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Why Your Sea Urchin Is Losing Spines!

Sea urchins, also known as Echinoidea, are spherical, glossy animals that live in the seas and oceans.

They are most recognized for the long, thin spines, also known as celia, that cover their body like porcupine needles. These spines defend them from predators nearby.

In the conventional sense, sea urchins lack what is known as an eye. Their whole body functions as a compound eye, allowing them to navigate by utilizing information from ambient light levels.

In this guide, we will cover the basics of the sea urchin before going into more detail about their spines as they are the most notable characteristics of a sea urchin that provides them with much-needed protection.

However, what happens when these important spines start to fall out, and what can you do to stop it? 

What Do Sea Urchins Eat?

Sea urchins are herbivores that feed on algae, barnacles, and other slow-moving organisms.

It’s worth noting that sea urchins play an essential role in preventing algal overgrowth in locations like coral reefs.

Sea urchins may be found in both warm and cold seawater bodies, at varying depths.

Sea Urchin Losing Spines

Can Sea Urchins Sting You?

Sea urchins will not harm you, but because they dwell in shallow water and tend to hide among rocks, you may accidentally tread on or touch one.

If you softly touch a sea urchin, you will most likely not get stung; but, if you make contact with any amount of pressure, such as stepping on a sea urchin, the sea urchins spines will most likely sting you by releasing venom.

Sea urchin stings are seldom deadly, although they are extremely harmful. You should be informed of the signs and remedies so that you can seek expert assistance if necessary.

If you are stung, your symptoms will vary depending on which of the many sea urchins stung you. Some symptoms of being stung by a sea urchin include redness and swelling around the area that was stung.

You may also experience aching muscles and infection if you do not seek treatment. 

The most crucial thing you can do is remove the spine and pedicellariae as soon as possible. If you can’t pull the spine out on your own, you’ll need to see your doctor.

Depending on how far into your skin the spine has penetrated, they will either make a minor incision or undertake surgery to remove it.

What Causes A Sea Urchin To Lose Its Spines?

What Causes A Sea Urchin To Lose Its Spines?

If you have a sea urchin as a pet, make sure the water has enough salt since sea urchins cannot grow in freshwater.

Aquariums with sea urchins require the tank water to be cleaned and changed on a regular basis. Contaminants will collect if you just “fill up” the water, potentially influencing the pH levels of the tank.

Stirring the sand in your tank should be done with caution, as it may result in poor water quality due to detritus and other particles entering the water column.

Also, if you’re doing a water change, make sure the water is introduced gradually over a few days rather than being thrown in all at once. The sand bed will not be disturbed as a result of this.

This also applies to tanks that do not have a bottom. Detritus builds up behind the rock work and is easily expelled into the water column.

Because these creatures can only survive in environments with a pH of six to nine, a change in pH would result in the loss of their spines.

One of the most prevalent causes of a sea urchin losing its spines is starvation.

If the environment is devoid of algae or small invertebrates that sea urchins may feed on, they are prone to lose their spines due to hunger.

Environmental stress, acclimation shock, a lack of food, and high nitrate levels over 10 p.m. are among the primary causes of sea urchin death.

Once they begin to lose their spines, they become prone to bacterial infections, which are difficult to treat.

What Causes A Sea Urchin To Die?

The death of a sea urchin can be caused by a multitude of circumstances, much like the death of any other living creature on the planet. Here are some of the factors that might lead to sea urchin mortality.

Predators have a considerable influence on sea urchin populations, which cannot be denied.

Sea urchins can be eaten by large populations of marine species ranging from shellfish such as crabs and lobsters to sea otters. Predators include eels and fish such as wrasse and triggerfish.

As previously stated, sea urchins flourish in certain environmental circumstances. Most sea urchins will die if the pH or salinity of a body of water changes.

Furthermore, contaminated water might be harmful to sea urchin health and limit its lifespan.

Some illnesses, such as Bald Sea Urchin disease, propagate across marine urchin populations, causing the spines to fall off the sea animals.

This early “balding” makes it more difficult for them to ward off predators, making them easy prey.

How To Tell When A Sea Urchin Is Dead

Because of its unusual appearance, it is usually difficult to tell whether a sea urchin is dead or alive. The most noticeable characteristic of a dead sea urchin is that its spines have fallen off.

It is also worth mentioning that sea urchins that have lost their spines are usually hollow on the inside, indicating that they have died.

Any sea urchin that still has some of its spines intact has a fair chance of survival. If you come upon a sea urchin-like this on the beach, gently scoop it up and return it to the water using a shovel.

It may surprise you to discover that sea urchins may live between 15 and 200 years. 

These one-of-a-kind aquatic invertebrates may survive for a long time if they are in good health and have suitable environmental conditions.


Sadly, if the sea urchin is already losing a significant number of spines, its prospects are not promising. If they just lose a few spines, they have a fair chance of recovering and living to be 2 to 5 years old. 

There are many things that can cause sea urchins’ spines to fall out and make them bald but once you know what these causes are, you can put in the steps to prevent them from happening.

Thus, keeping your sea urchin nice and happy for many years to come!