Transcript Development and Growth

Development and Growth
Where Do Embryos Develop?
• Growing offspring, or the embryo, may develop
outside or inside of the parent’s body.
• The offspring of some animals develop inside an
egg laid outside of the parent’s body.
• Most animals without backbones lay eggs.
• The eggs of land vertebrates such as reptiles
and birds, that develop in an egg outside of the
parent’s body are called amniotic eggs.
Amniotic Egg
Egg Retaining Animals
• In some animals, an
embryo develops
inside an egg that is
kept within the
parent’s body.
• The developing
embryo gets all of its
nutrients from the
egg’s yoke.
• What are some eggretaining mammals
that you can think of?
Placental Mammals
• In placental mammals
the embryo develops
inside the mother’s body.
• What are some
examples of placental
mammals?
• Materials are exchanged
between the embryo and
the mother through an
organ called the
placenta.
Placental Mammals
• Blood carrying food and oxygen from the mother
flows to the placenta and then the embryo.
• Blood carrying wastes and carbon dioxide from
the embryo flows to the placenta and then to the
mother.
• The mother’s blood does not mix with the
embryo’s blood and the placental mammal
develops inside the mother’s body until its body
systems can function on their own.
Placental Mammals
How Do Young Animals
Develop?
• Some animals look like
small versions of
adults.
• Other animals go
through a process of
metamorphosis, or
major body changes, as
they develop from
young organisms into
adult organisms.
• What are some
examples of animals
that undergo
metamorphosis?
Crustaceans
• Most crustaceans such as lobsters begin
their lives as tiny, swimming, larvae that do
not resemble adults.
• Through metamorphosis, crustacean
larvae develop into adults.
Insects
• Insects undergo
complete or
incomplete
metamorphosis.
Complete Metamorphosis
• Complete metamorphosis
had 4 stages: egg, larva,
pupa, and adult.
• In the pupa stage the
insect is enclosed in a
protective covering and
major changes in body
structures are taking
place.
• The pupa does not eat
and moves very little.
Incomplete Metamorphosis
• Incomplete
metamorphosis has no
distinct larval stage and
has 3 stages: egg,
nymph, and adult.
• An egg hatches into a
nymph which usually
looks like an adult without
wings.
• As the nymph grows it
may shed it’s exoskeleton
several times.
Amphibians
• Amphibians such as frogs
begin their life cycles as
fertilized eggs in water.
• The larva of a frog is
called a tadpole.
• The frog undergoes
metamorphosis to
become an adult.
• Does a frog go through
complete or incomplete
metamorphosis?
How Do Animals Care For Their
Young?
• Most amphibians and reptiles do not
provide parental care, while most birds
and mammals typically care for their
offspring.
• Offspring that do not receive parental care
must be able to care for themselves from
their time of birth.
Parental Care
• Most bird species lay their eggs in nests
that one or both parents build.
• Some species can move around and find
food right after they hatch while others are
helpless and must be fed by the parent.
• Most parent birds feed and protect their
young until they are able to care for
themselves.
Parental Care
• Most mammals are usually quite helpless
for a long time after they are born.
• All young mammals are fed with milk from
the mother’s body and one or both parents
may continue caring for their offspring until
the young animals are independent.