Reproduction in Animals - 1

Complete metamorphosis is found in butterflies.It is insect development in which egg, larval, pupal, and adult stages occur, each differing greatly in morphology.

When male differs from female in morphology, it is called sexual dimorphism. This differentiation happens in organisms who reproduce through sexual reproduction, with the prototypical example being for differences in characteristics of reproductive organs.

In sexual reproduction, there must be a union of one male and one female reproductive cell.

When larvae develops gonads and reproduces by normal sexual reproduction, it is called neoteny.For example, the adult axolotl, a salamander, retains larval external gills.

Viviparity is found in rabbit as it is a viviparous animal which give birth to living young that have been nourished in close contact with their mothers' bodies. 

Most terrestrial animals reproduce by internal fertilisation which takes place inside the female body.

Zygote is produced during sexual reproduction. It is a eukaryotic cell formed by a fertilization event between two gametes.

The developing embryo does not receive nourishment from mother's body in oviparous reproduction. 

Syngamy is fusion of nuclei of sperm and ovum. It is also called fertilization.

Asexual reproduction in a sponge Leucosolenia occurs by budding.

Natural parthenogenesis is found in aphids, honey bees and wasps.It is a form of asexual reproduction in which growth and development of embryos occur without fertilization.

Endogamy (self fertilisation) is observed in taenia,It involves the fusion of two types of gametes derived from the same parent (uni-parental) . It is a very rare process.

Testis is a primary sex organ  in males as it produces gametes.

Anisogamy is found in human beings, earthworms and pilas.Anisogamy refers to a form of sexual reproduction involving the union or fusion of two dissimilar gametes .The smaller gamete is considered to be male (sperm cell), whereas the larger gamete is regarded as female (egg cell).

The human sperm cell is haploid, so that its 23 chromosomes can join the 23 chromosomes of the female egg to form a diploid cell.

The Oviduct is the tube that links the ovary to the uterus and which the ovulated oocyte travels down to become fertilised by sperm present in the female tract. It is also refered to as the Fallopian tube, Uterine tube or Ovarian tube.

Ejaculation is a function of sympathetic nervous system.

The hormone progesterone is secreted by developing graafian follicles.

Among these, humans show viviparity as they give birth to young ones.