Walking on one leg is called unipedalism and we can only see this in a handful of species. Aside from amputations and genetic defects, most species have at least two legs.
In this article, we’ll be listing down the animals with one leg.
- Slugs
- Snails
- Sea Hares
- Limpets
- Nudibranchs
- Abalones
Topics
1. Slugs
Scientific name (class): Gastropoda
Slugs are an informal grouping with the class of gastropods, and the name refers to any terrestrial gastropod without a shell. We mostly consider slugs to be snails without a shell (often called a ‘house’).
Snails are animals with a single foot on the bottom of their body, which is why they move so slowly. They can only move by contracting their muscles rhythmically (similar to worms).
In order to prevent damage and make it easier to move, slugs secrete mucus, which is why they’re often slimy.
2. Snails
Scientific name (class): Gastropoda
Snails are essentially slugs with hard shells that they can retreat into when danger arises. Just like slugs, they only have one foot, and they’re probably the most well-known animal with one leg.
The snail moves by contracting its muscles and secreting mucus to lubricate the ground (which is why they leave a trail wherever they go).
Slugs and snails are both very slow, never moving quicker than 0.013 meters per second or about 0.04 feet per second.
It is believed that snails are slower than slugs because of the weight of their shell.
3. Sea Hares
Scientific name (clade): Anaspidea
Even though they’re related to land snails, sea hares are much larger animals, with some of them weighing up to 30 pounds and reaching 30 inches in length.
These sea animals with one leg crawl most of the time, but they also have wing-like flaps on their sides which they use to swim away when threatened.
On top of swimming away, they’ll also release a red or a purple fluid to mask their escape.
4. Limpets
Scientific name (clade): Patellogastropoda
Limpets are animals with a single leg, but unlike all the other species so far, they don’t move just by contracting muscles. Since they live in the sea, they have to attach themselves firmly to the surface. Otherwise, they could be thrown off by waves.
They have adhesive mucus allowing them to apply suction, and they only move when the waves around them allow that. A limpet’s suction capabilities are impressive, as they can be near impossible to remove from a rock (unless you crush it).
5. Nudibranchs
Scientific name (order): Nudibranchia
With over 3000 species of nudibranchs in the world, we now know that they’re animals with underdeveloped movement capabilities. These sea animals with a single foot can make slight modifications to it, based on the kind of surface they’re covering.
Nudibranchs mostly move on their foot, while their swimming abilities can be described as limited, as they can only cross small distances.
They’re incredibly diverse as a species, with hundreds of different colors and patterns showing. Some nudibranch species are apparently capable of camouflage. However, because of their bright coloring, predators can spot them very easily.
6. Abalones
Scientific name (genus): Haliotis
These unipedal animals are sea snails with hard shells, the largest of them being 12 inches long. They also have a single foot, and they use it to cling to rocks, similar to limpets (although abalones are usually much heavier).
Their movement is very slow, as they have to simultaneously move and make sure they’re not blown away by waves. Abalones, therefore, spend large periods of time stuck in a single spot.
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