Piotr Naskrecki / Horseshoe Crab (Limulus polyphemus) blood which is blue due to copper-based hemocyanin and is widely used in the medical field, Delaware

Tim Fitzharris / Northern Elephant Seal (Mirounga angustirostris) two bulls fighting in the surf, California

Michael Durham / Sheep Tick (Ixodes ricinus) female engorged after a blood meal, northeast Oregon

Gerry Ellis / Domestic Cat (Felis catus) with songbird, Portland, Oregon

Flip Nicklin / Humpback Whale (Megaptera novaeangliae) bloody dorsal fin, Hawaii

Jim Brandenburg / Timber Wolf (Canis lupus) track of injured individual, Minnesota

Thomas Mangelsen / Elk (Cervus elaphus) calf killed by Mountain Lion (Puma concolor), National Elk Refuge, Wyoming