Calathea is a genus of the plant family that also includes plants that are commonly called "prayer plants" - Marantaceae. There are lots of varieties, and we're going to run through them below. Both Calatheas and Marantas have a very interesting behavior - they exhibit nyctinasty - or their leaves move from day to night - it's a part of their circadian rhythm!
Watering: Calathea are sometimes very sensitive to very hard tap water, and often prefer to be watered with either distilled water, or at least water that's left out for a few days to dechlorinate. They like to be slightly damp, and not dry out 100%. Test the soil with your finger, it should be dry halfway down, and moist at the bottom. They LOVE to be misted, or to sit near a humidifier. Some of them are more sensitive than others, like the White fusion - who is a KNOWN brat, or the orbifolia, who loves to get little brown tips.
Light - They prefer a relatively bright window spot, especially the white fusion (any plant with more white on the leaves has less chlorophyll - and usually loves more light!).
Pets: - Calathea are usually pet friendly!
How do I know if they're not happy? - wilted, or curled leaves - underwatered usually! Yellow leaves or a black base - Usually over watered! Leaf spots - usually from minerals in the tap water. Use distilled water.
Check out these Calathea options below!