The staff of a Polish zoo were "super happy" to discover four baby rays during a routine morning aquarium check, three of the newborns doing their best to hide, as the flat, disc-like fish very rarely give birth in captivity.
The zoo staff were happy enough to see one baby ray - and then they discovered three more camouflaged against the rocks.
"It was a big surprise," Jakub Kordas, aquarium manager at Wroclaw Zoo in southern Poland, said. "We were super happy to have this one ray.
"As it turned out, a closer inspection allowed the diver to find three more that were perfectly camouflaged, hidden under rock overhangs, in places where they felt safe."
The male and three females measure around 30-34 cm in diameter and have the potential to grow up to 1.8 metres.
Kordas said zoo staff were eager to document their early life as reports about ray breeding in captivity are scarce. Their natural habitats are sandbanks and coral reefs.
They are born rolled up like crepes, and they unfurl after birth, Kordas explained.
"They are picky, they like to fish, they don't particularly like what the literature suggests (they would). They avoid mussel meat and they are not particularly interested in squid and other such invertebrates," Kordas said.
"First experience indicates that herring and mackerel are what they like most."
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