All About Sea Urchins

Today we are going to talk about Facts about Urchins. Urchins in the Echinoidea class are commonly referred to as thorny, globular animals and echinoderms. Urchins can be found in many places around the world. There are more than 200 species of this type of creature in the ocean and even in recent times Urchins have been found. So let's gather a little more information about Urchins.

Urchins are known to be an important part of the ocean ecosystem. And Urchins is unfortunately facing new dangers every day. Urchins inhabit all oceans and depths from international to 5,000. This type of species is usually 3 to 10 cm. Urchins feed mainly on algae and in addition the species eats slow-moving or sessile animals. Hunters of urchins include starfish, sea otters, wolf eels, triggerfish and humans.

Urchins belong to the larger group of animal phylum and Bilateria, and that group includes arthropods, chordates, annelids, and mollusks. A species called Urchins lives in all climates, from tropical to polar, to coastal habitats from rocky and coastal to the depth of the huddle zone.


This species is usually 3 to 10 cm in size. Urchins have a rigid and usually rounded body with walk able spines. This type of animal is archaeologically called the sea hedgehog. The lower surface of the urchins is described as "oral" and the upper surface as "aboral".

One species of Urchins is oval, including sand dollars with the front and rear ends of sea urchins and gives a degree of bilateral symmetry. In this type of animal the upper surface of the body is slightly domed but their lower side is flat and the sides are devoid of tube feet. Sea ​​urchins can be stripped by sand and other soft objects.

Life Cycle and Development

The eggs of the female species of urchins float freely in the ocean but some of their species protect them more with their spines. The eggs of urchins meet with the free-floating sperm released by the male and then within 12 hours a free swimming blastula develops in the fetus. The other few species of this type of animal have a supply of nutritious yolk and such species lack arms and therefore do not need to be fed.

Urchins change into adult form beginning with the formation of test plates in adolescence and which develop to the left of the larva. In some species of urchins, adults reach their maximum size in about five years. An arch species called juvenile matures sexually in two years and can live up to 20 years.


This type of species usually has different males and females. In addition, Urchins does not appear to have different features externally. The reproduction of urchins also includes gonads nutrient stored organs and which are made up of two main types of cells. Five gonads are found in normal urchins and which fall below the interambulacral regions of the test. Forms of irregular urchins are mostly four and have excessive gonads absent inside.

Range and Habitat

Usually this type of species is established in most seabed habitats at a fairly wide depth, from the intestinal tract to the bottom. Some species of urchins, such as Cidaris abyssicola, can live at the depths of several thousand meters. Fantastic bottle-shaped irregular urchins live only in the huddle zone and have been collected at a depth of 6850 m below the surface in the Sunda Trench.

This type of species can be found in all climates from warm seas to polar oceans. The larvae of the Sterechinus neumayeri use energy more efficiently than other organisms in the metabolic process. Despite the presence of urchins in almost all marine ecosystems, many species are found along temperate and tropical coasts.

Relation to Humans

Injuries usually caused by this type of species are puncture wounds inflicted by the brittle, fragile spine of urchins. Urchins are a common source of injury to marine swimmers. Their bites vary in severity depending on the urchins. Urchins’ spinal cord can be toxic and can cause infections. This species can be used in many parts of the world as a culinary delicacy and is commonly called sea urchin roe.


This species usually lives in warm waters on rocky bottoms and near coral reefs. Sea pollution and overfishing are major threats to the survival of the Urchins species. Due to the sharp decline in the number of Urchins species in the wild, it is placed on the endangered species list.

Hundreds of small feet are commonly found in this species. The species Urchins has 5 pairs of rows of tubular small legs and is called pedicellariae. These small legs of urchins are located between the spines. Each leg of the urchins is a small sucker in shape. The feet of this species are also useful suckers to help catch food and attach them to the sea floor.

Urchins have been known to exist since 2004, and brightly colored Urchins were observed when a group of emerging shell collectors discussed them online.

It is possible for some fish to develop immunity to the venom of the urchin species. Clownfish are the only species of fish that deliberately try to build up immunity to the venom of urchins.

Urchins have zero bones in their body. Unlike humans, urchins do not rely on bone formation to support their bodies. This type of species has a shell-like structure called a "test". The formation of urchins consists of small plate segments that enclose this species. In addition, the "test" urchins have spines that help the urchins protect themselves from predators.

In the wild, sea urchins can live up to 200 years. The oldest living species of the sea was the red sea urchin and its date is about 200 years old. The lifespan of Urchins in captivity is reduced to only 30 years. This species has been able to live a long life in the past but changing sea conditions have made it difficult for them to survive. Urchins make up a large percentage of the ocean's diet.

Urchins form the shell of its bone plates and provide protection to the soft inner parts. And the body of this type of species has radial symmetry.

The color of urchins depends on its different species. Most Urchins are black, purple, brown, red and green. And some species of urchins have claw-like structures on the body surface. And this composition is used for storage of food and removal of substances attached to the body.

The main enemies of this species are fish, otters, seabirds, crabs, sunflowers and humans.

In the spring, you have the mating season of Urchins. In addition, like many other sea creatures, this species reproduces by releasing eggs and sperm cells into the water.

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