Tiger keeper Teague Stubbington said: "Jae Jae loves chilling out in the Tiger Territory pool - especially on hot days - but we really wanted him to make better use of it and encourage his natural swimming abilities.
"Not only is swimming fantastic exercise for Jae Jae, the anticipation of getting to the meat stimulates his natural predatory instincts - and catching his 'prey' is the best reward he can get!"
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A lamp in the tower which houses Big Ben is to be switched off for the first time in more than 70 years.
Sir Bruce entertained audiences for more than seven decades.
Work in the tower will also pause over the bank holiday weekend.