Double-Sex Crab Caught in Chesapeake Bay.

iGary

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Part Male, Part Female, Fully Mysterious
Dual-Sex Crab Found in Bay Could Yield Clues to Species' Genetics and Mating Habits

By David A. Fahrenthold
Washington Post Staff Writer
Thursday, June 16, 2005; Page B01


Watermen say that female blue crabs "paint their fingernails," meaning the tips of their claws turn bright red as they age. The male crabs, on the other hand, have sky-blue claws -- a sign as masculine as a mustache in the world of crustaceans.

So when Robbie Watson dumped out a crab trap and found a specimen with one red claw and one blue one, the discovery stopped him.

As his boat, the Wharf Rat, moved on to other crab pots, Watson, 42, studied the crab. Underneath, its shell should have had a design looking roughly like the U.S. Capitol dome if it were female, or a Washington Monument pattern if it were male.

Instead, Watson found a wavy arrow, which seemed to be a combination of both sexes.

"It was unreal," Watson said. "I've never seen anything like that, and I've worked the water all my life.''

Scientists said the crab, caught May 21 near Gwynns Island in the lower bay, is an extremely rare creature called a "bilateral gynandromorph" -- that is, split between two genders -- with its right side female and its left side male.

The last time such a crab was caught in the Chesapeake region was about 1980, scientists said. Since then, watermen have hauled in millions of crabs annually without noticing another.

On the day they caught it, Watson and boat captain David Johnson had been crabbing since about 5:30 a.m., dumping females into one basket and males -- who are often bigger and sell for twice as much -- in another.

"What basket should we put it in?" Watson asked the captain.

"I think we're going to put it in one up front," Johnson, 50, recalled telling him.
 

iGary

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Precisely.

They have it at a marine museum (not sure which one) right now and "he/she/it" is doing very well.
 

yellow

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Oct 21, 2003
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The last time such a crab was caught in the Chesapeake region was about 1980, scientists said. Since then, watermen have hauled in millions of crabs annually without noticing another.
Do they normally feel each and every one up? :)

Cool story though.. I wonder if it's fertile or not. If so, would it's offspring be bilateral gynandromorph as well? Could we be defeating darwinism here?
 

iGary

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stridey said:
Well, as the article said, they seperate the males and females to sell seperately. So, yes.
Females are usually sold to picking houses for canned or packed crabmeat; males usually are sold to reataurants and seafood outlets.

The males are much tastier and larger than the females.

Males are called "Jimmies" and sorted in sizes "1,2 or 3." females are normally sold as females and called "sooks."

More Chesapeake Bay trivia than you asked for. :D
 

jared_kipe

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Don't matter, tastes the same with a little butter.

Seriously though, I wonder what would cause such an odd mutation. One half of the body has different DNA then the other side? How does that happen?
 

GFLPraxis

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Ever notice some job applications have, Male, Female, and Other as options?

I guess we finally know what the "Other" is for ;)
 

quagmire

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jared_kipe said:
Don't matter, tastes the same with a little butter.

Seriously though, I wonder what would cause such an odd mutation. One half of the body has different DNA then the other side? How does that happen?
It is like our species. Birth defects. You know some humans are born with female and male parts too you know. What causes that mutation?
 

wdlove

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Seeing the picture of the he/she crab above is certainly a thing of beauty to behold. I was actually skeptical of the coloring till I saw the picture. Hopefully the crab will have a long and healthy life.
 

Mr. Anderson

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Truly odd - I'm not a big fan of crabs, I've had my share, though. I'm just not into the mallet whacking, shell cracking mess. I'd prefer crab cakes :D

But considering that there hasn't been one seen in 25 years says a lot - but I'm wondering if it can reproduce? There was no mention of that in the story.

D
 

emw

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Mr. Anderson said:
Truly odd - I'm not a big fan of crabs, I've had my share, though.
Not something I'd think you'd want to brag about...

:eek: ;)
 

Dros

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Jun 25, 2003
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This sort of thing happens when one of the sex chromosomes gets lost in the first division of the egg into two cells. If the original fertilized embryo was meant to be a female and had 2 X chromosomes (crabs may have an odd system for sex chromosomes, but the theory would be the same), and one cell ended up with 2 Xs and the other cell lost 1 and had only 1 X, then all the cells on one side would continue to have 2 and the other side just 1. There have been lobsters found like this as well.

Chromosomes do get lost infrequently. You may have some cells in your body like this. If it happens late, then only a few cells will be like this and you would never notice. And since there are trillions of cells in your body, having it happen in the first division is rare.
 

jared_kipe

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quagmire said:
It is like our species. Birth defects. You know some humans are born with female and male parts too you know. What causes that mutation?
Not true, this is almost nothing to do with that, its symmetric, show me a picture where 1/2 of a human is male, and the other 1/2 is female.

Having both parts is nothing like being 1/2 male and 1/2 female.
 

pooky

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Jun 2, 2003
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Dros said:
This sort of thing happens when one of the sex chromosomes gets lost in the first division of the egg into two cells. If the original fertilized embryo was meant to be a female and had 2 X chromosomes (crabs may have an odd system for sex chromosomes, but the theory would be the same), and one cell ended up with 2 Xs and the other cell lost 1 and had only 1 X, then all the cells on one side would continue to have 2 and the other side just 1. There have been lobsters found like this as well
Actually, many crustaceans have environmental sex determination, not chromosomal like mammals and birds. For these animals, chromosomes have nothing to do with their sex, instead the environment during a critical phase of development is instead important. Examples of this are crocodilians, where if the eggs are at one temperature, they'll all be male, but raise the temp by a few degrees, and they'll be female. Some species (i.e. clownfish - like Nemo from Finding Nemo) change sex during their life as their social position changes - they are male at birth, and as they get larger and more dominant, they eventually switch to female.

For this crab, perhaps one side of the body was exposed to a condition or trigger or chemical that caused it to have a different sex than the other half. A mutation that screws up the mechanism of sex determination could also do it.
 

jared_kipe

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pooky said:
Actually, many crustaceans have environmental sex determination, not chromosomal like mammals and birds. For these animals, chromosomes have nothing to do with their sex, instead the environment during a critical phase of development is instead important. Examples of this are crocodilians, where if the eggs are at one temperature, they'll all be male, but raise the temp by a few degrees, and they'll be female. Some species (i.e. clownfish - like Nemo from Finding Nemo) change sex during their life as their social position changes - they are male at birth, and as they get larger and more dominant, they eventually switch to female.

For this crab, perhaps one side of the body was exposed to a condition or trigger or chemical that caused it to have a different sex than the other half. A mutation that screws up the mechanism of sex determination could also do it.
Never the less, the symmetry is odd, and all the things you talked about would be very hard to expose only 1/2 of something to.