Merlin Entertainments has approached SeaWorld Entertainment about a possible investment, as first reported yesterday by Bloomberg. SeaWorld shares spiked in the aftermarket on the news, increasing its market cap at one point to nearly $1.5 billion.

Why it matters: Sea World's reaction to this approach may give some insights into its level of desperation, four years after the critical Black Fish documentary. Reports are that it wants to sell the entire company, but Merlin likely is only seeking the Busch Garden parks given its internal policy against keeping marine mammals in captivity. If it proceeds with Merlin, that means Sea World isn't expecting suitors for the whole package.

Key number is 23. That's the per share price that China's Zhonghong Zhuoye Group paid earlier this year to buy a 21% stake in Sea World from The Blackstone Group. Yesterday, Sea World shares closed at just $14.11.

Bloomberg goes deeper: "The offer comes as SeaWorld... struggles to stem declines in sales and the stock price of the Orlando-based park owner once famous for its killer whales. For Merlin, a deal by the operator of the London Eye and Madame Tussauds waxworks would mark a continuation of its strategy to expand internationally to cope with a drop in day-trippers to the British capital following terrorist attacks in London and Manchester."