The penis of the

Opiliones The Opiliones (formerly Phalangida) are an order of arachnids colloquially known as harvestmen, harvesters, harvest spiders, or daddy longlegs. , over 6,650 species of harvestmen have been discovered worldwide, although the total number of ext ...

(harvestmen) is an intromittent organ that is not present in other

arachnid Arachnida () is a class of joint-legged invertebrate animals (arthropods), in the subphylum Chelicerata. Arachnida includes, among others, spiders, scorpions, ticks, mites, pseudoscorpions, harvestmen, camel spiders, whip spiders and vinegar ...

s. It consists of a long shaft (the truncus) and a terminal capsule called a

glans The glans (, plural "glandes" ; from the Latin word for "acorn") is a vascular structure located at the tip of the penis in male mammals or a homologous genital structure of the clitoris in female mammals. Structure The exterior structure ...

, containing a stylus and ejaculatory duct. It may have from one to three muscles, or none as in the specialized lineage

Grassatores The Grassatores are the most diverse infraorder of the Laniatores. It includes over 3,500 species distributed mainly in the tropicsKury, A.B.(2003). Annotated catalogue of the Laniatores of the New World (Arachnida, Opiliones). '' Revista Ibéri ...

, where the penis is operated by

haemolymph Hemolymph, or haemolymph, is a fluid, analogous to the blood in vertebrates, that circulates in the interior of the arthropod (invertebrate) body, remaining in direct contact with the animal's tissues. It is composed of a fluid plasma in which ...

pressure. In some members of the Cyphophthalmi, the structure has been termed a "spermatopositor". This denomination refers to a superficial similarity ( analogy) with

vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () (chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with c ...

penis A penis (plural ''penises'' or ''penes'' () is the primary sexual organ that male animals use to inseminate females (or hermaphrodites) during copulation. Such organs occur in many animals, both vertebrate and invertebrate, but males d ...

es and does not have any

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

relationship with it.

References

External links

Opiliones reproductive anatomy
Dr. Jefferey Schultz, University of Maryland
Harvestman Spider penis, ''Thelbunus mirabilus''
- Australian Museum {{Opiliones-stub Arachnid anatomy Harvestmen Sex organs Penis