Michael Quinton / Alaska Moose (Alces alces gigas) pair of males confronting each other in the fall, Alaska

Michael Quinton / Alaska Moose (Alces alces gigas) young bull charges young Timber Wolf (Canis lupus), Teklanika River, Denali National Park and Preserve, Alaska

Flip Nicklin / Polar Bear (Ursus maritimus) fights with camp dogs, Canada

Flip Nicklin / Polar Bear (Ursus maritimus) near carcass with camp dogs surrounding it, Canada

Mark Moffett / Goat Fly (Phytalmia mouldsi) male flies eye to eye as they guard females using oviposters to deposit fertilized eggs, Queensland, Australia

Mark Moffett / Trap-jaw Ant (Acanthognathus teledectus) worker defends herself and larva from Army Ant, Costa Rica

Mark Moffett / Marauder Ant (Pheidologeton diversus) pair defending the trunk trail from intruding Army Ant (Leptogenys sp) pair, India

Mark Moffett / Trap-jaw Ant (Acanthognathus teledectus) worker defends herself and the larva she defends against an Army Ant by shooting venom at the intruder, Costa Rica

Jabruson / Four Dwarf mongoose {Helogale parvula} surround African puff adder {Bitis arietans} Tsavo East NP, Kenya

Paul D Stewart / Illustration of Laelaps (Dryptosaurus) confronting Elasmosaurus with Hadrosaurus foraging in the background. From Edwin Drinker Cope 'The fossil reptiles of New Jersey' in 'American Naturalist' vol 3...

Solvin Zankl / Common fruit fly (Drosophila melanogaster) laboratory culture Curly (wings turn up) mutant, the mutations are used as genetic markers in gene research, Vienna Drosophila RNAi Center, Institute for Mol...

Solvin Zankl / Common fruit flies (Drosophila melanogaster) laboratory culture of flies showing Yellow (yellow pigmentation), Curly (wings curl away from body) and Orange (less red pigmentation in eyes) mutations. T...

Solvin Zankl / Common fruit flies (Drosophila melanogaster) laboratory culture of flies showing Yellow (yellow pigmentation), Curly (wings curl away from body) and Orange (less red pigmentation in eyes) mutations. T...

Solvin Zankl / Common fruit fly (Drosophila melanogaster) White type mutant (eyes lack pigmentation and appear white) laboratory culture. Vienna Drosophila RNAi Center, Institute for Molecular Pathology, Austria

Solvin Zankl / Common fruit fly (Drosophila melanogaster) showing the Orange mutation (eyes have fewer red pigments than normal) the mutation is used as a genetic marker. Vienna Drosophila RNAi Center, Institute for...

Solvin Zankl / Common fruit fly (Drosophila melanogaster) laboratory culture Curly (wings turn up) and Orange (eyes are less red) mutant, the mutations are used as genetic markers in gene research, Vienna Drosophila...

Solvin Zankl / Mating behaviour in Common fruit flies (Drosophila melanogaster) studied in laboratory for gene research, a Curly (wings turn up) and Orange (less red pigment in the eyes) mutant female rejects the ma...

Solvin Zankl / Common fruit fly (Drosophila melanogaster) laboratory culture Yellow (yellow body pigmentation) and Curly (wings turn up) mutant, the mutations are used as genetic markers in gene research, Vienna Dro...

Solvin Zankl / Common fruit fly (Drosophila melanogaster) showing the Curly mutation (wings curl away from the body) The mutation is used as a genetic marker. Vienna Drosophila RNAi Center, Institute for Molecular P...

Solvin Zankl / Common fruit fly (Drosophila melanogaster) White type mutant (eyes lack pigmentation and appear white) laboratory culture. Vienna Drosophila RNAi Center, Institute for Molecular Pathology, Austria

Solvin Zankl / Common fruit fly (Drosophila melanogaster) laboratory culture of flies demonstrating various mutations at Vienna Drosophila RNAi Center, Institute for Molecular Pathology, Austria, September 2010

Solvin Zankl / Common fruit fly (Drosophila melanogaster) showing Stubble mutation (hairs are shorter and thicker than wild type) and If mutation (irregular facets, a dominant mutation that results in small eyes wit...

Solvin Zankl / Common Fruit Fly (Drosophila melanogaster) showing Antennapedia mutation (legs instead of antennae growing from the head). The mutation is used as a genetic marker, Vienna Drosophila RNAi Center, Inst...

Solvin Zankl / Common fruit fly (Drosophila melanogaster) showing Stubble (hairs shorter and thicker) and Drop (very small eyes) mutations. Mutations used as genetic markers. Vienna Drosophila RNAi Center, Institute...