Norbert Wu / Electric Catfish (Malapterus sp) at Steinhart Aquarium, San Francisco, California, native to Africa

Claudio Contreras / Prehistoric rock art with depiction of Pronghorn antelope. Boca de San Julio cave, San Francisco Sierra, El Vizcaino Biosphere Reserve, Baja California Peninsula, Mexico.

Claudio Contreras / Prehistoric rock painting at La Pintada cave, Pronghorn antelope, Bighorn sheep and people depicted, San Francisco Sierra, El Vizcaino Biosphere Reserve, Baja California Peninsula, Mexico.

Claudio Contreras / Prehistoric rock painting of Pronghorn antelope and people, at La Pintada cave. San Francisco Sierra, El Vizcaino Biosphere Reserve, Baja California Peninsula, Mexico.

Claudio Contreras / Prehistoric rock painting of Pronghorn antelope and people. La Pintada cave. San Francisco Sierra, El Vizcaino Biosphere Reserve, Baja California Peninsula, Mexico.

Claudio Contreras / Prehistoric rock painting of Pronghorn antelope and Turkey vulture. La Pintada cave. San Francisco Sierra, El Vizcaino Biosphere Reserve, Baja California Peninsula, Mexico, March

Claudio Contreras / Guide in front of prehistoric rock paintings of Bighron sheep and people. La Pintada cave, San Francisco Sierra, El Vizcaino Biosphere Reserve, Baja California Peninsula, Mexico.

Chase Dekker / Bobcat (Lynx rufus) with Botta's Pocket Gopher (Thomomys bottae) prey, Morgan Hill, California

Sebastian Kennerknecht / Snowy Plover (Charadrius nivosus) nest in restored salt pond with shells laid by biologists to increase camouflage possibilities for adults, Eden Landing Ecological Reserve, Union City, Bay Area, Cali...

Sebastian Kennerknecht / Snowy Plover (Charadrius nivosus) biologist, Karine Tokatlian, holding chick during banding, Eden Landing Ecological Reserve, Union City, Bay Area, California

Jaymi Heimbuch / Raccoon (Procyon lotor) juvenile in water, San Francisco, Bay Area, California

Emanuele Biggi / Arboreal salamander (Aneides lugubris) egg on white background, California, USA.