Vertebrates: Animals
with a backbone
How we can remember
which classes are
vertebrates:
The “B-Farm” : Birds,
Fish, Amphibians,
Reptiles, Mammals
With a few exceptions,
almost all vertebrates
reproduce sexually
through fertilization.
Fertilization is the process
in which an egg cell and a
sperm cell join to form a
new organism.
Fertilization can be
internal or external.
Internal Fertilization:
Sperm and Egg are joined
within the body of animal
(usually the mother)
External Fertilization:
Sperm and Egg are joined
outside the body of animal
BIRDS:
• Internal Fertilization
• Development of egg within
environment
FISH:
• Internal and External Fertilization
• Egg develops:
- within environment (majority of
fish)
-OR- within female body egg hatches
within body prior to birth
(Seahorses, pipefish)
(Exception: Egg develops in male
seahorses)
Amphibians:
• Internal and External
Fertilization
• Egg develops within
environment (Frogs)
-OR• Young develops internally
(caecilians)
REPTILES:
• Internal Fertilization
• Egg can develop:
- within environment (turtles,
crocodile)
-OR- within female body egg hatches
within body prior to birth (garter
snake)
-OR –
-Young develops internally (boas,
vipers)
MAMMALS:
• Internal Fertilization
• Young develops internally
(majority of all mammals)
-OR•Egg develops within
environment (Ex: platypus)