Surprise! “Daddylonglegs” Are Not Spiders
By Chris Williams on November 23, 2015.
A friend told me that the daddylonglegs spiders that we’re seeing on our front porch are not spiders at all. Is that true? They have 8 long legs and they sure look and act like spiders. J.M., Goffstown, NH
It is true that they’re not. Both spiders and the familiar daddylonglegs belong to the large arthropod class Arachnida which also includes related arthropods such as mites, ticks, and scorpions. But within that class, spiders belong to the Order Araneae, while daddylonglegs belong in the Order Opiliones, a group known as harvestmen. A classification technicality sure, but spiders and harvestmen are in different groups because they have many differences.
How Daddylonglegs Differ From Spiders
Daddylonglegs: (1) have only two eyes, compared to the usual 8 in spiders, (2) their head, thorax, and abdomen are joined together, appearing to be one big, rounded segment rather than separated into a cephalothorax and abdomen as in spiders, (3) eggs are laid in the ground rather than in an egg sac deposited in or near a web, (4) they cannot produce silk; although not all spiders spin webs, they are all capable of producing silk, (5) they do not have venom glands or fangs to subdue prey, and therefore cannot bite people.
Fun Facts About Daddylonglegs
There are more than 6,500 species of harvestmen, worldwide. Like spiders, some daddylonglegs are predators on insects, but others feed on bird droppings (ew!) or plant juices. Like house centipedes, their long legs easily break off and may continue to twitch afterwards. There are actually some species of daddylonglegs that have short legs. Daddylonglegs do not produce silk so they have no webs. Most species can live for a year or two.
Daddylonglegs are rarely found in living areas. They occupy the same kinds of dark, sheltered, damp places as camel crickets around homes. Harvestmen can be seen outside under eaves, or in window frames, in damp crawlspaces, basements, or garages. Sometimes you will find large numbers of daddylonglegs clustered together under eaves, probably as a mating aggregation. In their natural habitat, they are found under logs and rocks.
To summarize: the creatures that we most often refer to as daddylonglegs are not spiders. But there is one group of true spiders that used to be known as cellar spiders and are now called “daddylonglegs spiders.” And to really confuse the issue, in some regions, large, long-legged crane flies are also called daddylonglegs!
Photo credit: Chris Alban Hansen / Foter / CC BY-SA