Exploring the World of Sea Urchins: Types, Gender, and Seasonality

When it comes to ocean delicacies, sea urchins, or "Uni" as they're known in Japan, hold a special place on the menu. Uni enthusiasts often indulge in this ocean treasure as a culinary highlight.

Yet, there are those who remain uncertain about the unique flavors of Uni. What sets this Japanese delicacy apart, and what's the secret to unlocking its full potential? Let's dive into the fascinating world of sea urchins.

Types of Sea Urchins

In Japan, you'll commonly encounter two main types of sea urchins: "Bafun Uni" and "Murasaki Uni." The key to distinguishing them lies in the length of their spines. "Bafun Uni" boasts shorter spines, while "Murasaki Uni" proudly showcases longer ones.


Bafun Uni

Murasaki Uni


Male (♂) and Female (♀) Sea Urchins

Sea urchins, like many creatures, come in both male and female varieties. However, telling them apart through visual cues alone can be tricky. But don't worry; there's a way. Gender becomes evident when you examine the color of their roe, which is essentially their reproductive organs.

Sea Urchin Seasonality

While you can find fresh sea urchin throughout the year, the pinnacle of flavor often occurs just before the spawning season. For those in pursuit of the finest Uni, Hokkaido is the ultimate destination. The sea urchin season in Hokkaido commences around January, beginning in the Nemuro area and circling counterclockwise around Hokkaido. It reaches its zenith around August in places like Otaru, Shakotan, and Urakawa, where the sea urchins grow to their largest size.


Selecting the Perfect Saltwater Sea Urchin

When you embark on the quest for saltwater sea urchin, here are two vital checkpoints to consider:

  1. Clarity of the Immersion "Saltwater": Clear saltwater indicates freshness. Over time, sea urchins tend to liquefy, causing the saltwater to lose its transparency.

  2. Integrity of the Sea Urchin Pieces: Opt for sea urchin pieces that remain intact and firm rather than those that have become loose. Sea urchins can lose their individuality as they dissolve over time.


By the way, the part of the sea urchin we relish as a delicacy is its roe, or gonads. You can distinguish between male and female sea urchins by the color of these gonads. Females exhibit a light yellow to orange hue, while males sport a reddish to dark brown color. In the market, the paler-colored female sea urchins tend to command greater esteem, emphasizing the value that females hold in the realm of sea urchins.

The next time you find yourself indulging in Uni at your preferred sushi restaurant, you'll possess a deeper understanding of the intricacies behind this ocean delicacy. Remember, Uni isn't just about taste; it's a harmonious blend of science, tradition, and nature's bounty, captivating the palates of seafood enthusiasts worldwide.