CAPE CANAVERAL, Fla. — SpaceX launched thousands of tiny sea creatures to the International Space Station on Thursday, along with a plaque-fighting toothpaste experiment and powerful solar panels. The 7,300-pound shipment — which also includes fresh lemons, onions, avocados and cherry tomatoes for the station’s seven astronauts — should arrive Saturday. SpaceX’s Falcon rocket blasted into the hazy afternoon sky from Kennedy Space Center. The first-stage booster was new for a change, landing on an offshore platform several minutes after liftoff so it can be recycled for a NASA astronaut flight this fall. The Dragon cargo capsule — also brand-new — is delivering the first of three sets of high-tech solar panels designed to bolster the space station’s aging power grid. Astronauts will conduct two spacewalks this month to help install the two rollout panels alongside solar wings that have been in continuous operation for 20 years.