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During external fertilization, many gametes are released into the water by each sex at the same time and place.
This type of fertilization requires water because animal sperm must swim to the eggs. Water also protects the gametes from drying out.
Species which have external fertilization are either aquatic or return to water for reproduction.
Wiki User
∙ 12y ago
Wiki User
∙ 12y agoLand animals don't (the sperm and eggs require a VERY wet environment).
Animals in the sea can release cells into the sea. There was no reason not to until it became required.
Wiki User
∙ 9y agoThe echidna does not fertilise externally. It is a mammal, albeit an egg-laying mammal, and all mammals fertilise internally, within the reproductive organs inside the body.
Wiki User
∙ 15y agoAn echidna lays eggs because it is a monotreme, an egg-laying mammal.
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What are two groups of animals that fertilize externally?
birds and fish are 2 :)
Does a platypus fertilize internally or externally?
internally
Do grasshopper fertilize internally or externally?
internal
Do amphibians fertilize their eggs internally or externally?
Amphibians fertilize their eggs externally.
Do earthworm fertilize internally or externally?
externally
Why do animals that fertilize eggs externally produce millions of eggs?
It gives them a better chance or increases the odds of having atleast one egg fertillized.
How do poison arrow frogs reproduce?
Externally fertilize eggs.
Does the nile crocodile fertilize internally or externally?
Internal fertilization
Can sponges fertilize internally and externally depending on species?
true
Does fertilisation take place internally or externally?
That depends on the species you are asking about, mammals fertilize internally and fish externally.
Does all fertilisation take place internally?
No. Fishes fertilize externally.
Do koalas fertilise their young internally or externally?
Koalas do not fertilize their young. They fertilize each other (internally) to produce young.
