Do Sea Urchins Feel Pain? What Science Says!

Animals without a backbone are scientifically classified as invertebrates. Sea Urchins are invertebrates and are also known as echinoderms. Since they lack backbones, it’s not exactly clear whether they feel pain like humans. 

So, do sea urchins feel pain?

The scientific evidence available so far shows that sea urchins do not feel pain, at least not like humans. And that is because they lack pain receptors and a centralized brain. 

Do Sea Urchins Feel Pain

How is Pain Identified in Animals?

Although pain has a lot of definitions, it is said to be the ability of an organism to perceive and reflexively respond to harmful stimuli by moving away from it. Pain can be either “physical” or “emotional.” 

In most animals, pain is usually difficult to identify. But in humans, it is often connected to physiological and behavioral patterns and facial expressions. 

In general, animals in pain tend to show a lot of aggression which sometimes results in vocalization, showing distress, and touching the area affected. They may also learn to move away from the source. 

For instance, in humans, when we place our palms on a hot surface, we immediately react by removing our hands. Once we identify the hotness, we tend not to place our hands on the same spot. 

The pain experience may also be accompanied by rapid breathing and increased pulse and blood pressure. 

How Do Shellfish Process Pain?

The term “shellfish” is used to describe all aquatic invertebrates that have a shell, such as shrimps, lobsters, crabs, clams, oysters, etc. Although all shellfish have a nervous system, not all of them process pain. For example, oysters do not feel pain.

On the other hand, there’s evidence to suggest that crabs, lobsters, and prawns may feel pain. 

To feel pain, there are two main processes involved. 

The first process is nociception. Here, the shellfish is exposed to a noxious stimulus, which facilitates a reflex response, causing the animal to move away from the stimulus. 

The second process is “pain.” In this process, the internal systems interpret the stimuli which the animal just experienced, thereby facilitating the painful sensation felt. It is important to understand that the kind of pain described in this context is “physical pain.” There is also no certainty that all shellfish feel emotional pain.

Can Sea Urchins Feel Pain?

Sea urchins do not feel pain, at least not like humans. Their inability to process pain can be attributed to their lack of nociceptors. 

Many studies also suggest that sea urchins lack the brain mechanisms needed to experience pain in the same way as animals with more sophisticated neurological systems.

Having said that, they have numerous sensory cells scattered across different parts of their body. These sensory cells are responsible for their sensitivity to light, water currents, chemicals, and touch.

Do sea urchins feel pain when you eat them?

As mentioned earlier, sea urchins do not feel pain, and this applies even when you eat them. As a matter of fact, most invertebrate seafood do not feel pain when you eat them. 

Most seafood eaten by humans are usually served cooked, which means they are lifeless. 

However, some sea urchins are usually served uncooked – they too don’t feel pain when you eat them.

Do sea urchins feel pain when they die?

Sea urchins don’t feel pain when they die. Once a sea urchin passes away, all of its spines disappear, leaving only its test. The residual test usually has small lumps where the spines were linked if you look at it closely. This is an absolutely painless process.

Do Sea Urchins feel more pain than humans?

Sea urchins do not feel more pain than humans. Compared to humans, sea urchins have a less sophisticated neurological system, making them unable to interpret pain the way humans do. 

Urchins could react to other stimuli like light, touch, and toxic chemicals by moving their spines away, but these reactions are solely reflexive and do not interpret pain.

On the other hand, humans have nociceptors spread across different parts of their body to detect pain. Although the severity of the pain may vary depending on the stimulus, it is obvious humans likely feel pain more than sea urchins. 

Do Sea Urchins Have a Brain?

Anatomically, sea urchins do not have a brain. However, they have a neural center, which is a large ring of nerves encircling their mouth. This nerve ring performs a similar function as the brain in other animals – it connects all other nerves from the sensory system. 

In addition, the nerve ring in sea urchins branches to form numerous nerves which innervate the spines, pedicellariae, and tube feet.

Do Sea Urchins Have a Nervous System?

Yes, sea urchins have a simple nervous system that branches from their neural center (nerve ring) and forms finer nerves, which are scattered across the body. They are present in their tube feet, pedicellariae, and spine. 

With the help of their nervous system, sea urchins are able to respond to light, temperature, touch, and chemicals. 

How to Care for Sea Urchins?

Most urchins usually can’t tolerate poor water quality or water bodies with high nitrate levels. It is very important to take care of them if you wish to keep them away from their natural habitat. 

Maintain good water quality

To care for your urchins, always observe the water temperature, salinity, and specific gravity. In addition, ensure the aquarium is copper-free, as copper is toxic to sea urchins.

Feed them well and on time

It’s also important you feed the urchins well. Urchins are omnivores; they usually prey on algae and detritus. If you own an established aquarium, urchins will likely feed on the algae present in the aquarium. 

On the other hand, if you own an aquarium without algae, you might need to add dry seaweeds to the aquarium to ensure your urchins’ survival.

Do Sea Urchins Feel Pain

Keep separate from aggressive fishes

Lastly, when breeding urchins, avoid pairing them with other aggressive aquatic animals. Animals like parrotfish, triggerfish, and starfish should not be bred in the same tank with urchins. Starfishes will likely prey on them. 

Other Related Questions About Pain In Sea Urchins 

Is sea urchin a living thing?

Yes, sea urchins are living things. They are marine invertebrates that belong to the phylum Echinodermata; hence, they are often referred to as echinoderms. Etymologically, the word “sea urchin” translates to “regular echinoid.” Other organisms you will find in this phylum include sand dollar, sea cucumbers, brittle stars, and so on. 

Can vegans eat sea urchins?

Technically, yes, but only if the person doesn’t want to be a vegan anymore. Sea urchins are animals and shellfish, which makes them non-vegan. Vegans are people who do not eat or use any animal products. 

Do sea urchins have consciousness?

It is unclear whether sea urchins have consciousness. While some scientists argue that their behavior indicates some level of awareness, others believe they are merely reacting to stimuli in an instinctive, reflexive manner. 

Conclusion: Do sea urchins feel pain?

To sum up, sea urchins don’t technically feel pain like humans. This is because they lack nociceptors and a centralized brain. Having said that, they are able to react to changes in their environment – thanks to their network of nerves and sensory cells. 

In general, the topic of pain sensation in shellfish is still a subject of debate in the scientific community, and more research is still being carried out in the area. 

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