Summary: To properly cook spider crab: use water with 60g of salt per liter (or seawater), place the spider crab upside down in cold water, bring to a boil, and cook for 18-20 minutes for 1 kg pieces, 22-25 minutes for 1.5 kg. Cool in ice water to stop the cooking. Females have more coral (roe) and are identified by a wide, triangular abdominal flap.
Exact cooking times by weight
Times are counted from when the water boils (if starting in cold water) or from when the spider crab is submerged (if starting in boiling water).
| Weight | Cold water (from boil) | Boiling water (from immersion) |
|---|---|---|
| 500-700 g | 15 minutes | 12 minutes |
| 800 g - 1 kg | 18-20 minutes | 15-17 minutes |
| 1 - 1.5 kg | 22-25 minutes | 18-20 minutes |
| 1.5 - 2 kg | 25-30 minutes | 22-25 minutes |
Practical rule: 18-20 minutes per kilo from boiling. Better to undercook than overcook — a slightly undercooked spider crab is juicier than an overcooked one.
Step-by-step guide
Step 1: Prepare the water. Fill a large pot with enough water to completely cover the spider crab. Add 60g of salt per liter (4 level tablespoons). If you have clean seawater, use it directly without additional salt.
Step 2: Place the spider crab. Put the spider crab in the pot with cold water, upside down (legs facing up). This prevents it from losing its legs during cooking — if you put it in hot water, the legs contract and can detach.
Step 3: Turn on the heat. Bring to a boil over high heat. Once it starts boiling, reduce to medium-high heat and begin timing according to the table.
Step 4: Cooking. Maintain a gentle boil for the entire cooking time. It doesn't need to boil violently — a constant bubbling is sufficient. If foam rises, remove it with a skimmer.
Step 5: Cooling. Prepare a large bowl with cold water and ice. When the time is up, remove the spider crab and submerge it in the ice water for 5-10 minutes. This stops the cooking and prevents it from overcooking.
Step 6: Rest. Remove from the ice water and place it upside down on a rack to drain any residual water. 15-20 minutes. This prevents it from being watery when opened.
Cold water or boiling water?
This is the great debate. Both methods work, but they have differences:
- Cold water (recommended): The spider crab heats gradually, the legs don't detach, and cooking is more even. This is the traditional Galician method and the safest.
- Boiling water: Faster cooking, but the thermal shock causes the legs to contract and can break. This is used when the spider crab is alive and very active (difficult to handle when cold). The final taste is practically the same.
Our recommendation: Always cold water, unless the spider crab is so lively you can't handle it (in which case, quickly put it in boiling water). For dead or less active spider crab, always cold water.
How much salt exactly
The correct ratio is 60g of salt per liter — saltier than for purging clams (30g/L) and slightly more concentrated than actual seawater (35g/L). This extra concentration compensates for dilution during cooking and seasons the spider crab meat from the outside in.
In household measurements: 4 level tablespoons of coarse salt per liter. For an 8-liter pot, you'll need about 480g of salt (half a kilo). If using seawater, do not add any salt.
Male vs. female: how to distinguish them
The difference is in the abdominal flap:
- Female: Wide, rounded, and triangular flap. Contains coral (roe) — an intense orange mass that is a delicacy. More gastronomically appreciated.
- Male: Narrow and pointed flap. More meat in the legs (they are larger), but no coral. Ideal if you prefer pure meat.
The price of female spider crab is usually 20-30% higher due to the coral. If you are looking for a complete texture and experience, choose female. If you want a quantity of meat, choose a large male.
How to open and serve spider crab
- Place the spider crab upside down. Separate the legs with a firm twist.
- Lift the abdominal flap and separate the upper shell from the body.
- Inside the shell, you will find the coral (female) and juices — this is the most flavorful part.
- Remove the gills (spongy gray parts on the sides of the body). They are not toxic but taste bad.
- With a nutcracker or the handle of a heavy knife, crack the legs to extract the meat.
- Serve the leg meat in the shell itself, mixed with the coral if it's a female.
Tips
- Upside down: Always with legs facing up in the water. If you place it face down, it loses juices and can lose legs.
- Ice water is mandatory: If you don't stop the cooking, residual heat will continue to cook the meat for another 5-10 minutes. Those extra minutes make the difference between juicy and dry.
- Drain upside down: After the ice bath, leave the spider crab upside down to drain all the water. Otherwise, it will be watery when opened.
- Optional bay leaf: Some cooks add 2-3 bay leaves to the water. Subtle but adds a pleasant aromatic nuance.
- If alive: Put it in the freezer for 20-30 minutes before cooking. It will become dormant and won't suffer when entering the water.
Season and buying
The spider crab season in Galicia and the Cantabrian Sea is from November to June, with the best time between November and March. In summer (July-October), it is protected by a closed season in most areas. Winter spider crabs have more meat and females have more coral.
When buying, choose spider crabs that feel heavy for their size — light ones are empty inside. A 1 kg spider crab should feel dense and heavy. The legs should all be intact (one without legs has been stressed and may have less meat).
For more seafood guides: seafood salad, steamed mussels, and grilled razor clams.
Conclusion
Cooking spider crab is not difficult, but the details matter: 60g of salt per liter, cold water, upside down, 18-20 minutes per kilo, and cooling in ice water. Skipping any of these steps will affect the result. The time table above is your reference — print it and stick it on the fridge for Christmas.
Frequently Asked Questions
Can frozen spider crab be cooked?
Yes. Thaw in the refrigerator 24 hours beforehand or cook it directly from frozen, adding 5 extra minutes to the cooking time. The result is slightly inferior to fresh but perfectly acceptable.
How do I know if the spider crab is full?
It should feel heavy for its size, and when you press the bottom of the flap, it should feel firm. If it sinks easily, it's empty. You can also shake it near your ear: if it sounds like liquid moving, it has little meat.
Is male or female better?
It depends: the female has coral (orange roe), which is a delicacy. The male has more meat in its legs. For a complete experience, female. For a quantity of meat, a large male.
Can it be cooked with bay leaf?
Yes, 2-3 bay leaves in the water provide a subtle aromatic nuance. Optional, but many Galicians do it.
How much spider crab per person?
An 800g - 1kg spider crab serves 2 people as a starter. As a main course, a 1kg spider crab per person or a large 1.5kg one for 2.
Can it be cooked the day before?
Yes. Cook it, cool it well, and store it whole in the refrigerator (unopened) for up to 24 hours. Take it out 30 minutes before serving so it's not too cold.
Lalo González Rodríguez
Since 1990 in Mercat del Ninot, Barcelona. We select seafood products directly from the producer. It's not marketing — there are verifiable factors.
