Blue crabs are a popular species along the Atlantic and Gulf Coasts, where they play important roles in the marine ecosystem and in people’s diets.
Knowing how to tell the difference between male and female blue crabs is important for a few reasons, including understanding their biology and behavior and following local harvesting guidelines.
Here’s a quick guide for how to tell male from female blue crabs by looking at a few key physical characteristics.
Apron Shape
One of the easiest ways to tell the difference between a male and female blue crab is to look at the shape of the abdominal flap, or “apron,” on the underside of the crab.
Male Apron
The male blue crab has a long, slender, triangular apron that is adhered tightly to its body. Some people say the shape resembles the Washington Monument or a capital T.
Female Apron
The female apron is wider and more rounded. While immature females have a triangular apron, mature females have a rounded, dome-shaped apron sometimes described as beehive- or U-shaped.
The wider apron on the mature female provides room for her to carry eggs.
Claw characteristics
The claws of a blue crab are another way to tell whether you’re looking at a male or a female.
Male claws
Male blue crabs tend to have larger and thicker claws than females. The larger of the two claws, known as the crusher claw, is especially noticeable.
Also, the blue coloring on the claws may be a more intense shade of blue in males.
Female claws
In general, female blue crabs have smaller and less robust claws than males.
The tips of the claws often have red or orange coloring, which is sometimes referred to as “painted nails.”
Size difference
Typically, male blue crabs get bigger than females. However, this isn’t the best way to tell the difference.
Environmental factors and age can change the size of a crab. Some females grow to a large size. Small, young males can also be mistaken for females.
Use size as one clue, but don’t depend on it. Look for other characteristics to tell male and female blue crabs apart.
Reproductive Organs
Male and female crabs have different locations for their reproductive organs. In males, they’re on the thorax. In females, they’re located on the abdomen.
However, you may not be able to see these organs without a closer look.
Frequently Asked Questions
Do female blue crabs have red claws?
Not exactly the whole claw, but female blue crabs are easily identified by the bright red tips on their claws, often described as “painted fingernails.” Male blue crabs, on the other hand, have blue claws, hence the name!
Is it better to eat male or female blue crabs?
That’s a matter of personal preference! Some people prefer the taste and texture of male crabs, finding them meatier. Others seek out female crabs, especially when they’re carrying eggs (referred to as “sponge crabs” or “berried females”), as the eggs are considered a delicacy by some. However, it’s important to consider the sustainability implications before consuming sponge crabs (see below).
Should you keep female blue crabs?
This is a complex question with ethical and ecological dimensions. Many areas have regulations regarding harvesting female blue crabs, particularly berried females, to protect the crab population. It’s crucial to check local fishing regulations and guidelines before harvesting any blue crabs, and many conservationists advocate for releasing berried females to help ensure the future of the blue crab population. Sustainability is key!
To Conclude
If you want to tell a male blue crab from a female, pay attention to several characteristics. The shape of the apron is the most reliable indicator, but claw size and color can also give you clues.
Using a combination of methods will give you the most accurate results. Knowing the sex of blue crabs can be useful to recreational crabbers and anyone interested in marine biology.