How Do Dungeness Crabs Mate and Reproduce?

All species have their own unique way of attracting a mate and going through the mating process to reproduce. Just like peacocks show off their tail feathers to attract the opposite sex, horses raise their tail to show off their goods, and men and women strut their stuff while paying close attention to clothes, skin, hair, and body shape. 

This is the same for Dungeness crabs; they prefer to mate in a certain habitat, choose their mates wisely, and it all comes down to the survival of the fittest. 

In this article, you will learn about each of those things along with some factors that affect the Dungeness crab population. 

The Dungeness Crab Habitat

The Dungeness crab has been commercially harvested since the 1800’s and is a common species found along the coast of California all the way up to the Gulf of Alaska and is particularly popular in the states of Oregon and Washington. 

Since adult crabs typically live and swim solo and not with a “pack” or family, they tend to find protection while burying themselves in trenches about a meter deep and don’t go out into very deep waters. They might stay close to other crabs not in their family to protect themselves from predators. Juvenile crabs, on the other hand, prefer cooler and more shallow waters than adults and hang out in plants and eelgrass (National Park Service). 

Dungeness Crab Mating

Mating occurs during the spring and summer months when females naturally molt.

When female live Dungeness crabs are ready to molt, they shed their exoskeleton to allow them to grow and develop a bigger shell; before this new, hard shell has formed is prime time for mating. The females will release pheromones, or their special chemical scent, to attempt to attract close-by males. When their scent peaks a male’s interest, he will run up on her and literally “hug” her. 

Things get a little weird after that! The male Dungeness crab “embraces” the female (sometimes willingly, other times forced) and this can last up to a few days. The female is able to see how strong and worthy her potential mate is and gets to decide whether or not he is the right partner to reproduce with. Usually, the male will carry her off into the distance to hide themselves from predators and other male crabs who probably also smell her pheromones. 

Now it’s time to get it on!

The experts at Live Science describe it perfectly--technical terms and all:

“The male transfers sperm by inserting his gonopods (sexual organs resembling antennae) into the two genital pores, called gonophores, on the female's underside. The female stores the sperm in a storage sac called a spermatheca until she is ready to use it.  Some crabs will mate standing up, facing one another, but most species actually prefer the missionary position, with the female beneath the male. Once copulation is complete, the male will guard the female for a few days (giving her shell time to harden) before taking off in search of a new mate.”

That’s it, folks! Nothing to see here…

Dungeness Crab Babies 

Baby Dungeness Crab

Now that the male has moved on, the female needs to produce her eggs and fertilize them with the stored sperm when she is ready. Typically a female Dungeness crab holds onto her eggs to incubate them for 3 to 5 months. In the meantime, she hunkers down in the sand to wait out the chilly winter weather. 

A large female can carry up to 2.5 million eggs! The number of babies that are successfully born alive depend on the weather, predators, and how many make it to the hatching stage. Once they are born, baby crabs go through 4 larval stages until they are considered an adult crab, which is the 5th stage. 

The 5 stages are:

  1. Egg Stage: They’re just chilling in their eggs, waiting to be hatched.

  2. Zoea Larva: In this stage, Dungeness crabs look similar to little shrimp and have a spine that protrudes its head to protect it from predators.

  3. Megalops Larva: The baby is now taking on more of a crab-type look. 

  4. Juvenile: These little fellows are still so tiny (only about the size of a dime) and vulnerable to the open ocean. They tend to settle on the bottom of the ocean floor and molt several times, while growing, before becoming an adult crab.  

  5. Mature Adult: This Dungeness crab no longer has an attitude toward its mother and can come and go as it pleases. Actually, a mature adult crab is only about 2 years old and does not become an official adult until it goes through about 10 molts. It is now ready to go find a mate and start this cycle all over again! 

Factors that Affect the Dungeness Crab Population

The survival and amount of crab that settle in one particular area varies depending upon a few factors.

  • Predation
  • Food availability
  • Overfishing
  • Water temperature
  • Ocean currents 

The good news is that many people in the government, fish and wildlife organizations, nonprofits, and conservationists are ensuring that the population of Dungeness crabs stay stable and they are caught and harvested in a sustainable manner. 

Those at Fathom Seafood do their part as well to ensure the Dungeness crab they catch are done so ethically and sustainably. 

Don’t let this talk about crab molting and reproduction make you any less hungry for crab! Check out the options at Fathom Seafood and get fresh, live Dungeness crab shipped directly to your door within the next 24 hours. 24 hours you can have a sweet and delectable crab meal on the table for you and your family. They even have a wholesale program if that is what you need.    

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