CAPE CANAVERAL, Fla.—A SpaceX shipment of ants, avocados, and a human-sized robotic arm rocketed toward the International Space Station on Sunday. The delivery—due to arrive Monday—is the company’s 23rd for NASA in just under a decade. A recycled Falcon rocket blasted into the predawn sky from NASA’s Kennedy Space Center. After hoisting the Dragon capsule, the first-stage booster landed upright on SpaceX’s newest ocean platform, named “A Shortfall of Gravitas.” SpaceX founder Elon Musk continued his tradition of naming the booster-recovery vessels in tribute to the late science fiction writer Iain Banks and his Culture series. The Dragon is carrying more than 4,800 pounds of supplies and experiments, and fresh food including avocados, lemons, and even ice cream for the space station’s seven astronauts. The Girl Scouts are sending up ants, brine shrimp, and plants as test subjects, while University of Wisconsin-Madison scientists are flying up seeds from mouse-ear cress, …