Sea Urchin is a seafood species surrounded by mystique and, at times, misunderstanding. If your first taste of Urchin is stepping on one in a rock pool, you’d be forgiven for being hesitant to eat one; their sharp spines intimidate even the most adventurous diners!
This week we are diving deep into Sea Urchin on our social media, to demystify this wonderful species and empower you to eat more of it. Today, we bring you the basics; read on to learn all about Sea Urchin.
Biology
Sea urchins are spiny, ancient organisms, classified as Echinoidea. About 950 species of sea urchin exist around the world, living on the seabed of every ocean and inhabiting every depth zone – from the intertidal seashore down to 5,000 metres!
Inside their spiky, spherical outer shell, they have a mouth, gut tube, a primitive nervous system, and five delicate tongues of gonads, which is the edible part (commonly known as roe or uni). The gonads function as both the reproductive organs and as nutrient storage.
Environmental Impact
As climate change continues to warm ocean waters, this has increased the southern range of Purple Sea Urchin, which now extends in oversupply through Southern NSW, Victoria, and Tasmania. When overpopulated, swarms of sea urchin will consume all living flora from the sea floor. This removes all habitat that juvenile fish, abalone, rock lobsters, molluscs, and bivalves would otherwise call home. These areas become what are known as barrens, and can take generations to recover. Currently, the government pays for an eradication program. We recommend consumption!
Types of Urchin 
Australia commercially harvests three species of Sea Urchin: Longspined, Red, and Shortspined. We also formerly gathered a fourth species, called the Lamington Urchin, but they are no longer commercially harvested from the wild due to low numbers.
Longspined Sea Urchin (also known as the Purple Urchin) makes up the majority of Australia's commercial catch, and is therefore the one you will see most often for sale at Sydney Fish Market. They are located along the southeast coast of Australia, from NSW to Tasmania, and reach their peak season in autumn.
Red Sea Urchin is harvested from southern Queensland to southern NSW, and is at its best in late spring to early summer.
The final type of sea urchin, the Shortspined Sea Urchin, which is known interchangeably as the green or white (and sometimes, confusingly, purple), is located in similar areas to the purple, and are in their best eating form in spring.
Harvesting
Sea Urchin are predominantly harvested by hand by divers, who often harvest other rock-dwelling species like Abalone at the same time. Some commercial divers maintain physical fitness by alternating diving or hookah days with snorkeling, even though they're usually more than fit enough. Some urchin are caught to be processed on shore, before being sold as a cleaned product. Some divers even take orders from their chefs over the phone on the way to the boat ramp, and only catch what they know can be traded live that day.
Reef areas rich in biodiversity produce the best urchin. Abundant feed, in the form of the right-coloured kelp, is imperative. Experienced divers identify which individual urchins ate most of the best kelp the night before, as this will increase the volume of the roe by as much as 100%, and be solely responsible for the naturally variable quality of the roe.
Many divers are also licensed to harvest a variety of companion species such as abalone, turban shell, and periwinkles - and it is no coincidence that these species work together wonderfully in the kitchen!
Purchasing
Whole urchin is always sold live, either from tanks or in damp buckets. Buying them this way is the cheapest option, usually only setting you back around $5-8 a pop! They are extremely easy to open at home – all you need are two tablespoons and a bit of elbow grease. Alex shows you how in .
If buying them spines and all gives you the heebie jeebies, don't worry! There are a huge range of pre-processed roe products available in Australia. Many are available at Sydney Fish Market, but gives a good overview of the different products if you want to check them out in advance.
Eating Qualities
Sea Urchin each have five fat tongues of roe in the shell, that vary in colour from off-white to a vivid ochre. The roe tastes creamy and sweet, with just enough salt or umami flavour to remind you that it's seafood.
The flavour of urchin can sometimes be impacted by which stage of the reproductive cycle it is at, the water temperature, and what kind of food it has been consuming, so it is always best to buy urchin in its peak season to enjoy it at its best.
If you want to learn how to cook with Urchin, Sydney Seafood School have a dedicated on their schedule, which allows you to get hands on with this decadent species.