8 Animals that Practice External Fertilization

When you dive into the ocean along coral reefs and they are beautiful with full of color and life. However, have you ever wondered how these animals find a mate when they don’t move at all?

They find a mate and reproduce by releasing eggs and sperm into the water. They do this so that the cells will find each other and the eggs will be fertilized.

This method of fertilization is commonly done by aquatic animals. This method is called external fertilization, as it happens outside the body. This process sometimes is called spawning.

Are you curious of the animals which practice this method of fertilization? Here they are, the 6 animals that practice external fertilization.

  • Grunions

Grunions are species of fish that practice external fertilization. They swim on to the shore and mate in the sand. Then, the females bury their tails in the sand and lay their eggs there. After that, the male wraps around her and fertilizes the eggs the female lays.

  • Salmon

Salmon fish is also practicing external fertilization. The male and female salmon fish leave the ocean at the same time. Then, they swim for miles and miles up river together.

They gather in a specialized spot to do the fertilization called spawning spot. The females then make nests in river beds and fill them with eggs. Then, the males release sperm over these nests. Salmon fish love to migrate. Read more about it in salmon migration.

  • Sea Urchins

Sea urchins are one of the sea creatures that can sting. Sea urchins inhabit tide pools or reefs. Due to this fact, there’s a risk that all of their gametes getting washed away and as a result there might not be any fertilization happening.

However, they have several methods to prevent it. They synchronize their spawning so that there won’t be enough time for the eggs and sperms to drift away and be diluted.

There’s also a process called chemotaxis where they help attract the sperm towards the eggs.

  • Starfish

Starfish don’t release their gametes and just wait them to be fertilized. Instead, they have a method where they synchronize their spawning so that the chances of fertilization increases.

To do this, they gather in groups on certain days and at certain times. The length of the day and the amount of light are used as indicators that the other members are ready to spawn.

  • Frog

Frog is another animal that practices external fertilization. The females and males will release eggs and sperms near each other so that the chance of the eggs to be fertilized is bigger. In most frogs, however, the male will hug the female’s back and fertilize the eggs as she lays them.

During rainy season, the females will lay hundreds of eggs in water. The males then release sperms as well. These sperms swim in water and reach the eggs and finally fertilized them.

Do you know that some frogs are poisonous? Make sure you avoid these poisonous frogs in the world! They may look cute, but they are deadly dangerous!

  • Corals

Corals depend on the motion of the water to do external fertilization. The eggs and sperms are released around so that they meet by chance. It may sound a bit unlikely, but it does happens.

To help make sure these eggs and sperm will meet and find one another, there are thousands or even millions of eggs and sperms are released. By doing so, the chance of them finding one another is greater and higher.

  • Sea Anemone

Sea anemones, also called flowers of the sea, can be found in oceans all over the world. They are colorful sea creatures which also practice external fertilization.

Most anemones reproduce asexually through budding, where the fragments break off and develop into new individuals. Some fragments stretch themselves along their base and split across the middle. As a result, two new anemones of equal size are formed.

  • Salamander

Some salamanders practice internal fertilization, but most of them are also practicing external fertilization. Most salamanders reproduce by laying round eggs coated with a protective, jelly-like material. Each species could have different number of eggs, ranging from 20 to 500 eggs in one cluster.

The eggs are both aquatic and some land-dwelling species are laid underwater in chambers, upon vegetation or under stones. Then, the male spreads his semen directly over the eggs after they have been laid.

Get to know the other facts about animals by reading animals that hibernate during summer and animals that migrate during winter.