Fish
How they reproduce
The reproductive strategy of fish is fairly simple, but, don't underestimate its effectiveness - remember fish have been around far longer than mammal, birds and reptiles. The fish has a simple but effective reproductive strategy.
Different species have different specific techniques, but here is a general overview of what fish do.
There is is often a simple courtship, maybe a dance, that allows the female to chose a mate. She may fan some of the ground to make a relatively soft spot on which to lay her eggs (or spawn).
She then lays her eggs. The male immediately swims over the same spot and releases his sperm. This means that fertilisation is external. This is not very efficient and huge numbers of gametes are wasted. Luckily they are produced in huge numbers.
Here you can see it happening - there is really no need to watch this for 4 minutes.
Different species have different specific techniques, but here is a general overview of what fish do.
There is is often a simple courtship, maybe a dance, that allows the female to chose a mate. She may fan some of the ground to make a relatively soft spot on which to lay her eggs (or spawn).
She then lays her eggs. The male immediately swims over the same spot and releases his sperm. This means that fertilisation is external. This is not very efficient and huge numbers of gametes are wasted. Luckily they are produced in huge numbers.
Here you can see it happening - there is really no need to watch this for 4 minutes.
Once the eggs are fertilised the parents play only a very small role, if any. At best the the parents may guard the nest for a few days. The male stickleback is an exception. He will guard the nest for weeks and will even fan the eggs to provide them with extra oxygen.
The young are born very vulnerable to predators and many are killed very early in their life. Again, because they are produced in large numbers it is not too much of a problem.
In summary, fish play a numbers game. The chances of their young surviving are one in several thousand. So they produce several thousand eggs and the chances are one will survive. Job done.
The young are born very vulnerable to predators and many are killed very early in their life. Again, because they are produced in large numbers it is not too much of a problem.
In summary, fish play a numbers game. The chances of their young surviving are one in several thousand. So they produce several thousand eggs and the chances are one will survive. Job done.
Advantages and Disadvantages
AdvantagesAsexual reproduction: Gives rise to variation.
Lots of offspring: Lots of variation Most will find a mate: Lots of variation. No energy used nurturing or feeding young. Lots of offspring, good chance one will survive. |
DisadvantagesHigh waste of gametes. Waste of energy.
Very high mortality rate of offspring. |