Terry Whittaker / 2020VISION / Water Vole (Arvicola amphibius / terrestris) foraging by water. Kent, UK, August. Did you know? Although mostly vegetarians, some water voles have been known to eat frogs' legs to get extra protein.

Tim Laman / Large school of Trevally (Caranx) shelter beneath the jetty at Arborek Village. Many village docks in this area act as shelter for these fish, which provide a handy source of protein for villagers in...

David Perpinan / Loggerhead sea turtle (Caretta caretta) juvenile with severe malformation due to inadequate feeding (excessive protein). Small repro only.

Ashley Cooper / Fish caught in Lake Malawi, on drying racks at Cape Maclear, Malawi, Africa.

Ashley Cooper / Fish caught in Lake Malawi, on drying racks at Cape Maclear, Malawi, Africa.

Ashley Cooper / Dried fish at an African market on the roadside in Ckiwawa, Malawi, Africa.

Ashley Cooper / Seal meat butchered by an Inuit man, Ilulissat, Greenland, July 2008.

Ashley Cooper / Seal meat in a bag on the quayside, Ilulissat, Greenland. The seal was shot by an Inuit hunter. July 2008.

Nature Picture Library / Canned whale meat for sale at a souvenir shop for tourists in Japan. The label states that the contents are from an unspecified baleen whale. The sales sign states that whale meat is a food that is go...

Floris van Breugel / High speed exposure of a Fruit fly (Drosophila melanogaster) taken through a microscope. In this image flight muscles express a genetically engineered protein called GCaMP, which fluoresces green in t...

Pete Oxford / Palm weevil grubs (Rhynchophorus palmarum) harvested from Yasuni Biosphere Reserve, for sale as a local food delicacy, Pompeya Market. Amazon Rainforest, Ecuador, South America

Pete Oxford / Palm weevil grubs (Rhynchophorus palmarum) harvested from Yasuni Biosphere Reserve, for sale as a local food delicacy, Pompeya Market. Amazon Rainforest, Ecuador, South America

Pete Oxford / Palm weevil grubs (Rhynchophorus palmarum) harvested from Yasuni Biosphere Reserve, for sale as a local food delicacy, Pompeya Market. Amazon Rainforest, Ecuador, South America

Pete Oxford / Palm weevil grubs (Rhynchophorus palmarum) harvested from Yasuni Biosphere Reserve, for sale as a local delicacy, Pompeya Market. Amazon Rainforest, Ecuador, South America

Floris van Breugel / Green fluorescent proteins, naturally produced by sea anemones, emit green visible light under ultraviolet light seen here in their natural habitat under the stars on the coast of Olympic National Par...

Eric Baccega / Two Grizzly bear cubs (Ursus arctos horribilis) feeding on Lyngby's sedges (Carex lyngbyei) an important food source with high crude protein content in spring, Khutzeymateen Grizzly Bear Sanctuary, Br...

Eric Baccega / Grizzly bear (Ursus arctos horribilis) feeding on Lyngby's sedges (Carex lyngbyei) her most important food source with high crude protein content in spring, Khutzeymateen Grizzly Bear Sanctuary, Briti...

Eric Baccega / Grizzly bear (Ursus arctos horribilis) female feeding on Lyngby's sedges (Carex lyngbyei) her most important food source with high crude protein content in spring, Khutzeymateen Grizzly Bear Sanctuary...

Eric Baccega / Grizzly male (Ursus arctos horribilis) feeding on Lyngby's sedges (Carex lyngbyei) his most important food source with high crude protein content in spring, Khutzeymateen Grizzly Bear Sanctuary, Briti...

Eric Baccega / Grizzly male (Ursus arctos horribilis) feeding on Lyngby's sedges (Carex lyngbyei) his most important food source with high crude protein content in spring, Khutzeymateen Grizzly Bear Sanctuary, Briti...

Eric Baccega / Grizzly bear (Ursus arctos horribilis) female feeding on Lyngby's sedges (Carex lyngbyei) her most important food source with high crude protein content in spring, Khutzeymateen Grizzly Bear Sanctuary...

Jabruson / Sun-dried fish provides many families with a readily available supply of protein and a product to sell at local markets, Gamba, Gabon

SINCLAIR STAMMERS / Cyanobacterium / Blue green algae (Spirulina platensis) which is used as a health food because of its high protein content. Nomarski photomicrograph

Simon Colmer / Lacewing (Chrysopidae) eggs hanging from tulip petals on protein stalks,

Piotr Naskrecki / Unidentified Cockroach on right, eating old cuticle on left after molting, recovering protein and carbohydrates shed during molting, Costa Rica

Luiz Claudio Marigo / Caboclo family with their bull, alternative source of protein, Amazonia, Brazil

Philippe Clement / Chacma baboon baby baboon killed by dominant male for protein Kruger NP S Africa

Colin Monteath / Antarctic fish on ice, their blood contains glyco-protein that acts as anti-freeze, Port Lockroy, Antarctica

Emanuele Biggi / Panther flying frog (Rhacophorus pardalis) female depositing eggs in nest made of protein rich mucus hanging from leaf, Kubah National Park, Sarawak, Borneo.

Emanuele Biggi / Panther flying frog (Rhacophorus pardalis) females depositing eggs in nest made of protein rich mucus hanging from leaf, Kubah National Park, Sarawak, Borneo.

Eric Baccega / Keeper (Mrs. Lyu Riuqing) preparing high protein food mixed with honey for the female Giant panda (Ailuropoda melanoleuca) Huan Huan, Beauval ZooPark, France. 7 August 2021.

Eric Baccega / Keeper (Mrs. Mao Min) preparing high protein food mixed with Chinese herbs made from tea for the female Giant panda (Ailuropoda melanoleuca), Beauval ZooPark, France. 4 August 2021.

Eric Baccega / Keeper (Mrs. Mao Min) preparing high protein food mixed with Chinese herbs made from tea for the female Giant panda (Ailuropoda melanoleuca), Beauval ZooPark, France. 4 August 2021.

Eric Baccega / Keeper (Mrs. Mao Min) preparing high protein food mixed with Chinese herbs made from tea for the female Giant panda (Ailuropoda melanoleuca), Beauval ZooPark, France. 4 August 2021.

Jeff Vanuga / Grizzly bear (Ursus arctos horribilis) digging out miller moths which are a high source of protein on a high elevation scree slope in the Bridger-Teton National Forest, Wyoming, USA. June.

Jeff Foott / Maasai woman collecting blood from venous puncture on neck of cow. Traditionally blood is used to add protein to the diet, especially of the sick. Maasai Mara National Reserve, Kenya. 2007.

Jeff Foott / Man drinking blood collected from venous puncture of cow. Traditionally blood is used to add protein to the diet, especially of the sick. Maasai Mara National Reserve, Kenya. 2007.

Nigel Cattlin / Field bean (Vicia faba) dried seeds for planting

Nigel Cattlin / Field faba / Fava bean (Vicia faba) crop variety with white flowers, Berkshire, June

Nigel Cattlin / Green, mature soybean (Glycine max) pods on plants with green leaves, Louisiana, USA, October

Nigel Cattlin / Green, mature soybean (Glycine max) pods on plants with green leaves, Louisiana, USA, October