Blue Crab Reproduction Adapted from a presentation by Dr. Dan Rittschof Rachel Carson Reserve (NC) And the State of Maryland Department of Natural Resources

http://www.dnr.state.md.us/baygame/bluecrab.asp

Zoea Newly hatched larvae are called zoea. They are microscopic planktar until the 6th or 7th molt.

Megalops The post-larval form is the megalopa. It’s starting to look like a crab and is starting to live life as a benthic critter.

After metamorphosis, the megalopa becomes a “first crab”. These tiny (less than 1 cm) crabs will continue to molt until they reach maturity at 12 to 18 months.

Males AKA: Jimmys Have blue claws and an abdomen resembling the Washington Monument.

Females AKA: Virgins (before the 23rd molt) and Peelers (after the 23rd molt) Have red claws (“painted fingernails”) and an abdomen that resembles the dome on Capitol Hill.

Mating The female molts 23 times in her life. Just before the 23rd she looks for a male. She smells / tastes the water for male pheromones. When she finds a male… She stops and opens her claws. Urinates to indicate fertility.

Pheromones Steroid-like chemical. Used for communication. Found in crab sperm (M) and urine (F). Water that contains female pheromones can be used to catch males.

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The female stays with the male for about 3 days before she molts. After she molts, they mate and the male protects her until her new exoskeleton hardens. Over the course of her lifetime she will release 50,000 to 60,000 eggs in about 14 clutches.

Egg Bearing Females with eggs are known as sponge crabs. They eggs are yellow at first and darken as they mature. Why the color change? When first laid, the eggs contain yolk. As they develop, the yolk is used up and the space inside the egg is occupied by the crab larvae.

Dud? or Stud?

Males produce about 3 grams of sperm about every 10 days. If forced to mate two times in a row, they can’t mate for 20 days and they become a reproductive “dud”. Some males naturally produce more sperm than others and can reproduce more often. They are considered “studs”.

The End