Why Sea Urchin Is So Expensive?

Sea urchin, often referred to as "uni" in culinary circles, is a delicacy that's both rare and highly sought after. In this article, you'll discover why this marine treat comes with a hefty price tag, and why food aficionados all over the world are so enamored with its unique taste and texture

Why Sea Urchin Is So Expensive?
Photo by Portuguese Gravity / Unsplash

Sea urchins are spiny, globe-like creatures that roam the ocean floors. Hidden beneath those spines is a soft, edible part called the gonad, which is what you're indulging in when you savor uni at a high-end omakase or kaiseki restaurant. It's this gonad, or uni, that people pay top dollar for, cherishing its unique taste and texture in the most refined culinary settings.

What is Sea Urchin?

Sea urchins, known scientifically as Echinoidia and belonging to the Phylum Echinodermata, are marine creatures that thrive in rocky underwater regions, especially in depths ranging from just below the low tide mark to approximately 90 meters (300 feet).

In the culinary world, these urchins are often termed "uni" and are sought after for their delectable gonads. These gonads, besides being a culinary delight, play a reproductive role in the sea urchin's life. Particularly, the red sea urchin is among the top edible species has risen to prominence as a luxury seafood in sushi establishments in Japan and has subsequently gained fame worldwide.

What Is The Cost Of Sea Urchin?

Surprisingly, a mere 200-gram box of top-quality sea urchin gonads can set you back by over $100. In Japan, where it's especially treasured, the price for red sea urchin, also known as Bafun uni, can skyrocket to $300 in Toyosu Market auction.

red sea urchin
Red Sea Urchin - Photo by Austin Voecks / Unsplash

Why is Sea Urchin So Expensive?

Rarity and Location

Red sea urchins are primarily found in specific, often hard-to-reach parts of the Pacific Ocean surrounding Japan, from California to Alaska. Their select habitats make them less abundant and harder to harvest.

In the early 2000s, divers could gather up to 2,000 pounds of top-quality sea urchins daily. Now, they average around 500-1000 pounds. The seas have ample urchins, but dwindling kelp forests affect their marketability. This kelp decline not only impacts the value of red sea urchins but also threatens marine ecosystems.

Factors like warming waters and pollution play a role, but the surge in the purple sea urchin population after the 2013 drop in sea stars, their main predator, is crucial. These purple urchins consumed most of California's kelp forests, making it harder to find marketable red urchins. The challenge for divers isn't just finding the right spot, but also safely extracting these spiky creatures.

sea urchins on ice
Photo by Tuan Nguyen / Unsplash

Harvesting and Preservation Challenges

Uni harvesting is hands-on work. Divers must carefully gather urchins from the sea floor, often from tricky spots like between rocks. Each dive's yield is limited to what one diver can collect.

The extraction process demands exactness, ensuring that the shell is cracked precisely and the gonads are preserved in their entirety. Proper cleaning is paramount, as any leftover debris can accelerate the degradation of the gonads.

Additionally, the health of the gonads can be influenced by environmental factors, such as a kelp shortage, which serves as their primary food source. Given these intricacies, combined with the inherent uncertainties of diving expeditions, restaurants mark up sea urchin dishes to ensure that diners receive the best quality while compensating for the risks involved in sourcing.

Short Shelf Life

The essence of uni lies in its freshness. At its prime, uni boasts a vivid hue, maintaining its structured, crisscrossed appearance in its original packaging without any leakage. However, as time progresses post-harvest, uni starts to deteriorate, potentially adopting an unpalatable bitterness.

The ideal scenario sees uni promptly cleaned, chilled, and dispatched to preserve its freshness. Some handlers might resort to additives like alum to retain its firmness, but this can compromise its flavor, especially as the uni ages. Intriguingly, an urchin offers only five coveted gonads. Their fragile nature and brief shelf-life of roughly a week necessitate swift processing after harvest to capture their optimum taste and texture.

Rare Rewards: Top-Grade Urchin Yields

A compromised gonad can plummet from its pristine A-plus-plus ranking to a mere B grade, causing its value to dive to just about a quarter of its peak worth. Post-harvest, specialists sort the gonads by their distinct color palette, either vibrant yellow or orange, ensuring uniformity in each collection tray.

Every gonad then undergoes rigorous scrutiny, with workers using tweezers to clear any traces of kelp, shells, or minuscule spines. The elite A-plus-plus grade is distinguished by its radiant color, primarily derived from the delectable male urchins. These are typically destined for upscale restaurants. Yet, their occurrence is akin to finding a needle in a haystack; a standout gonad emerges only once in about every 100 urchin harvests.

High Demand, Low Supply: Sea Urchin Barrens Worsen Shortages

The global appetite, especially in high-end sushi establishments, has surged for uni. This high demand, combined with limited supply, naturally drives up prices.

Both the US and Japan face challenges with sea urchins, but from different angles. While the US contends with an overabundance of inedible sea urchins due to barren environments, Japan has its own longstanding issue. The US West Coast has witnessed a staggering 10,000% surge in purple sea urchin populations since 2014, driven by warmer waters.

These urchins, while numerous, aren't commercially viable due to their diminished roe from starvation. On the other hand, areas near Hokkaido, Japan, have been grappling with sea urchin barrens for over 80 years. Such barren zones, devoid of other marine life, spell ecological and economic trouble for both nations, affecting biodiversity and the fishing industry.

Unique Flavor Profile

The rich, buttery, and oceanic taste of red sea urchin's uni is unparalleled. When served sushi-style and dipped in shoyu with a hint of wasabi, its distinctive flavor becomes even more pronounced, making it a sought-after delicacy that justifies its premium price.

The Rarest and Priciest Urchins

Three marine culinary gems include the Mediterranean's purple urchin (Paracentrotus lividus), the Pacific's red sea urchin (Strongylocentrotus franciscanus), and the adaptable green sea urchin (Strongylocentrotus droebachiensis) from both Atlantic and Pacific waters, favored for their larger, visually pleasing lobes.

California's urchins are often characterized by a creamy, sweet flavor, a trait believed to arise from the region's sulfur-rich waters. On the flip side, Maine's uni tends to offer a bolder hue and a denser consistency.

Japan's northern island, Hokkaido, is a hotspot for premium sea urchin, thanks to the uni's preferred diet of Kombu kelp abundant in the chilly, mineral-rich waters, contrasting with the Wakame diet of other regions.

Two notable species from Hokkaido waters include the Kita Murasaki Uni and the Ezo Bafun Uni. The former is hailed as Japan's top-notch urchin with its generous size resembling a human thumb and a distinct creamy taste with a depth of sweetness. The latter, the Sea Chestnut, although slightly milder in sweetness, is prized for its creamy consistency and its resilience during transport, making it a popular choice for distribution across Japan.


If you've never tasted sea urchin, I recommend giving it a shot at least once. For some, the idea might be daunting, but the experience can be transformative. To truly appreciate its unique flavor, consider sampling it in a reputable sushi restaurant, either as nigiri, a hand roll, or sashimi. The subtle pairing with rice not only complements the urchin but also aids in handling its delicate texture.

Frequently Asked Questions

What is Sea Urchin's Natural Predator?

Crabs, lobsters, triggerfish, and wrasse count sea urchins among their favored meals. The wolf eel, native to the Northern Hemisphere, is adept at hunting them, while sea otters in places like British Columbia curb their population, ensuring ecological harmony. Despite their slow pace, sea urchins boast sharp, sometimes venomous spines as a natural defense against these threats.

Fun Facts About Sea Urchin

Crab's Unique Shield: In a brilliant move, carrier crabs use sea urchins as their protective armor, giving them a natural defense against potential threats.

Five-Part Design: Differing from the bilateral symmetry of mammals, sea urchins have a distinct edge. Their mature bodies display a five-segment symmetry, setting them apart in the marine world.

Light-Sensitive Marvels: Sea urchins may not have visible eyes, but there's a belief that their whole body can sense light changes, functioning much like a compound eye.

Built to Bounce Back: Despite the challenges of their environment, sea urchins demonstrate resilience. If a spine gets lost, they have the capability to regrow it, ensuring constant protection.

Oceanic Centenarians: Among the marine realm's long-livers, certain sea urchins, especially the red variety, can astonishingly endure for up to 200 years.

Colors of the Deep: Shattering the misconception of them being one-toned, sea urchins showcase a vibrant array of colors, from deep purples and fiery reds to tranquil greens, adding beauty to the ocean floor.

Diet and Anatomy of Sea Urchins

Sea urchins, as omnivores, primarily dine on algae but also savor marine treats like sea cucumbers, mussels, and sponges. As they navigate the seabed with their tube feet, they skillfully scoop up algae towards their mouths. Their unique chewing mechanism, the Aristotle’s lantern, consists of intricate jaws and five perpetually self-sharpening teeth, ensuring efficient consumption. If food lands on their upper surface, their tube feet relay it to their belly-located mouth. Fittingly, while they eat from below, they expel waste from their top side.

How do sea urchins move?

Sea urchins are unique marine creatures that navigate their surroundings without the ability to swim, skillfully traverse the ocean bed, favoring terrains like corals and rocks. They move using "tube feet," hydraulic appendages that help them slide across the seabed. Their signature spines do more than just intimidate; they assist in movement. Despite not having brains, sea urchins are equipped with pedicellariae - small jaw-like tools used for defense and grooming. And a noteworthy fact: some of these pedicellariae are venomous, further enriching the urchin's captivating nature.