The semi-transparent Thornback ray has a ghostly smile This baby ray born into captivity in the UK is making waves for its ghostly other-world smile. The semi-transparent fish left visitors to a popular aquarium reeling after it gave them an alien-like grimace The young fish is just 12cm long and is one of a dozen hatched from eggs known as "mermaid's purses". They were all born as part of a captive breeding programme at the Blue Reef Aquarium at Southsea, Hants. The baby rays are currently being looked after in a special nursery tank - but once large enough, they will join adult Thornbacks and a variety of sharks in a huge, open-top pool. A Blue Reef spokesman said the babies were proving very popular with visitors. He said: "Their faces are very distinctive, especially the apparent smile.