Internal fertilization is a form of animal fertilization of an ovum by spermatozoon within the body of an inseminated animal, whether female or hermaphroditic. This is distinct from external fertilization, where the union of the ova and spermatoza occur outside of the organism. Phyla Subregnum Parazoa Porifera (sponges) Subregnum Agnotozoa Placozoa (trichoplax) Orthonectida (orthonectids) Rhombozoa (dicyemids) Subregnum Eumetazoa Radiata (unranked) (radial symmetry) Ctenophora (comb jellies) Cnidaria (coral, jellyfish, anemones) Bilateria (unranked) (bilateral symmetry) Acoelomorpha (basal) Orthonectida (parasitic to flatworms, echinoderms, etc. ... Categories: Biology stubs ... A human ovum An ovum (from Latin, loosely, egg or egg cell) is a female sex cell or gamete. ... The signifier sperm can refer to: (mass noun, from Greek sperma = seed) a substance which consists of spermatozoa and which is a component of semen (mass noun) semen itself (informally, count noun with plural sperm or sperms) a single spermatozoon (= sperm cell) sperma ceti (Latin ceti, genitive of cetus = whale... Insemination is the introduction of semen into the genital tract of a female. ... The mirror of the Roman Goddess Venus is often used to represent the female sex. ... The 1st-century BC sculpture The Reclining Hermaphrodite, in the Museo Palazzo Massimo Alle Terme in Rome In zoology, a hermaphrodite is an organism of a species whose members possess both male and female sexual organs during their lives. ... External fertilization is a form of fertilization in which a sperm cell is united with an egg cell external to the body of the female. ...

In mammals, internal fertilization is accomplished through copulation, which involves the insertion of the penis into the vagina. Some other higher vertebrates animals (most reptiles, most birds, some fish) reproduce internally, but their fertilization is cloacal. Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals primarily characterized by the presence of mammary... It has been suggested that Mating be merged into this article or section. ... The penis (plural penises or penes) or phallus is an external male sexual organ. ... Human female internal reproductive anatomy. ... Phyla Subregnum Parazoa Porifera (sponges) Subregnum Agnotozoa Placozoa (trichoplax) Orthonectida (orthonectids) Rhombozoa (dicyemids) Subregnum Eumetazoa Radiata (unranked) (radial symmetry) Ctenophora (comb jellies) Cnidaria (coral, jellyfish, anemones) Bilateria (unranked) (bilateral symmetry) Acoelomorpha (basal) Orthonectida (parasitic to flatworms, echinoderms, etc. ... In zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the intestinal, urinary, and genital tracts of certain animal species. ...

The union of spermatozoon and ovum produces a zygote, which develops into an embryo, which, in turn, continues to develop inside the parent organism. At some point, the growing egg or offspring must be expelled. There are three general ways of doing this: This article or section does not cite its references or sources. ... Embryos (and one tadpole) of the wrinkled frog (Rana rugosa). ... An average Whooping Crane egg is 102 mm long, and weighs 208 grams In some animals, an egg (Latin ovum) is the zygote, resulting from fertilization of the ovum. ... In biology, offspring are the product of reproduction, a new organism produced by one or more parents. ...

• Oviparous organisms, including most insects and reptiles, and all birds lay eggs that continue to develop after being laid, and hatch later.

• Viviparous organisms, including all mammals (such as whales, kangaroos and humans) 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(s) depending on the species.

• Ovoviviparous organisms, like garter snakes, and the Madagascar Hissing Cockroach, have eggs (with shells) that hatch as they are laid, making it look like "live birth."

Classes & Orders See taxonomy Insects are invertebrate animals of the Class Insecta, the largest and (on land) most widely-distributed taxon within the phylum Arthropoda. ... Orders  Crocodilia - Crocodilians scary crocodiles. ... For other meanings of bird, see bird (disambiguation). ... A viviparous animal is an animal employing vivipary, a method of reproduction in which the embryo develops inside the body of the mother from which it gains nourishment, and not from an egg. ... Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals primarily characterized by the presence of mammary... Whales are the largest species of exclusively aquatic mammals, members of the order Cetacea, which also includes dolphins and porpoises. ... Species Macropus rufus Macropus giganteus Macropus fuliginosus A kangaroo is any of several large macropods (the marsupial family that also includes the wallabies, tree-kangaroos, wallaroos, pademelons and the Quokka: 65 species in all). ... Human beings are defined variously in biological, spiritual, and cultural terms, or in combinations thereof. ... Reproduction is the creation of one thing as a copy of, product of, or replacement for a similar thing, e. ... Ovoviviparous animals develop within eggs that remain within the mother up until they hatch or are about to. ... Species Many; see article. ... Families Blaberidae Blattellidae Blattidae Cryptocercidae Polyphagidae Nocticolidae Cockroaches are insects of the order Blattodea (the name Blattaria is sometimes used). ...

References

• University of Cincinati Clermont College