spongy" bone interior, surrounded by an outline of dense, lamellar periostial bone. Since this bone now surrounds other bone, rather than cartilage, it is referred to as periostial rather than perichondral. This is the unique endochondral bone from which the osteichthians derived their name, as well as many structural advantages. However useful endochondral bone may be, it is also much heavier and less flexible than cartilage. Thus, many modern osteichthyan groups, including the extremely successful teleosts, have evolved away from extensive use of endochondral bone.

Biology

Most bony fish breathe through gill

Gill

A gill is an anatomical structure found in many aquatic ecosystem organisms. It is a respiration organ whose function is the extraction of oxygen from water and the excretion of carbon dioxide....
s.

Lungfish

Lungfish

Lungfish are freshwater fish belonging to the Subclass Dipnoi. Lungfish are best-known for retaining characteristics primitive within the Osteichthyes, including the ability to breathe air, and structures primitive within Sarcopterygii, including the presence of lobed fins with a well-developed internal skeleton....
and other osteichthyan species, are capable of respiration through lungs or vascularized swim bladders. Other species can respire through their skin, intestines, and/or stomach.

Osteichthyes are ectothermic (cold blooded), meaning that their body temperature is dependent on that of the water. They can be any type of heterotroph

Heterotroph

A heterotroph is an organism that organic compound substrates to get its Energy#Chemical energy for its life cycle. This contrasts with autotrophs such as plants which are able to directly use sources of energy such as light to produce organic substrates from inorganic carbon dioxide....
: omnivore

Omnivore

Omnivores are species that eating both plants and animals as their primary food source. They are opportunistic, general feeders not specifically adapted to eat and digest either meat or plant material exclusively....
, carnivore

Carnivore

A carnivore , meaning 'meat eater' , is any animal with a diet consisting mainly of meat, whether it comes from animals living or dead .In a more general sense, an animal may be considered a carnivore if it prefers feeding on animal matter over plant matter....
, herbivore

Herbivore

Herbivory is a form of predation in which an organism, known as an herbivore, heterotrophs principally autotrophs such as plants, algae and photosynthesizing bacteria....
, or detrivore.

Some bony fish are hermaphrodite

Hermaphrodite

A hermaphrodite is an organism having both male and female reproductive organs. In many species, hermaphroditism is a common part of the life-cycle, enabling a form of sexual reproduction in which partners are not separated into distinct male and female types of individual....
s. Fertilization is usually external, but can be internal. Development is usually oviparous (egg-laying) but can be ovoviviparous, or viviparous. Although there is usually no parental care after birth, before birth parents may scatter, hide, guard or brood eggs.

Examples

The ocean sunfish

Ocean sunfish

File:Mondfisch_Ozenarium_Lissabon_20090228.ogvThe ocean sunfish, Mola mola, or common mola, is the heaviest known Osteichthyes in the world....
is the most massive bony fish in the world, while the longest is oarfish

Oarfish

Oarfish are large, greatly elongated, pelagic Lampriform fish comprising the small family Regalecidae. Found in all temperate to tropical oceans yet rarely seen, the oarfish family contains four species in two genus....
. Specimens of ocean sunfish have been observed up to in length and weighing up to . Other very large bony fish include the Atlantic blue marlin

Atlantic blue marlin

The Atlantic blue marlin is a species of marlin, endemic to the Atlantic Ocean. It is a predator that feeds on a wide variety of organisms near the surface....
, some specimens of which have been recorded as in excess of , the black marlin

Black marlin

The black marlin is a species of marlin found in tropical and subtropical Indo-Pacific oceans not far from the surface. It is a large commercial game fish with a maximum published weight of 750 kg, but greater weights are known....
, some sturgeon

Sturgeon

Sturgeon is the common name used for some 26 species of fish in the family Acipenseridae, including the genus Acipenser, Huso, Scaphirhynchus and Pseudoscaphirhynchus....
species, the giant grouper

Giant grouper

The giant grouper , also known as the brindle bass , brown spotted cod , bumblebee grouper and as the Queensland groper in Australia, is the largest bony fish found in coral reefs, and the aquatic emblem of Queensland, Australia....
and the goliath grouper

Goliath grouper

The Atlantic goliath grouper or itajara is a large saltwater fish of the grouper family. It was formerly known as the jewfish; however, in 2001 the American Fisheries Society made the decision to change the name to the more considerate "goliath grouper"....
, both which can exceed in weight. In contrast, the dwarf pygmy goby measures a minute .

Arapaima
Arapaima

The arapaima, pirarucu, or paiche is a South American tropical fresh water fish. It is one of the largest fresh water fish in the world....
gigas is the largest species of freshwater bony fish. The largest bony fish ever was Leedsichthys
Leedsichthys

Leedsichthys problematicus was a giant pachycormid that lived in the oceans of the Middle Jurassic period. The closest living relative of the pachycormids is the bowfin, Amia calva, but this is only very distantly related....
.

Osteichthyes

Characteristics

Skeleton

Biology

Examples

See also