Internal fertilization
Overview
In mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s, internal fertilization is done through copulation
Mating
In biology, mating is the pairing of opposite-sex or hermaphroditic organisms for copulation. In social animals, it also includes the raising of their offspring. Copulation is the union of the sex organs of two sexually reproducing animals for insemination and subsequent internal fertilization...

, which involves the insertion of the penis
Penis
The penis is a biological feature of male animals including both vertebrates and invertebrates...

 into the vagina
Vagina
The vagina is a fibromuscular tubular tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. Female insects and other invertebrates also have a vagina, which is the terminal part of the...

. Some other higher vertebrate
Vertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...

 animals (most reptile
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...

s, most bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s, all dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

s , and some fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

) reproduce internally, but their fertilization is cloaca
Cloaca
In zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the intestinal, reproductive, and urinary tracts of certain animal species...

l.

The union of spermatozoa of the parent organism. At some point, the growing egg
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...

 or offspring
Offspring
In biology, offspring is the product of reproduction, of a new organism produced by one or more parents.Collective offspring may be known as a brood or progeny in a more general way...

 must be expelled. There are three general ways of doing this:
  • Oviparous
    Oviparity
    Oviparous animals are animals that lay eggs, with little or no other embryonic development within the mother. This is the reproductive method of most fish, amphibians, reptiles, all birds, the monotremes, and most insects, some molluscs and arachnids....

     organisms, including most insect
    Insect
    Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

    s and reptiles, monotreme
    Monotreme
    Monotremes are mammals that lay eggs instead of giving birth to live young like marsupials and placental mammals...

    s, dinosaurs and all birds lay eggs that continue to develop after being laid, and hatch later.

  • Viviparous
    Vivipary
    Vivipary has two different meanings. In animals, it means development of the embryo inside the body of the mother, eventually leading to live birth, as opposed to laying eggs...

    organisms, including almost all mammals (such as whale
    Whale
    Whale is the common name for various marine mammals of the order Cetacea. The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which belong to suborder Odontoceti . This suborder also includes the sperm whale, killer whale, pilot whale, and beluga...

    s, kangaroo
    Kangaroo
    A kangaroo is a marsupial from the family Macropodidae . In common use the term is used to describe the largest species from this family, especially those of the genus Macropus, Red Kangaroo, Antilopine Kangaroo, Eastern Grey Kangaroo and Western Grey Kangaroo. Kangaroos are endemic to the country...

    s and human
    Human
    Humans are the only living species in the Homo genus...

    s) bear their young live.
Encyclopedia
In mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s, internal fertilization is done through copulation
Mating
In biology, mating is the pairing of opposite-sex or hermaphroditic organisms for copulation. In social animals, it also includes the raising of their offspring. Copulation is the union of the sex organs of two sexually reproducing animals for insemination and subsequent internal fertilization...

, which involves the insertion of the penis
Penis
The penis is a biological feature of male animals including both vertebrates and invertebrates...

 into the vagina
Vagina
The vagina is a fibromuscular tubular tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. Female insects and other invertebrates also have a vagina, which is the terminal part of the...

. Some other higher vertebrate
Vertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...

 animals (most reptile
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...

s, most bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s, all dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

s , and some fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

) reproduce internally, but their fertilization is cloaca
Cloaca
In zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the intestinal, reproductive, and urinary tracts of certain animal species...

l.

The union of spermatozoa of the parent organism. At some point, the growing egg
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...

 or offspring
Offspring
In biology, offspring is the product of reproduction, of a new organism produced by one or more parents.Collective offspring may be known as a brood or progeny in a more general way...

 must be expelled. There are three general ways of doing this:
  • Oviparous
    Oviparity
    Oviparous animals are animals that lay eggs, with little or no other embryonic development within the mother. This is the reproductive method of most fish, amphibians, reptiles, all birds, the monotremes, and most insects, some molluscs and arachnids....

     organisms, including most insect
    Insect
    Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

    s and reptiles, monotreme
    Monotreme
    Monotremes are mammals that lay eggs instead of giving birth to live young like marsupials and placental mammals...

    s, dinosaurs and all birds lay eggs that continue to develop after being laid, and hatch later.

  • Viviparous
    Vivipary
    Vivipary has two different meanings. In animals, it means development of the embryo inside the body of the mother, eventually leading to live birth, as opposed to laying eggs...

    organisms, including almost all mammals (such as whale
    Whale
    Whale is the common name for various marine mammals of the order Cetacea. The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which belong to suborder Odontoceti . This suborder also includes the sperm whale, killer whale, pilot whale, and beluga...

    s, kangaroo
    Kangaroo
    A kangaroo is a marsupial from the family Macropodidae . In common use the term is used to describe the largest species from this family, especially those of the genus Macropus, Red Kangaroo, Antilopine Kangaroo, Eastern Grey Kangaroo and Western Grey Kangaroo. Kangaroos are endemic to the country...

    s and human
    Human
    Humans are the only living species in the Homo genus...

    s) bear their young live. The developing young spend proportionately more time within the female's reproductive tract. The young are later released to survive on their own, with varying amounts of help from the parent
    Parent
    A parent is a caretaker of the offspring in their own species. In humans, a parent is of a child . Children can have one or more parents, but they must have two biological parents. Biological parents consist of the male who sired the child and the female who gave birth to the child...

     (s) on the species
    Species
    In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

    .

  • Ovoviviparous
    Ovoviviparity
    Ovoviviparity, ovovivipary, or ovivipary, is a mode of reproduction in animals in which embryos develop inside eggs that are retained within the mother's body until they are ready to hatch...

     organisms, like the garter snake
    Garter snake
    The Garter snake is a Colubrid snake genus common across North America, ranging from Alaska and Canada to Central America. It is the single most widely distributed genus of reptile in North America. The garter snake is also the Massachusettsstate reptile.There is no real consensus on the...

    , and the Madagascar hissing cockroach
    Madagascar hissing cockroach
    The Madagascar hissing Cockroach , also known as the Hissing Cockroach or simply Hisser, is one of the largest species of cockroach, reaching 2–4 inches at maturity. They are from the island of Madagascar off the African coast, where they can be found in rotting logs.Unlike most cockroaches, they...

    , have eggs (with shells
    Eggshell
    An eggshell is the outer covering of a hard-shelled egg and of some forms of eggs with soft outer coats.- Insect eggs :Insects and other arthropods lay a variety of styles and shapes of eggs. Some have gelatinous or skin-like coverings, others have hard eggshells. Softer shells are mostly protein....

    ) that hatch as they are laid, making it look like "live birth".


Most species of land animals reproduce by internal fertilization. For example: All reptiles, such as the snake and turtle reproduce by internal fertilization. Males and females usually have an opening called the cloaca through which semen, urine and feces can be released. During mating, the male and female join their cloacas. The male releases semen into the female's cloaca. The spermatozoa then travel up a canal to reach the ova.
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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