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Ray Eggs Join Aquarium

April 22, 2013

Ray Egg Case Undulate Ray PIC Jacques SixHastings Blue Reef Aquarium is hoping to hear the splash of tiny fins in the coming months with the arrival of no fewer than 11 ray egg-cases.

The eggs, which were laid at their sister-aquarium in Bristol as part of a captive breeding programme, belong to the undulate ray which is now considered to be endangered in the wild.

If all goes according to plan, the eggs should start to hatch out over the summer.

Blue Reef’s Curator Chris Ireland said: “Many species of European sharks and rays are increasingly coming under threat of extinction in the wild.

“It would be great if we were able to successfully breed this particular species in captivity,” he added.

Found throughout European waters, the undulate ray can grow up to 100cm in length, live for around 20 years and is known for the striking patterns on its back.

It was officially declared ‘Endangered’ in the IUCN Red List of Threatened Species in 2008 which means it faces a very high risk of extinction in the near future.

In 2007 the fish was included in the UK Biodiversity Action Plan and in 2009 it received full protection from the European Council meaning that it cannot be retained or landed if accidentally caught by fishermen.

The undulate ray is oviparous, which means that it lays eggs, and it has been known to produce huge numbers of them. One specimen was recorded as having laid no fewer than 88 eggs over a 77-day period.

The eggs, which are often washed up empty on beaches and known as mermaids’ purses, take around seven months to hatch.

The undulate ray is one of the most distinctive rays to be found in UK water. This species is patterned with long, wavy, dark lines edged with white spots that run parallel to the wing margins.

Rays belong to the same family as sharks and are effectively ‘flattened-out’ versions of their close cousins.  UK waters are home to at least 15 different species including the electric ray and the common skate, which can reach lengths of up to three metres.

Recent research has revealed that embryonic sharks and rays developing inside their egg-cases can sense external electric currents and remain motionless when a would-be predator approaches.