Have you ever wanted to pet an otter? Later this year, you’ll get your chance. About 1,200 animals — 300 species — will soon call Littleton’s Southwest Plaza mall home. SeaQuest Interactive Aquarium is expanding its reach to the Denver suburb. It already has locations in Las Vegas, Fort Worth, Texas, and Layton, Utah. “The mall reached out to us,” said Elsa Macdonald, national marketing director for SeaQuest, as part of an effort to boost the shopping center’s industry.