Rhysida is a genus of insects commonly known as whip spiders or tailless whip scorpions. They belong to the arachnid family and are not true spiders or scorpions. Rhysida insects have elongated bodies with long, whip-like appendages at the front, which they use to sense their surroundings. They are nocturnal creatures and are found in tropical and subtropical regions, often dwelling in dark and humid environments such as caves or leaf litter.