Sexuality in Animals

Specialized reproductive organs that produce gametes in animals are called gonads.

The male gonad that produces sperms (male gametes) is called the testis.

The female gonad that produces ova (female gametes) is called the ovary.

Animals in which an individual possesses either male or female reproductive organs are called unisexual animals.

An organism that has both male and female reproductive organs in the same body is called a hermaphrodite.

In animals, the juvenile phase is followed by a period of morphological and physiological changes that lead to reproductive maturity and active reproductive behaviour. Once sexual maturity is attained, male and female gametes are produced in specialised reproductive organs called gonads.

In higher animals, sperms and ova are produced in specialized sex organs known as gonads, namely testis in males and ovary in females. Based on the distribution of reproductive organs, animals may broadly be grouped into unisexual forms and hermaphrodite forms.

In unisexual animals, sexes are separate. One individual functions as male and another functions as female.

Examples: Cockroach

A-B. Cockroach: a unisexual animal. Note that both male (A) and female (B) sex organs are present on two different individuals.

Many vertebrates such as humans and birds follow the same general pattern of separate sexes as a biological model of unisexuality.

In hermaphrodite animals, both male and female reproductive organs are present in the same individual.

Examples:

• Earthworm
• Tapeworm
• Leech

Although both reproductive systems are present in one body, cross-fertilization is commonly observed in these animals.

Earthworm: a bisexual animal. Note that both male and female sex organs are present on the same individual.

• After the juvenile phase, animals undergo changes leading to reproductive maturity, then produce gametes in organs called gonads - testis in males (sperms), ovary in females (ova).
• By distribution of reproductive organs, animals are grouped into unisexual and hermaphrodite forms.
• In unisexual animals, sexes are separate, as in cockroaches, humans, and birds.
• In hermaphrodite animals, both sex organs occur in the same individual (earthworm, tapeworm, leech), but cross-fertilization is common.