Aquarium staff in Louisiana have been left baffled by a miraculous ‘virgin birth’ in their shark exhibit.
‘Yoko’ the young swell shark (Cephaloscyllium ventriosum) was born in an all-female tank at Shreveport Aquarium.
Amazingly, the two female sharks in the tank – one of which is Yoko’s mum – had not been in contact with a male in more than three years, staff said.
And with the gestation period of swell sharks at somewhere between nine and 12 months, this means conception must have occurred some other way.
‘This situation is incredible and shows the resilience of this species,’ said Greg Barrick, curator of live animals at Shreveport Aquarium.
‘It really proves that life finds a way.’
‘Yoko’ is thought to be the result of parthenogenesis – a rare type of asexual reproduction where offspring develop from unfertilised eggs.
The process is extremely rare in nature, although it is found in some other species, most notably mayflies, turkeys, pythons and boa constrictors.
Aquarium staff are baffled by a miraculous ‘virgin birth’ in their shark exhibit. ‘Yoko’ the young swell shark was born to a mum in an all-female tank at Shreveport Aquarium, Louisiana
It is not entirely clear what triggers certain species to undergo this process, or what connects the species that have this capability.
The egg was first identified by aquarium staff about eight months ago, although it may have remained undetected for one to two months prior to this.
It hatched on January 3 and Yoko is now ‘thriving’, Shreveport Aquarium said in a statement on its website.
Instead of parthenogenesis, there’s also the possibility Yoko’s mum experienced delayed fertilization, where fertilization occurs long after mating.
In the wild, some animals postpone the development of their embryos to await better conditions for having offspring.
But it’s unclear why delayed fertilization would have occurred for Yoko’s mum in captivity.
To learn more, staff will soon perform genetic testing on Yoko once it is big enough for a blood test, likely after a few months.
‘We are very excited in the coming months to confirm whether this was indeed a case of parthenogenesis or if it was delayed fertilization,’ added Barrick.
Baby Yoko (pictured) is ‘currently thriving’, Shreveport Aquarium said in a statement on its website
Shreveport Aquarium said: ‘The new swell shark, affectionately nicknamed Yoko after the Chumash word for shark ‘onyoko, is thriving under the care of our dedicated aquarists’
The new swell shark is called Yoko, not after the famous Japanese conceptual artist but after the Native American Chumash word for shark – ‘onyoko’.
Unfortunately, young sharks born through such rare reproductive events often face ‘significant challenges’ and die younger.
According to the aquarium, Yoko’s time could ‘be brief’ but if so she will ‘still leave an unforgettable legacy’.
‘[She is] contributing invaluable insights to the study of shark reproduction and conservation efforts,’ it said.
Virgin births like this are rare in nature and in captivity, but similar cases do exist.
Last year, a boa constrictor at a school in Portsmouth gave birth to 14 babies despite not having the opportunity to mate.
Prior to this, a stingray called Charlotte in North Carolina was said to be pregnant due to parthenogenesis, having not shared a tank with a male.
Charlotte the stingray died last summer due to a rare reproductive disease – although doubts over her pregnancy were later revealed.
Certain animals are capable of reproducing through ‘parthenogenesis’ in which the egg is fertilised with cells from the mother rather than by a male
When threatened, the swell (Cephaloscyllium ventriosum) shark swallows seawater, which causes its belly to swell and deters predators (file photo)
The swell shark (Cephaloscyllium ventriosum) is a shark species native to the coastal waters of the eastern Pacific.
Their range stretches from Monterey Bay in California to southern Mexico and also along the coast of Chilie.
It is known for its unique ability to swell their bodies to twice the normal size using seawater in order to deter predators.
People don’t catch swell sharks for food, but the sharks are caught accidentally as bycatch in commercial lobster and crab traps, gillnets and trawl nets.
‘Because sharks take five to 20 years to mature and have few young, accidental catches like these threaten shark populations around the world,’ says Monterey Bay Aquarium.
WHAT IS A SWELL SHARK AND HOW DO THEY REPRODUCE?
This shark gets its name from an unusual behaviour it displays when threatened by a predator.
When threatened, the swell shark swallows vast amounts of seawater, which causes its belly to swell and makes it difficult for predators to eat
The swell shark species is oviparous which means that its eggs protect and nourish an embryo until it grows to term and hatches.
Fertilization is internal, but little is known about the mating ritual of swell sharks.
After mating, two greenish amber eggs are deposited and become attached, often with the aid of the mother, to substrate items such as rocks and algae, via wiry tendrils of egg case material at the corners of the egg case.
A large yolk, attached to the embryo by way of a yolk stalk, provides nutrition to the embryo during the gestation period, which averages 9-12 months and is, in degree, dependent on water temperature.
