![]() Forster in 1781 should be used as the senior synonym for the species. The only significant difference we could find from our elaborate analysis is of the external skin color,” said Dahl via e-mail.įinally, the researchers reviewed the nomenclature of the species and suggested that the original name Stegostoma tigrinum proposed by J.R. “The most surprising find of the analysis is of how similar these two morphs are. When examining a mature male of the zebra morph, they found a small, triangular spike extruding from the dorsal terminal of the clasper glands. These animals have two claspers because they are deeply grooved cartilaginous extensions of their pelvic fins. Similar to a penis, claspers are an external appendage found on male Chondrichthyans (sharks, skates, rays, and chimaeras) that deliver sperm inside of a female. The team also described the reproductive organ of mature males who sported this new color morph and were astonished to find a previously unknown spike on the clasper gland. Peter Rask Møller holding up an adult sandy zebra shark at the Danish National Aquarium Den Blå. ![]() Such a separation can be caused by a physical barrier between the groups of individuals, by long geographical distances, or by differences in behaviour preventing the animals from interbreeding despite being in the same area.” They concluded that there are two morphs of the species, the zebra striped morph we all know (the stripes as a juvenile and the spots that replace the stripes as they age) and the new sandy colored morph. “For instance, if we consistently saw a longer caudal fin, or a higher number of vertebrae, or different dermal denticle morphology in one of the morphs it could indicate a genetic separation between them. “We counted the number of vertebrae, the rows of teeth, the number of valves within the intestines, and examined the microscopic details of the dermal denticles (skin teeth), for any such differences,” commented Dahl. Once they realized it was a single species, the team underwent a full morphological study of zebra sharks encompassing morphometric and meristic measurements. Explained Dahl: “Both of these genes have been successful for distinguishing closely related species and could be an indicator of speciation.” Turns out this morph was not a new species and the zebra shark remains a single species based on genetic data from the COI and ND4 markers. Today’s ‘Quordle’ Answers And Clues For Thursday, June 22ĭoes this new beige color morph mean there is a new species of shark? This possibility was evaluated by DNA barcoding using the COI (cytochrome c oxidase subunit 1) and ND4 (mitochondrial NADH dehydrogenase subunit 4) markers. Thus, it is a possibility that the specimen described by Nakaya was the very first encountered sandy morph, which may be different from the color morph here described from off the coast of East Africa. Uniformly colored zebra sharks aren’t exactly new (they’ve been observed off the coast of Australia recently, for example) and in 1973 scientist Kazuhiro Nakaya described a uniformly colored specimen that he referred to as albino even thought the color of the iris was inconsistent with the lack of pigmentation in true albinos (this shark had a dark brown color instead of the tell-tale pink true albinos have). ![]() Zebra sharks are well-known species due to a wide distribution across the Indian and Western Pacific oceans and being quite easy to identify from your average grey-looking shark. Known as carpet sharks due to these animals having a marbled or mottled appearance similar to that of fancy carpet designs, they vary with how they look, the habitat they choose, and their size. Zebra sharks are one of the most iconic of the carpet shark (Orectolobiformes) species, a diverse group originating in the early Jurassic period approximately 200 million years ago that is known for their drastic color changes from juvenile to adulthood. Sandy zebra shark in a bucket at the Danish National Aquarium Den Blå Planet. ![]()
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