Staff at a North Carolina aquarium are baffled as a female stingray, Charlotte, is pregnant despite living without a male companion.
The announcement was made by the Aquarium & Shark Lab by Team ECCO in Hendersonville via a Facebook post on Tuesday, February 13.
Extraordinary Stingray Pregnancy Surprises Aquarium Staff
Charlotte, a rust-colored stingray housed in a North Carolina aquarium in the Appalachian Mountains, has defied expectations by becoming pregnant despite residing far from her natural habitat in southern California and without a male companion for over eight years.
The announcement of her unexpected pregnancy was made by Brenda Ramer, the executive director of the Aquarium and Shark Lab. Despite the aquarium's astonishment, Ramer playfully attributed Charlotte's condition to a Valentine's Day surprise, expressing enthusiasm about the impending birth of as many as four pups within the next two weeks.
Speculation arose about the origin of the pregnancy, as Charlotte, sharing a tank with five small sharks, couldn't have mated with them, according to an expert on stingrays. Ramer initially jokingly suggested a possible interspecies hookup but later clarified that such an occurrence was implausible.
The small aquarium is operated by the educational nonprofit Team ECCO, founded by Ramer, with a mission to foster scientific interest among local schoolchildren.
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A Rare Parthenogenesis Case in Stingray Reproduction
The team clarified that Charlotte's situation does not involve cloning; instead, it is a case of parthenogenesis. In this form of asexual reproduction, offspring develop from unfertilized eggs, and there is no genetic contribution from a male. This relatively uncommon phenomenon is observed in specific insects, fish, amphibians, birds, and reptiles, but not in mammals.
Parthenogenesis, observed in over 80 vertebrate species, occurs more frequently in fish or lizards, constituting about half of documented cases. While it's uncommon for complex vertebrates like sharks, snakes, and large lizards to engage in asexual reproduction, instances like Leonie initially puzzled scientists.
Instances of parthenogenesis have been documented in species such as California condors, Komodo dragons, and yellow-bellied water snakes.
The rarity of tracking parthenogenesis in the wild leads to many "firsts" being observed in animals under human care. In mammals, no known cases of parthenogenesis exist due to the reliance on genomic imprinting, a process crucial for their complex reproductive systems.
Genomic imprinting acts like a molecular stamp, designating which genes come from the mother and which from the father, regulating gene activation or deactivation. Without both parents, certain genes would not activate, rendering viable offspring impossible.
Kady Lyons, a research scientist at the Georgia Aquarium, commented on the rarity of Charlotte's pregnancy within the documented cases of round stingrays. While surprised, Lyons mentioned that similar phenomena have been observed in other species of sharks, skates, and rays in captivity.
The pregnancy results from the fusion of a female's egg with another cell, triggering cell division and leading to embryo creation. Despite the uniqueness of such events, Lyons emphasized that it's a natural phenomenon, where the fused cell, known as a polar body, plays a crucial role in the reproductive process.
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Check out more news and information on Parthenogenesis in Science Times.
