See sea urchins turned upside down from the inside out to ... be reborn

Sea urchin is a class of organisms belonging to the Multi-spiny animal industry, present in most oceans around the world.

In appearance, sea urchins in adult stage have a diameter of about 3-10 cm, about 3-4 cm thick. As the name implies, the entire surface of this creature is surrounded by sharp spines, when an organism is accidentally pierced by this defense layer, it will immediately hurt in the injured skin. However, this wound usually does not affect too much health.

Sea urchins are found in most oceans around the world.

Sea urchins can be compared to an empty spiny ball, because the volume of meat inside is very small compared to their overall shell mass. The fibers are yellow or orange, sticking along the shell and having a 5-8 star-like texture.

Besides the odd shape, the way of reproduction and development of this animal is also very special, because they possess the technique of 'turning from the inside out to regenerating'.

Specifically, during the breeding season (Spring), male sea urchins will release a huge amount of sperm into the ocean, while female sea urchins do the same with eggs. However, only a small part of these eggs and sperm can meet to fertilize the vast seabed.

Once the eggs are fertilized, they will develop and hatch sea urchin embryos. From the moment of hatching, sea urchin embryos have been able to swim, growing a bit more porcupine embryos become larval form, shaped like an umbrella. Interestingly, porcupine larvae are completely blind and deaf , though they continue to swim for weeks and months in this state and survive by eating algae.

At a certain point, the larvae are forced to find a surface to land on.

While traveling around the ocean, an adult sea urchin, now at a microscopic size, gradually forms and grows right inside the larvae. At a certain point, the larvae are forced to find a surface to land on, before the mature sea urchin becomes too large. When the time is almost ripe, the current will bring the larvae close to the coast, right where the waves hit the white foam. This wave disturbance combined with the delicious smell of kelp makes the larvae know that the time has come.

At this time, the larvae will stop swimming and drop freely into the sea floor. The next development is actually the strangest thing in the whole development process. Accordingly, from within the larva, the tube legs begin to protrude. These pioneering legs will carry out the task of pulling the entire mature sea urchin inside out, just like the way we flip a sock. At this time, sea urchins have officially transformed into adult form .

Discover the unique sea urchin breeding and growth method in the video below:

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