Reproduction In Vertebrae & Strategies Flashcards
Internal fertilization
Occurs when sperm cells from male is transferred into female to fuse with ovum by copulation
Advantages of internal fertilisation
Ensures sperm cell comes into contact with ovum
Developing Embryo is protected from predators
Developing Embryo is removed from harsh environments
Disadvantages of internal fertilisation
Fewer eggs are produced
The animal must have copulatory organ to insert sperm cells into female body
External fertilisation
Fertilisation occurs outside of body where male and female gamete are released into the water and sperm cell swims /is carried to the ovum.
Disadvantage of external fertilisation
Does not have a protective shell
Requires a moist environment as it dries easily
Many eggs end up not being fertilized
Advantage of external fertilisation
Water prevents egg from drying out
Water allows sperm cell to swim towards egg
Has a jelly like substance to protect developing Embryo
Has a jelly like substance that allows exchange of gases between Embryo & water
Ovums and sperm produced in large amounts
Ovipary
Egg laying animals
How does ovipary work
Eggs are laid and development of organism is completed inside the ovum.
Some eggs are protected by a hard shell while others are protected by jelly like layer
Seem in frogs, insects, birds
Advantages of ovipary
Ova & sperm cells are produce in large numbers to increase chances of survival to adulthood
Parental care ensures survival to adulthood
Disadvantages of ovipary
Mortality rate is high
Much energy is invested for parental care
Ovovivipary
Animals that produce Ovums kept in their bodies until they hatch (body temperature keeps them warm until they hatch)
No connection between mother & egg & some examples include some snakes, lizards, sharks
Advantages of ovovivipary
Young one is protected from cold & predators to ensure survival
Young one can develop to a fairly large size before birth
Disadvantages of ovovivipary
Fewer offspring are born
More energy is used by female carrying the eggs
Vivipary
Animals that give birth to live young offspring
A connection exists between developing foetus & mother
Examples are dogs and humans
Advantages of vivipary
Temperature is regulated by mother
Mother provides nutrition
Mortality rate is lower
Embryo is protected by mothers body
More efficient development as nutrients are received for longer period from mothers blood through placenta
Disadvantages of vivipary
Number of offspring produced is few
More energy is used to provide parental care
Amniotic egg
A membrane that exists in oviparous Vertebrates that surrounded Embryo
Structure of amniotic egg
Shell
Amniotic cavity
Amnion
Albumen
Allantois
Chorion
Embryo
Yolk
Yolk sac
(SAAAACEYY)
Amnion
Encloses Embryo
Albumen
A white, soft, runny substance rich in protein which supplies water to Embryo
Yolk
Serves as the food supply for Embryo
Chalaza
Support Yolk
Anchors Yolk
Allows Yolk to rotate and keep germinal disc on top side, close to hens body
Germinal disc
Small pale spot where Embryo will develop
Shell
Waterproof Layer providing protection but allows porous gases. The air space is below and assists with exchange of gases into & from egg
Allantois
Stores excretory products from Embryo
Provide transport for gases absorbed from air space
Chorion
Surrounds all other membranes
What is altricial development
Where the young are helpless at birth and need considerable parental care. Without this care they would not survive
Characteristics of Altricial development
Characteristics of Altricial development species
Spends its time developing before being born but tend to grow faster & develop after birth
Small bodies, shorter life cycle
What is precocial development
Precocial development
The young are born with a high degree of independence able to walk, run, swim.
Characteristics of precocial development
Characteristics
Important to avoid predators
Large bodies, breed less
Spend more time developing before birth & so are more alert & physically developed at birth.
Common for prey species as development depends on it
What is parental care
Parental Care
Providing a nurturing & protected environment in which the young can grow & develop.
More energy & time required
Give rise to few offspring
Relationship between Altruism and parental care
Relationship between Altruism & parental care
The young of altricial species are helpless & therefore need this care which is why this behavior is better developed in altricial species
Advantages of amniotic egg
Resistant to dehydration. Oviparous animals can move into various environments.
Protected by number of membranes
Allow animals to evolve into bigger forms & better protect themselves
