There are estimated to be 950 species of sea urchins, which are part of a broader group of sea creatures that include starfish, brittle stars, sea urchins, and sea cucumbers. All sea urchins are edible; however, some have a higher toxin concentration in their spines than others.
There are two things to look for when assessing sea urchin edibility. The first is to look at the color, and if it is green, grey, red, pale yellow, or purple, it’s edible; the second is to look out for small bits of seaweed, shells, or rocks that are attached to the top which is an indication that they are edible.
Sea urchins move slowly, crawling with tube feet and propelling themselves with their spines. The spines are attached to ball-and-socket joints and can point in any direction. The internal organs are enclosed in a hard shell, and the reproductive organs within the shell are edible.
How Do You Know If A Sea Urchin Is Edible?
The question of sea urchins being edible needs to be answered in two parts.
The Sea Urchin “Meat”
There is often confusion concerning whether sea urchins are edible or not.
Most sea urchins are edible; however, like oysters, their flavor varies between species, the areas they inhabit, and the sea urchins’ diet.
The following are ways to evaluate sea urchins and how edible they are.
Edible Sea Urchin Color
Sea urchins, which are green, grey, red, pale yellow, and purple, attract the highest global demand.
The most which attracts the highest value is the grey sea urchin (Strongylocentrotus intermedius). This species is found in the Far Eastern Russian regions of Primorye, South Sakhalin. It is also native to the Kuril Islands, northern Japanese islands, and the Korean Peninsula.
Toxic Sea Urchins Color
The sea urchins identified as toxic are only dangerous if the spines penetrate the victim’s skin. It does not refer to the edible parts of sea urchins.
The pinkish-white to yellowish-white flower urchin (Toxopneustes pileolus) species is considered to have the most toxic sting from its spines. These sea urchins are commonly found in coral reefs and seagrass beds. The species are also found in rocky or sandy environments and can survive to a depth of 295 ft (90 m)
The dark black sea urchin species should be avoided.
The Sea Urchin Spines
The spines that protrude from the sea urchin’s body may be toxic.
This injury occurs only when the urchins have stepped on accidentally or handled incorrectly or carelessly.
Victims who have envenomated when a spine penetrates soft tissue may experience one or more symptoms.
- Pain at the site of the envenomation
- Abdominal pain.
- Nausea.
- Vomiting.
- Paresthesia (burning or prickling sensation.)
- Weakness.
- Syncope (fainting or losing consciousness).
- Hypotension (low blood pressure).
- Respiratory distress.
- Tenosynovitis (inflammation of a tendon.)
- Granulomas (A small area of inflammation.)
The consequences are rarely fatal; however, there have been recorded cases, one of which involved a Japanese diver. It is thought the envenomation caused the diver to lose consciousness which resulted in his drowning.
The most dangerous of the sea urchin species is the flower sea urchin (Toxopneustes pileolus). The poison from this sea urchin species’ spines causes severe symptoms, including severe pain, respiratory problems, and even paralysis.
What Do Sea Urchins Taste Like?
Sea urchins are considered a delicacy, particularly in sushi, where they are called by their Japanese name – Uni.
Only a small part of the sea urchins are edible, namely the gonads.
A fully grown sea urchin has a fivefold symmetry of sexual organs inside. These are ready to be eaten.
Eating sea urchins provides an interesting taste experience with three stages of flavor.
- The first flavor reminds the diner of a good quality melted Bree cheese.
- The second flavor that follows will remind you of a delicious, sweet custard.
- The final taste is not easily described, but it has been described as being like an oyster which is essentially the same taste as the ocean. It plays with your taste buds reminding you of long lazy days at the ocean and wonderful memories of swimming in the waves with family and friends.
One of the main attractions of sea urchins to discerning diners is the melt-in-your-mouth buttery texture. The texture of the meat differs slightly between male and female sea urchins, with the meat from males having a smoother texture than females.
What Is In A Sea Urchin?
The sea urchin’s structure is very simple.
From the front of the body is a mouth with a fascinating jaw structure called “Aristotle’s Lantern.” Muscles are set inside the structure to make the jaw work.
The mouth joins with the coils of the intestinal tract.
The water vascular system helps move the tubed feet and helps move the spines.
The last part is the reproductive organs, ovaries, or testes, depending on the sex. These vary in size depending on what part of the reproductive cycle is active. If the sea urchin is mature, the testes should be in a fivefold symmetry.
The reproductive organs are called “uni,” In the world, sushi is considered a delicacy, which is why sea urchins are harvested for food.
The sea urchin’s sexual organs (Uni) are the only part that can be eaten.
How Do You Prepare, Serve And Eat Sea Urchins?
Before you handle the sea urchin, put on a pair of strong gloves. This will protect your hands from the sea urchin’s sharp spines.
Work around a sink because as you prepare the urchin, the spines will start to fall off, and you will need to keep them isolated.
- Place the sea urchin upside down on a plate.
- Using a pair of sharp scissors, cut around the base of the sea urchin.
- Lift the part you have cut to expose the urchin’s innards.
- Drain all the dark liquid and seawater from the urchin into the sink.
- You will now see the 5 orange, tongue-like structures, which are the sea urchins’ sexual organs.
- Extract the 5 structures and place them in a bowl of salt water.
- Rinse them off to remove any of the brown residues left from the liquid you drained.
- Place the bowl in a cold fridge to keep them chilled and ready for eating.
If the organs are brown, the sea urchin has gone off and is not fit for eating.
The sexual organs are the only edible part of the sea urchin, so do not be tempted to eat anything else.
Conclusion
All sea urchins are edible; however, certain species are sought after by diners around the world. The most popular sea urchins are green, grey, red, pale yellow, or purple.
The spines are, however, toxic, and it is these that you must be careful of.
References
- https://www.sciencedirect.com/science/article/abs/pii/S0167930907800652
- https://en.wikipedia.org/wiki/Sea_urchin
