Sea urchin-diadem: a nightmare of a tourist and diver (7 photos)

Best defense is attack. This is probably what the diadem sea urchin thought somehow, turning his body into a palisade of needles several times longer than his body!





My attempts to make peace with an angry girl look something like this:

Black, white or striped spears rush 20-30 cm in all directions. Such a defensive structure automatically turns the territory where the echinoderm has settled into the hedgehog’s personal space. So be careful on shallow beaches, rocky coastlines and coral reefs of the Pacific and Indian Oceans - this is where our introvert lives.



If the word “departed” had a material embodiment.

In addition to the fact that the needles are sharp and easily break off, they are also poisonous. Although not enough to kill a large animal, there is little pleasure in being pricked by a giant thorn.





17th century, battle of pikemen, oil on canvas.

The only thing visible through the barrier of thorns is something that looks like an “eye.” Only through this “peephole” undigested remains and waste products are thrown out of the hedgehog. Organs such as the mouth and the nerve ring, which replaces the brain, are located below in animals.



You've been noticed... Or not.

The rear-up position does not interfere too much with the echinoderm in its daily routine. With the help of overgrown bristles, urchins stride sedately among the rocks and corals, fulfilling their main ecological responsibility - monitoring the amount of algae on the reefs. Despite the unsociability, this is a socially important matter - in the absence of echinoderms, algae grow beyond measure, which does not have a very good effect on the fragile ecosystem of coral reefs. The hedgehog does the job carefully, not sparing his stomach. He has nowhere to rush - no one in their right mind would climb the peaks.



*when I came to ask my boss for a salary increase*

The only one who is able to get through the defense is the triggerfish fish. With powerful jaws, she literally gnaws her way to the soft carcass of the diadem. If the hedgehog realizes that a gap has formed in the barrier of stakes, it groups up and turns into a tumbleweed, rolling away from danger. Hedgehogs do the same thing when they finish their night shift - they roll into small crevices and cracks, where they burrow until the next night.



- Hey! Hey, it's my defense, not yours! Well, shoot!

The desire for seclusion also affected reproduction. A couple of hedgehogs may have some difficulties if they decide to get close, so the animals have developed a method of contactless fertilization! When the water reaches a comfortable temperature, the hermits cluster in a relatively dense group and release sperm and eggs into the water in huge quantities. Maybe they'll meet there somehow.



During the breeding season of these hedgehogs, the bottom turns into a minefield!

Deprived of parental care, the larvae float with the current for several months, feeding on smaller plant plankton. But this is not the most severe test: in the process of growing up, lycinus will not only have to grow, but change the type of symmetry. They divide their body from two parts into five! Moreover, the final transformation takes only a few hours - the young urchin becomes spherical and descends to the seabed to scrape algae and isolate itself from the whole world!