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KINGDOM: ANIMALIA

SEXUAL REPRODUCTION

CHRISTHARINA SGsgchristharina@preuni.unimas.my

http://farm9.staticflickr.com/8448/7991284064_9281a6e1f4_z.jpg

1. Differentiate between internal and external fertilisation

2. Differentiate the three types of embryos’ development

3. Briefly describe the mating behaviour and the reproductive organs involved

Learning Objectives:

Fertilization can be internal or external

Animals can be grouped into three categories based on the embryonic development:

1. Oviparity2. Viviparity 3. Ovoviviparity

http://farm4.staticflickr.com/3444/3268077745_fd24bd675f_z.jpg

External vs Internal Fertilisation EXTERNAL INTERNAL

Sperms cell unites with the egg cell outside the female body

Sperms are deposited in or near reproductive tract and the union takes place within the female body

Environmental cues and body chemicals such as pheromones ensure sperms and eggs released at the same time and in close proximity

Requires complementary mating behavior and reproductive organs between the two sexes.

Characteristics of aquatic animals such as coral, Hydra, fish and amphibians (frogs, toads)

Characteristic of salamander (amphibian), reptiles, birds and mammals (higher vertebrates)

Large numbers of eggs but low survival rate Small numbers of eggs but high survival rate

Massive zygotes Fewer zygotes

Lack/No parental care Parental Care

High number of gametes Low number of gametes

Eggs lack of covering; jelly like membrane for amphibian

Amniotic eggs were covered with calcareous shells

EXTERNAL INTERNAL

Sperms cell unites with the egg cell outside the female body

Sperms are deposited in or near reproductive tract and the union takes place within the female body

Environmental cues and body chemicals such as pheromones ensure sperms and eggs released at the same time and in close proximity

Requires complementary mating behavior and reproductive organs between the two sexes.

A Male and Female common frog in amplexus. The purpose of amplexus is to ensure the male is in the optimal position to fertilize the female’s eggs as she lays them.

Foam nest

Massive zygotes Fewer zygotes

Frogspawn

High number of gametes Low number of gametes

Fish gametes

Frog gametes

Lack/No parental care Parental Care

Exception!!

A female frog that swallows its eggs or carrying on the back to protect them.

A female salamander (amphiumas) coiled around her nest to protect the egg from predators

egg

Where is mommy and daddy?

Parental care is a diagnostic character for aves and mammals

http://mariannedenazareth.blogspot.com/2011/08/parental-care.html http://www.dreamstime.com/stock-photography-parental-care-image8250792

Oviparity Ovoviviparity Viviparity

Lay eggs Eggs developed in female’s body until hatch

Live birthDevelopment of the embryos in female’s body

External and internal fertilization

Internal fertilization Internal fertilization

No nutrition is provided to the developing embryo except for egg’s yolk

The embryo obtains its nutrients and oxygen from the female via placenta. After live birth the young can survive with the supervision from its mother

The embryos of animals undergo three types of development as below:

Oviparity

https://i.ytimg.com/vi/ihaR-_SDemE/maxresdefault.jpg

http://www.findaspider.org.au/find/spiders/images/SalticidInsectEggs.jpg

Yolk in the eggs provides nutrients that will sustain development of the young.

http://www.bio.gc.ca/sharks/images/reproduction-fig14.jpg

Viviparity

Ovoviviparity

http://askwhy.co.uk/dinosauroids/wp-content/uploads/2012/03/snake_live_birth.jpg

The mother gives birth to young that recently hatched in her body. The young were nourished by egg yolk, not by their mother.

Embryo are nourished by the placenta; the organ which allows nutrients from the maternal blood to diffuse to the embryo, and expelled at birth.