Snail Snake

Genus Pareas

Reptile

Transcript:

Today on Animal Fact Files we’re discussing snail snakes. They're also known as snail eating snakes, slug snakes, slug eaters– and there's also my personal favorite goo-eaters. This episode is specifically focused on the snail snakes found throughout southeast Asia (Pareas genus), but their classification isn't well defined and has changed within the last decade, so things are a little loosey goosey. There are other snail-eating snakes in other parts of the world. Depending on your source, there are somewhere around 15 to 30 currently described species of slug eating snakes in this genus.

These reptiles have a big, blunt head with large eyes that show off vertical pupils. While that trait is often quoted as an indicator of venomous snakes, these snakes are not venomous– and some venomous snakes have round pupils, so that whole concept is just a myth entirely. Snail snakes have a clearly defined neck, a skinny body averaging about 2 feet, 61 centimeters, long, and a grippy, prehensile tail. These vertebrates are arboreal meaning they live a majority of their lives above the forest floor.

Many snail snakes are endemic with restricted ranges. They live in forests and grasslands, including agricultural areas such as sugar cane fields. They're nocturnal, emerging with their prey. As the name “snail snake" implies, these snakes eat snails, and slugs too, of course. What's more, snail snakes are actually limited to small, squishy meals because of their body shape. They have an asymmetrical jaw for extracting snails out of their shells. Their left jaw may have 17 teeth, but the right side has 25 teeth! This makes it easier for the snake to pull the snail’s soft body out of its shell– at least in the case of snails whose shells spiral to the right. These are known as dextral snails, and they make up the majority of the snail population in areas where snail snakes inhabit.

This is an example of co-evolution. The snakes evolved to more easily eat the right-shelled snails. What's cool about this is that the snails have adapted to the snakes as well! There is often a higher concentration of left-shelled snails in areas where snail snakes occur, although they still don't make up the majority. This is likely a defense against predation from the snail snakes, as the snakes are not as effective at capturing these opposite shelled snails. Of course, snail snakes also eat slugs and insect grubs, so they don't always have to work around an outer shell just to eat a meal.

When snail snakes feel threatened, they coil into a defensive ball. They're eaten by introduced cane toads, and they may also be consumed by larger native reptiles as well as birds of prey. That being said, there's not a whole lot of information on their life history. In captivity, snail snakes are recorded to reach about a decade old, but their life span in the wild is unknown. They lay small clutches of fewer than 10 eggs that take about two months to incubate depending on the species, but that's about all we know. There's still much to learn about these goo-eaters.

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