In subsequent years, as we learned how to care for the parthenogens better, we had a better rate of survival and some are now fully grown and at almost reproductive age themselves. Of the three eggs that developed embryos in 2006, one hatched and survived for a period of 80 days. We expected a higher level of mortality for the parthenogens as they are less genetically diverse than normal, sexually reproduced offspring. The resulting offspring are therefore not clones as they are not genetic copies of the mother but, they are known as parthenogens. The amazing thing about this process is that the resulting offspring are all genetically unique, unique from the mother and genetically unique from their siblings. Parthenogenesis can take place in the absence of male genetic input and embryos develop from an unfertilised egg. Extremely excited by this discover, we teamed up with a local geneticist to try and prove that what we had discovered was in fact, the first example of parthenogenesis for the species.Īt the time, parthenogenesis had only been seen in captive animals, but now it has also been seen in wild populations, including the elusive sawfish. After a few months, the eggs were examined, and to our surprise, three of the eggs had developed embryos. In 2007, Zebedee started laying eggs again, and we kept the eggs safe in one of our quarantine units. After reading that article, the decision was made to keep the next batch of eggs. I then read an article about a female bonnethead shark in the USA that had reproduced a viable pup on her own, with no genetic contribution by a male, a process known as parthenogenesis. In 2006 Zebedee started to lay eggs in the aquarium but, as there was no male, the eggs were considered unviable and discarded. She was already trained to take food from a stick feeding her was my favourite part of the day. Being a marine biologist, I had dived all around the world for work, but, I had never been lucky enough to encounter a leopard shark in the wild. On my first day of work at the aquarium, I was introduced to my very first ever leopard shark, affectionately known as ‘Zebedee’. My fascination with the leopard sharks, started in 2006 when I took on the position of Assistant Curator at the Burj Al Arab Aquarium in Dubai, UAE. Sadly, their choice of coastal habitat and lack of fear make them vulnerable to fisheries and because of this, wild encounters are becoming rarer. I refer to them as the Labradors of the shark world, and they certainly are a joy to encounter in the wild. Although, I guess if you are a crab, your perspective on this may be very different. They don’t seem to have an aggressive bone in their body, and if they do, I certainly have never seen it. They are a very docile shark and, as they are built like a small armoured tank, they possess little fear of anything, even humans. Their skin is thick and armoured with teeth-like formations called denticles. They possess a rasping jaw plate evolved for crushing their crunchy crustacean prey. It is the only member of the family Stegostomatidae and, its closest shark relative is the colossal whale shark, another favourite of mine.Īs adults, leopard sharks grow to approximately 2.5m in length. They are currently classified as ‘Endangered’ on the International Union for Conservation of Nature’s (IUCN) Red List of Threatened Species, mainly due to overfishing of the species. Leopard sharks are found throughout the Indo-Pacific region. The debate about both common and scientific names is constant and always evolving but, for this story, I will stick with the common name I have always known them as, ‘leopard shark’. Even official scientific names change, the leopard shark was known, until last year, as Stegostoma fasciatum, but then, due to reasons we won’t go into here, the scientific name was changed to Stegostoma tigrinum, just to confuse things a little more. This is undoubtedly the name used most frequently outside of the USA (where confusingly another species of shark also known as a leopard shark resides), and common names for fish and sharks vary enormously, not only internationally, but regionally and sometimes even locally. However, as they progress towards adulthood, the lines morph into spots, and their colouration lightens leading to another commonly used name, the leopard shark. As juveniles they are black with white stripes running along their body, leading to their official common name ‘zebra’ shark. If you’ve never encountered a leopard shark, they are, in my opinion, one of the prettiest.Īs a scientist, I have been pulled up before for using the word ‘pretty’ but, I do think that in the case of the leopard shark, it is an appropriate use of the word.
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