Shark Gives "Virgin Birth" in Detroit
A female white spotted bamboo shark at the Belle Isle Aquarium in Detroit surprised zookeepers in July by giving birth to two babies. Why the surprise? It was a virgin birth: She hadn't been near a male for six years. The mother, who has been housed in a tank with a female brown banded bamboo shark for the last six years, laid a clutch of eggs in April.
That isn't particularly unusual, said Doug Sweet, curator of fishes at the Belle Isle Aquarium. Many animals will lay eggs even without a male to mate with, but the eggs are assumed to be infertile and are discarded. Up until now it's been thought that all shark species use internal fertilization through copulation to produce their young. Once fertilized, many shark species birth their young live; others, like the white spotted bamboo shark, lay eggs. Both the females at Belle Isle had laid eggs in the past, despite their celibacy.
That isn't particularly unusual, said Doug Sweet, curator of fishes at the Belle Isle Aquarium. Many animals will lay eggs even without a male to mate with, but the eggs are assumed to be infertile and are discarded. Up until now it's been thought that all shark species use internal fertilization through copulation to produce their young. Once fertilized, many shark species birth their young live; others, like the white spotted bamboo shark, lay eggs. Both the females at Belle Isle had laid eggs in the past, despite their celibacy.
But instead of throwing them out as usual, Sweet left the eggs in the tank for a while because he had heard of a bonnethead shark at the Henry Doorly Zoo in Omaha, Nebraska, thought to have given a virgin birth last year. He eventually transferred the eggs to a separate tank, and 15 weeks after they'd been laid, the eggs hatched, and the mystery of the virgin birth was repeated.
Rethinking Shark Reproduction
The births have raised questions among scientists as to whether sharks may be able to reproduce parthenogenetically, a mode of reproduction in which the egg is not fertilized. These so-called virgin births are common in invertebrates like snails, but are unusual in higher vertebrates.
"Parthenogenesis has been documented in many reptiles," said Sweet. "There are at least five or six species of snakes, and it's been known in salamanders, lizards, and even a breed of turkeys. But any way you look at it, this is strange." There are possibilities other than parthenogenesis. The Belle Isle white spotted bamboo shark may have been fertilized by a male at a very young age. However, although there have been some random reports of shark species storing sperm for a couple of months or more, six years is a long time, and Sweet thinks in this case it's extremely unlikely.
"We received both of these bamboo sharks from hobbyists, who don't typically keep breeding groups; for one thing their tanks aren't big enough. Usually hobbyists can only buy one egg here and there, and the eggs are typically imported as fertilized eggs. Both the hobbyists who donated these sharks only had one individual. I'm almost dead sure we can rule out long-term sperm storage."
A third possibility is that the Belle Isle bamboo shark is a hermaphrodite, harboring both male and female sex organs, and capable of fertilizing its own eggs.
Hillary Mayell for National Geographic News
September 26, 2002
September 26, 2002
37 comments:
Good day !.
might , probably curious to know how one can make real money .
There is no need to invest much at first. You may commense to receive yields with as small sum of money as 20-100 dollars.
AimTrust is what you thought of all the time
The company incorporates an offshore structure with advanced asset management technologies in production and delivery of pipes for oil and gas.
Its head office is in Panama with structures around the world.
Do you want to become a happy investor?
That`s your chance That`s what you wish in the long run!
I`m happy and lucky, I began to take up real money with the help of this company,
and I invite you to do the same. It`s all about how to select a proper companion who uses your savings in a right way - that`s it!.
I make 2G daily, and my first deposit was 1 grand only!
It`s easy to start , just click this link http://oqusuradel.arcadepages.com/rytaqys.html
and lucky you`re! Let`s take our chance together to get rid of nastiness of the life
Hi !.
You may , probably very interested to know how one can manage to receive high yields .
There is no need to invest much at first. You may start earning with as small sum of money as 20-100 dollars.
AimTrust is what you haven`t ever dreamt of such a chance to become rich
The firm incorporates an offshore structure with advanced asset management technologies in production and delivery of pipes for oil and gas.
Its head office is in Panama with offices around the world.
Do you want to become a happy investor?
That`s your chance That`s what you wish in the long run!
I feel good, I started to take up real money with the help of this company,
and I invite you to do the same. It`s all about how to choose a correct companion who uses your savings in a right way - that`s it!.
I make 2G daily, and my first investment was 500 dollars only!
It`s easy to join , just click this link http://jilasixa.bigheadhosting.net/baqozugu.html
and go! Let`s take this option together to feel the smell of real money
Hello !.
might , probably very interested to know how one can reach 2000 per day of income .
There is no need to invest much at first. You may commense to receive yields with as small sum of money as 20-100 dollars.
AimTrust is what you need
AimTrust represents an offshore structure with advanced asset management technologies in production and delivery of pipes for oil and gas.
Its head office is in Panama with structures everywhere: In USA, Canada, Cyprus.
Do you want to become an affluent person?
That`s your chance That`s what you desire!
I feel good, I began to get real money with the help of this company,
and I invite you to do the same. If it gets down to select a correct partner who uses your funds in a right way - that`s the AimTrust!.
I earn US$2,000 per day, and my first investment was 500 dollars only!
It`s easy to join , just click this link http://humumupa.dreamstation.com/samojoxy.html
and lucky you`re! Let`s take our chance together to become rich
How do i import the songs from my iPhone onto my computer? ok, so i got my iphone 3g a year ago and have been putting songs onto it. now the computer that i have been using has crashed. fixing it, for now, is out of the question. so i have more songs that i want to upload from cds, but on another computer...how do i get the songs that are currently on my iphone AND the songs on the computer so that nothing overrides anything?
________________
[url=http://unlockiphone22.com]unlock iphone[/url]
i have downloaded .ipa files for free off of different websites etc. then i put them in the library then press sync. and this message comes up: the application was not installed on the IPhone because it could not be verified. anyone help please??
________________
[url=http://unlockiphone22.com]unlock iphone[/url]
Good day, sun shines!
There have were times of hardship when I felt unhappy missing knowledge about opportunities of getting high yields on investments. I was a dump and downright pessimistic person.
I have never thought that there weren't any need in big starting capital.
Now, I feel good, I begin to get real money.
It's all about how to select a proper companion who uses your funds in a right way - that is incorporate it in real deals, parts and divides the income with me.
You may get interested, if there are such firms? I'm obliged to answer the truth, YES, there are. Please get to know about one of them:
http://theblogmoney.com
Predilection casinos? flog one revealed this open [url=http://www.realcazinoz.com]casino[/url] official and putting together online casino games like slots, blackjack, roulette, baccarat and more at www.realcazinoz.com .
you can also reading our up to rendezvous [url=http://freecasinogames2010.webs.com]casino[/url] sidestep at http://freecasinogames2010.webs.com and debilitated dean suitably dippy !
another one of a kind [url=http://www.ttittancasino.com]casino spiele[/url] fetter of events is www.ttittancasino.com , in the thoroughfare of german gamblers, span unrestrained online casino bonus.
Hello. My wife and I bought our house about 6 months ago. It was a foreclosure and we were able to get a great deal on it. We also took advantage of the 8K tax credit so that definitely helped. We did an extensive remodeling job and now I want to refinance to cut the term to a 20 or 15 year loan. Does anyone know any good sites for mortgage information? Thanks!
Mike
limit extinguished this unrestricted [url=http://www.casinoapart.com]casino[/url] hand-out at the outwit [url=http://www.casinoapart.com]online casino[/url] criterion with 10's of redone [url=http://www.casinoapart.com]online casinos[/url]. interest of the mountains [url=http://www.casinoapart.com/articles/play-roulette.html]roulette[/url], [url=http://www.casinoapart.com/articles/play-slots.html]slots[/url] and [url=http://www.casinoapart.com/articles/play-baccarat.html]baccarat[/url] at this [url=http://www.casinoapart.com/articles/no-deposit-casinos.html]no appropriate singular's run away from of casino[/url] , www.casinoapart.com
the finest [url=http://de.casinoapart.com]casino[/url] to UK, german and all during the world. so on the side of the crest [url=http://es.casinoapart.com]casino en linea[/url] unman us now.
Glad to materialize here. Good day or night everybody!
Sure, you’ve heard about me, because my fame is running in front of me,
my parents call me Peter.
Generally I’m a venturesome gambler. all my life I’m carried away by online-casino and poker.
Not long time ago I started my own blog, where I describe my virtual adventures.
Probably, it will be interesting for you to find out my particular opinion on famous gambling projects.
Please visit my web site. http://allbestcasino.com I’ll be interested on your opinion..
Hello. And Bye.
buy ambien can cut 10mg ambien half - took 3 ambien cr
can you buy xanax online legally xanax vs sleeping pills - xanax overdose much too much
buy diazepam diazepam side effects heart - diazepam online cheap
zolpidem overdose zolpidem tartrate 20 mg - ambien side effects blood pressure
xanax without prescription xanax withdrawal dreams - xanax withdrawal irritability
buy valium where to buy valium online without script - valium dosage women
order lorazepam ativan dosage paramedic - picture generic lorazepam 1mg
pharmacokinetics of diazepam long does 2mg diazepam stay system - diazepam show on drug test
xanax drug xanax round white - xanax 2mg alcohol
ativan cost ativan withdrawal symptoms - ativan ep 905
buy diazepam online order diazepam online canada - diazepam vs soma
buy xanax online buy xanax in australia - xanax dosage with alcohol
order ativan ativan side effects neonates - what is ativan generic name
buy xanax online no prescription all kinds xanax pills - buy good xanax online
ativan online ativan dosage for the elderly - ativan sublingual overdose
can you buy xanax online legally buy xanax in tijuana - what color is xanax 1mg
soma carisoprodol carisoprodol used treat - buy somatropin mexico
ordering ambien online effectiveness generic ambien cr - ambien cr controlled substance
soma without prescription somanabolic muscle maximizer is fake - safe place buy soma online
purchase soma buy soma online no prescription overnight - buy soma online from canada
order soma online carisoprodol 350 mg dan - soma drug experiences
ambien drug ambien generic pill shape - buy ambien online no prescription
purchase ambien ambien cr tab 12.5mg - ambien uds
zolpidem 10 mg ambien dosage 15mg - ambien and alcohol interaction
soma online soma drug ingredients - generic equivalent soma
The information were very helpful for me, I've bookmarked this post, Please share more information about this
Thanks
Post a Comment