The animal which most biologists call "daddy-long-legs", is a spider, Pholcus phalangioides, which belongs to the spider family Pholcidae, order Araneida, class Arachnida. The CSIRO handbook follows this usage: Naumann, Ian 1993. CSIRO Handbook of Australian Insect Names: common and scientific names for insects and allied organisms of economic and environmental importance. CSIRO.

Pholcid spiders are araneomorph spiders which kill and digest their prey using venom. However there is no scientific basis for the urban myth that daddy-long-legs are the most venomous, poisonous or toxic spiders in the world. Their venom has never been tested and certainly not on humans!!