One could argue that the slowest animals are those that spend their lives rooted to one spot: barnacles, sponges and mussels, among others. But these are aquatic, and don't need to travel because the currents bring them what they need.
What is the slowest animal on land?
On land, animals must actively go and find what they need. And if we confine ourselves to mobile animals big enough to be seen without a microscope, then slugs and snails must be in the, erm, running for slowest animals.
The winner at the 2019 World Snail Racing Championships only clocked 3.4mm per second (0.012kph). Even tortoises seem like hares in comparison.
What is the slowest mammal?
For the title of slowest mammal, sloths, which navigate the treetops at about 0.24kph, will always be hard to lose to, although they are faster in water than on land. Their gait is designed for efficiency rather than speed, because their leafy diet gives them little energy to play with.
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