It was primate vs. primate at a Brooklyn grocery store when a 10-pound monkey bit a 2-year-old boy being wheeled by his grandparents in a shopping cart, authorities said yesterday.

Darla, a 5-year-old Macaque service monkey who retrieves items for his paraplegic owner, bit Thomas Romano on the arm Sunday after the toddler grabbed her fur three times, the monkey's owner said.

Steven Seidler, 45, of Mill Basin, said he uses a laser pointer to indicate what he needs the monkey to retrieve. At Key Food, Seidler said, Darla was getting items for him off the shelves.

"Darla is my life," Seidler said yesterday. "The kid just reached over and grabbed her. I was shocked she took so much abuse before biting him."

The boy's grandmother, Helene Romano, 47, said the monkey went ape on young Thomas, who did not even notice the animal until he was bitten in the vegetable aisle.

"I'm walking into the Key Food, and the next thing I know, my grandson is like, 'Grandma, Grandma it hurts!' And I'm looking around and I see blood coming out of his arm," Helene Romano said.

Police arrived at the scene after the 4 p.m. incident and did not issue any summonses to Seidler, who had all the proper paperwork for Darla.

"I'm telling the lady, 'Get your kid away from my monkey!'" Seidler recalled.