Palpal bulb
![Male Cheiracanthium mildei showing the enlarged and darker palpal bulbs at the end of the pedipalps](/Images/godic/202501/16/Cheiracanthium_mildei_male4810.jpg")
![Left palpal bulb of a male Thaida chepu: 1 – from the right (side nearest the mouth); 2 – from the underside; 3 – from the left (side away from the mouth)bH – basal hematodocha; Cb – cymbium; E – embolus; HSt – hook of subtegulum; mA – median apophysis; mH – median hematodocha; PSt – process of subtegulum; St – subtegulum; Te – tegulumSee text for further explanation.](/Images/godic/202501/16/Thaida_chepu_male,_palp_morphology_cropped4811.jpg")
![Simple palpal bulb of Unicorn catleyi, a member of the Haplogynae group of spiders](/Images/godic/202501/16/Unicorn_catleyi_copulatory_bulb4811.png")
![](/Images/godic/202501/16/PlatycryptusUndatusFemale4811.jpg")
The two palpal bulbs or palpal organs are the copulatory organs of a male spider. They are borne on the last segment of the pedipalps (the front "limbs" of a spider), giving the spider an appearance often described as like wearing boxing gloves. The palpal bulb does not actually produce sperm, being used only to transfer it to the female. Palpal bulbs are only fully developed in adult male spiders and are not completely visible until after the final moult. In the majority of species of spider, the bulbs have complex shapes and are important in identification.