Internal Fertilization
Internal fertilization is a reproductive strategy where fertilization occurs inside the
female’s body. This method is common among various groups of animals, particularly
land-based species, but it is also found in some aquatic organisms.
1. Mammals: Most mammals exhibit internal fertilization, where the male deposits
sperm directly into the female’s reproductive tract. This group includes:
Humans (Homo sapiens): Humans
Dogs (Canis lupus familiaris):
Dogs also engage in matingreproduce through sexual
behaviors that facilitate intercourse,
internal leading to internal
fertilization. fertilization.
2.Cartilaginous Fish: Some sharks and rays utilize internal fertilization.
For example:
Great White Shark (Carcharodon Hammerhead Shark (Sphyrna
carcharias): This species has a unique spp.): Similar to great whites,
reproductive process where males use hammerhead sharks also
claspers to transfer sperm to females practice internal fertilization.
internally.
3. Reptiles: Many reptiles reproduce via internal fertilization. Examples include:
Lizards (Lacertilia): Most lizard Snakes (Serpentes): Many
species have internal fertilization; snakes, such as the garter snake
for instance, the green iguana (Thamnophis sirtalis), utilize this
(Iguana iguana). method.
4. Birds: Although birds lay eggs externally, they still undergo internal
fertilization before laying their eggs. Examples include:
Chickens (Gallus gallus Eagles (Aquila spp.): Eagles also
domesticus): Chickens mate engage in mating that leads to
internally before producing eggs. internal fertilization.
5. Some Invertebrates: Certain invertebrates exhibit forms of internal fertilization
as well:
Some Species of Sea Slugs
Cockroaches (Blattodea): The
(Nudibranchia): Certain
Madagascar hissing cockroach
nudibranchs have been observed
(Gromphadorhina portentosa)
to engage in mating behaviors that
practices internal fertilization.
involve internal sperm transfer.
External Fertilization
External fertilization is a reproductive strategy commonly found in aquatic environments,
where eggs and sperm are released into the water for fertilization to occur. This method is
prevalent among various groups of animals, particularly those that live in or near water.
1. Fish: Most fish species utilize
external fertilization. During
spawning, females release eggs
into the water while males
simultaneously release sperm. This
process can be observed in many
types of fish, including salmon and
trout.
2. Amphibians: Many amphibians also
exhibit external fertilization, particularly
during their breeding season when they
return to aquatic environments. Frogs
are a prime example; female frogs lay
eggs in water, and males release sperm
over them to achieve fertilization.
3. Echinoderms: This group includes sea
urchins and starfish, which also reproduce
through external fertilization. They typically
engage in mass spawning events where
both eggs and sperm are released into the
ocean simultaneously.
4. Mollusks: Certain mollusks,
such as oysters and clams, also
undergo external fertilization by
releasing their gametes into the
water column during specific
times of the year.
Crustaceans: Many crustaceans
like crabs and shrimp use
external fertilization as well,
where females release eggs into
the water for males to fertilize.
Submitted by: Group1.
Darren Vaugn Llanda
Martina Lexie Alunan
Lealyn Elisterio
John Emmanuel Elimanao Grade 5- ESM
John Jacob Granzo
Rein Margarette Arangga
Sofie Solen
Alyssa Anne Bancolo
Submitted to :
Ma’am Alumbro
