The purpose the Crossroads operation was to investigate the effect of nuclear weapons on a fleet of 95 target ships. Assembled in Bikini Lagoon, the fleet was hit with the two (ABLE and BAKER) detonations of plutonium implosion-type nuclear weapons. Both test incorporated animals to test the effects of exposure to the bomb and the resulting radiation.  The ABLE test included a greater number and variety of animals for testing. Hundreds of animals including goats, pigs, guinea pigs, mice and rats, had been placed on 22 target ships in stations normally occupied by soldiers, and were held in place by small frames and cages. Because ABLE was off its mark, producing a smaller explosion, and the spread out nature of the ships, the immediate blast killed about 10% of the animals.  However, many more animals died days later from radiation, and a number of surviving animals were later killed as part of scientific testing.  One little pig, named #311, managed to make it off of the Japanese test ship, named the Sakawa, and was later found swimming in the lagoon.  The pig was later given to the Smithsonian’s National Zoological Park, were it became a popular heroine of atomic survival, despite becoming completely sterile.

http://www.coldwarla.com/sfva-goat-memorial.html

https://www.pond5.com/fr/stock-footage/item/77893605-2016-operation-crossroads-atomic-bomb-testing-animal-experim