A large leech slithers over a man's arm.

A large leech sucks blood from a man's arm.

A finger pokes at a leech as it crawls across skin.

A leech sucks blood from a human arm.

A large leech slithers along a man's arm.

A leech sucks blood from a man's arm.

A large leech sucks blood from a man's arm.

A leech slinks along a man's arm.

A leech slithers over a sandaled foot underwater.

A giant leech slithers across a person's hand.

A researcher maneuvers a giant leech on his leg.

A leech slithers over a man's leg.

- Fruiting body of a Cordyceps fungus growing out of a parasitized moth in the rainforest, Ecuador. Thread-like spores (ascospores) are being released from the ascocarp which will drift away and infect a new insect host.

Leech removed whilst sucking blood from human skin, Indian rainforest

Close Up push-in push-out - A rat and a snail host parasitic worms in a computer-generated animation.

Close Up push-out - Parasitic worms hatch and travel through a bloodstream in a computer-generated animation.

Some species of wasp lay eggs on living animals such as this caterpillar. The wasp typically injects venom, anti-immune chemicals and digestive enzymes into the caterpillar when it lays its eggs. When the eggs hatch, the larvae feed on...

MS Indian Elephant, Elephas maximus, leech feeding on elephants leg, Western Ghats, India

Fern and Moss growing on tree trunk. Pacific Northwest USA.

Extreme Close Up push-in - Eye drops reveal parasites on an eye with a contact lens in a computer-generated animation.

Viruses

T/L Dodder (Cuscuta sp.) BCU shoot creeping up host plant, United Kingdom

Anopheles Mosquito, ECU head, antennae and proboscis, removes proboscis from skin

MS T/L view of Rabbit decomposing, United Kingdom