See that pale thing poking out from the underside of this shark? Nope, it’s not a fin, but it is in fact the head of a pup emerging from its mother. While an image of an animal giving birth may not seem particularly breathtaking, shark reproduction is relatively poorly understood, and this could well be the first time that an oceanic shark has ever been photographed during the event.
The picture was taken on April 4, 2013, during a research dive in the Philippines. Scientists from the University of Chester and the Thresher Shark Research and Conservation Project have been monitoring this particular area, a shallow undersea mountain, because pelagic thresher sharks have been regularly spotted interacting with cleaner fish here for the past two decades. These clients visit this “cleaning station” in order to have loose skin and parasites gnawed off by two different species of wrasse, L. dimidiatus and T. lunare, which is a mutually beneficial interaction.
During the wee hours of the morning, a large female shark was observed swimming back and forth across the area, apparently distressed by something. The team could see that a cleaner wrasse was nibbling away at its pelvic region, but they were too far away to work out what could be causing her to be agitated. The researchers observed the shark for around four minutes, during which they took a photograph for later identification and analysis.
When lead scientist Dr. Simon Oliver first laid his eyes on the processed image, which soon revealed the true nature of the shark’s agitation, he “freaked out.” Not only was this the first time that cleaners have been observed interacting with a marine organism while it gives birth, but it is the first documented case of any oceanic shark species giving birth. The image, which has now been published in Coral Reefs, has been described as “amazing” by experts. Not everyone agrees that it is important for shark conservation, however, although Oliver argues that it highlights the need to protect this spot.
“It looks like this area is not just a cleaning station, which is already massively essential, it’s also serving as a pupping ground,” Oliver explains to BBC News. “We’ve seen lots of [pregnant] females there, so I don’t think this is a one-off.” That’s why Oliver and his colleagues are now working towards getting the seamount classified as a marine protected area. Thresher sharks are listed as vulnerable by the IUCN red list because of their declining populations. Their numbers are dwindling because they are targeted by humans for meat and sharkfin soup, and their liver oil is also processed for vitamins.
[Via BBC News and Coral Reefs]
