The trunk is a unique anatomical organ found in several groups of animals. Most often, the trunk is a long, movable appendage of the anterior part of the body that performs a variety of functions: from food capture to breathing and touching. Below is an overview of the main animals with a trunk, as well as real stories of people studying these amazing creatures.

1. Proboscidean mammals (order Proboscidea)

This is the most well-known group of animals with a trunk. It includes:

• African savanna elephant (Loxodonta africana) — the largest living representative. The trunk is formed by the fusion of the upper lip and nose, contains about 40,000 muscles, and has no bones. It is used for breathing, food capture (twigs, fruits), drinking, communication, and even for dust baths.
• African forest elephant (Loxodonta cyclotis) — smaller in size, but the trunk also performs the same functions as its savanna counterpart.
• Asian elephant (Elephas maximus) — differs in that it has only one finger-like projection at the end of the trunk (two in African ones). The trunk is used for stripping leaves, gathering fruits, and rinsing with water.

Extinct proboscideans

• Mammoths (Mammuthus) — had a long, curved trunk adapted for eating grass and twigs in cold steppes.
• Deinotheres (Deinotherium) — ancient relatives of elephants, with a downward-curved lower jaw and a presumably shorter trunk.

2. Insects with a proboscis

The proboscis (the mouthpart) in many insects is a modified lower lip or jaws. It is used for feeding on liquid food:

• Butterflies — have a long, coiling proboscis (formed by fused jaws) that they use to feed on nectar from flowers.
• Flies (for example, houseflies) — their proboscis (labellum) has a spongy structure for absorbing liquid food.
• Mosquitoes — the females have a piercing-sucking proboscis for piercing the skin and sucking blood.
• Bees and wasps — the proboscis (tongue) is used for collecting nectar, its length varies depending on the species.
• Aphids and mealybugs — have a piercing-sucking proboscis for piercing plants and sucking sap.

3. Cephalopod mollusks

In some cephalopod mollusks, the trunk is called the elongated part of the body:

• Nautiluses — have a funnel (siphon) that performs the functions of a reactive movement, but it is sometimes called a trunk due to its elongated shape.
• Squid and octopuses — their trunk can be called the elongated part of the mantle or tentacles used for capturing prey (but this is more of a homologous structure rather than a true trunk).

4. Some fish

• Sea horses — their elongated snout is often called a trunk. It is used for suctioning small food (plankton) through rapid head movement.
• (family Syngnathidae) — have a tubular snout that serves for suctioning prey.
• (or gнатонемусы) — African freshwater fish from the order Osteoglossomorpha, with a lower jaw elongated into a long 'trunk' for searching for food on the bottom.