Depends which one you mean.
Cellar Spider - Pholcus phalangioides
Crane Fly - Tipula paludosa
Harvestman - Phalangium opilio
The scientific name for a daddy long leg is Pholcus phalangioides.
It depends what species you are referring to. There is the crane fly. It's scientific name is Nephrotoma.You are probably referring to the cellar spider or the harvestmen. The cellar spideris most likely the spider you are talking about. It's scientific name is Pholcus phalangioides. There harvestmen's scientific name is Hadrobunus grandis.
The daddy long legs is named for its incredibly long legs, which are massive in comparison to its body.
The name daddy-long-legs beginning is unknown. It is suspected to have come from a book by Jean Webster about a girl in an orphanage whose benefactor is a tall man whom has long legs and she calls him Daddy Long Legs.
Daddy long legs or Pholcus phalangioides
Cranefly
Daddy long legs
None of the species know by the common name "daddy long legs" have gills, nor do they live in water and have need of them.
Another name for the "Crane fly" is the "Daddy long legs"
It is the common name for a really long legged spider (arachnid).
harvestman spider
Daddy Long Legs, most commonly used in the U.K. In the U.S., Daddy Long Legs typically refers to a kind of spider.