Suzi Eszterhas / Red-shanked douc langur (Pygathrix nemaeus) infant sucking thumb while caretaker holds it. Animal was rescued from illegal wildlife trade, Endangered Primate Rescue Center, Cuc Phuong National Park, V...

Luke Massey / Giant otter (Pteronura brasiliensis) feeding on a catfish (Loricariidae) with Cocoi heron (Ardea cocoi) scavenging remnants, Rio Cuiaba, Brazil

Jaymi Heimbuch / African Elephant (Loxodonta africana) orphaned calves with keeper, David Sheldrick Wildlife Trust, Nairobi, Kenya

Andy Rouse / Mountain gorilla (Gorilla beringei) baby held by mother, Rwanda

Piotr Naskrecki / Yellow Fever Mosquito (Aedes aegypti) female feeding on human blood, Gorongosa National Park, Mozambique

Fiona Rogers / Japanese Macaque (Macaca fuscata) baby sucking its toe in a geothermal spring, Jigokudani Monkey Park, Japan

Anup Shah / Bonobo (Pan paniscus) baby aged 3 months sucking it's mother's finger, Lola Ya Bonobo Sanctuary, Democratic Republic of Congo. October.

Alex Hyde / Cleg fly / Horsefly (Haematopota pluvialis) sucking blood from human.

Nick Upton / Cleg fly / Horsefly (Haematopa pluvialis) sucking blood from photographer's arm, Wiltshire pastureland, UK, June.

Stephen Dalton / Horsefly (Tabanus sudeticus) feeding on human skin, UK

Kim Taylor / Mosquito (Aedes punctor) female resting after sucking blood from human arm. Sequence 4/4

Kim Taylor / Mosquito (Aedes punctor) female sucking blood from human arm. Sequence 3/4