Range: Asia, Africa, the Americas, Australia and Pacific islands

Habitat: Most terrestrial habitats that support their diet

Size: Up to 4.7 inches (12 cm) when fully extended

Diet: Plants and decaying matter

Threats: Frogs and invertebrates including other slugs

Lifespan: Two years

Transcript:

Today on Animal Fact Files we’re discussing leatherleaf slugs. These invertebrates are named for their leathery mantle and leaf-like shape. The mantle in a slug is the thick, fleshy part that protects their body. In most slugs this looks like a saddle on their back, but in leatherleaf slugs it covers their entire back. Plus, many terrestrial slugs have a respiratory hole called the pneumostome, but leatherleaf slugs don’t have this. Instead, these gastropods have a flattened body with no shell, internal or otherwise.

Although leatherleaf slugs are generally easy to tell apart from other slug families, they’re difficult to tell apart within their own family. Often, the only way to be sure of the slug’s species is by examining its internal genitalia. Leatherleaf slugs are hermaphroditic but have different penis structures depending on the species. Of course, this is invasive and not always accurate. Some leatherleaf slug species can only be determined molecularly. Even individuals in the same species can appear different!

These leathery slugs range from white to brown with an assortment of patterns such as speckles and stripes. Even their maximum size can vary within a single species. The largest leatherleafs reach almost 5 inches, 13 centimeters, long, but many are shorter. These slugs have two pairs of tentacles on their face. The upper pair supports their eyes– these can not be fully inverted such as in other slug species. The anus is located near the front of the body in most terrestrial slugs, but in leatherleaf slugs it’s near the back. So yeah, a weird mantle, no obvious breathing hole, and an oddly placed butthole all help set these slugs apart from others.

There are approximately 100 described leatherleaf slug species. They’re most species diverse in tropical and subtropical areas of Africa and South America but are also found in Asia, Australia, North America, and on Pacific islands. These slugs live in pretty much any terrestrial habitat that supports their diet. They eat a variety of plants and decaying vegetation, and they mostly come out at night. Some leatherleaf slug species are considered pests because they eat human crops such as bananas, beans, coffee, mangoes, peppers, and more. They also carry parasitic nematodes in their bodies such as the rat lungworm which can cause a rare type of meningitis in humans, so it’s not advised to eat them. Frogs, however, can handle these slugs in their diets, so humans deploy frogs to help control leatherleaf slug populations in agricultural settings.

Some leatherleaf slug species are known to self fertilize,a form of asexual reproduction. In sexual reproduction for this family, two individuals swap sperm and each lays a few dozen to about 100 eggs. These are laid in soil and sometimes covered in soil-laden feces to help protect and hide the clutch. The eggs hatch within a week. From there, it takes about half a year for the young slugs to start their own participation in the leatherleaf slug life cycle. Breeding in these gastropods occurs in rainy weather or during the rainy season. On average, they live to be about 2 years old.

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