A daddy-longlegs possesses six eyes, including two vestigial pairs
New research on daddy longlegs (specifically harvestmen, not spiders) suggests they possess six eyes, including pairs that appear vestigial, prompting debate over whether such structures truly lack function or simply have roles humans haven’t yet identified. Commenters explore how evolution can favor consolidating sensory functions into fewer organs, likening this to modern sensor trade-offs in technology such as Tesla’s move toward camera-only systems. A substantial part of the conversation also focuses on the confusing common names for long-legged arthropods and insects—harvestmen, cellar spiders, and crane flies—which vary by region and underscore the value of precise scientific naming.
Vestigial eyes and evolutionary function
- Some argue it is premature to call the extra eyes “vestigial” without testing for sensitivity to other spectra (IR, UV, etc.) or stimuli; they claim evolution would not retain a completely useless structure.
- Others counter that “vestigial” explicitly means a structure that once had a function but no longer does, or has a much-reduced function.
- A side debate notes that “vestigial” is often used when a function is simply not yet known, with the appendix cited as an example where a role was later proposed.
What “daddy longlegs” refers to
- Major confusion arises because “daddy longlegs” is applied to multiple groups:
- Harvestmen (Opiliones) – subject of the article.
- Cellar spiders (Pholcidae) – true spiders with webs.
- Crane flies – long-legged flies with wings.
- Different regions (US, UK, PNW, Midwest, California, Alaska, Germany, etc.) use “daddy longlegs,” “harvestmen,” “cellar spiders,” “mosquito hawks/eaters,” “gollywoppers,” “candleflies,” “Opa Langbein,” and more, often inconsistently.
- Several commenters only learned from the thread that other animals share this common name, leading to past misidentifications.
Taxonomy and scientific naming issues
- Scientific (Latin) names are presented as a solution to common-name collisions, though some note that even Latin names can be historically careless.
- An example is the genus Phalangium for harvestmen, which one commenter says was misapplied by Linnaeus relative to Aristotle’s original descriptions.
- A project (TaxonWorks / wcolite.com) is mentioned as curating nomenclature for these groups.
Ecology, behavior, and human attitudes
- Many describe Pholcidae as harmless “friend-spiders” that eat more dangerous spiders and pests; they are often tolerated in homes.
- Their webs are said to be non-sticky, extended over time, and sometimes built on abandoned webs; spiders may relocate if webs are repeatedly destroyed.
- Harvestmen (Opiliones) are reported to have stink glands and can shed twitching legs when handled; some people detect a musky or mint-gum-like odor, others never notice a smell.
- Emotional responses vary from fascination to strong arachnophobia and childhood trauma.
Sensory systems and Tesla analogy
- One commenter links the evolution of multiple/reduced eyes to reptiles’ “third eye” used as a light sensor for diurnal cycles.
- A long subthread compares consolidating sensory modalities in animals to Tesla’s move toward camera-only systems:
- One side claims extra sensors were needed only for initial mapping, later dispensable.
- Others say removal was cost-driven, the world changes so maps are never “done,” and vision-only systems may be inherently limited.
- There is disagreement over whether Tesla ever truly relied on LIDAR, how much mapping is used, and whether vision-only FSD is close to “there.”
- Some think vision-only could still surpass human ability via better coverage and processing; others argue multiple sensor types are essential for robust autonomy.
Cultural, meta, and humorous tangents
- Jokes about software-style naming (“DaddyLonglegsManager,” “DLL hell”) and the difficulty of naming things appear throughout.
- Several light comments reference Horizon Zero Dawn, spider phobias, infrared “Spidey senses,” and image memes about “who ate the middle out of the daddy longlegs.”
- A small meta-thread laments rising “noise” and the cyclical migration between online communities.