A flaccid elephant penis is normally sheathed between the hind legs. As the penis starts to engorge it may partially extrude, still flaccid. A semi-erect penis is almost fully engorged and extrudes forward from the sheath and downward toward the ground. During a full-erection the tip of the penis twitches for several seconds, curving upward toward the belly, forming an S-shape. The term Penis-Erection refers to both semi- and full-erections.
When a non-musth male elephant urinates he fully extends his penis and usually, thereafter, obtains a semi-erection, which may lead to a full-erection. Males in musth typically Urinate with the penis still sheathed. Male infants and calves usually obtain erections when they Suckle, and both young and adult males sometimes obtain semi- and full-erections when they are engaged in Sparring activities, especially when these include Mounting.
References: Poole 1982: 49, 57, 108, 109, 133, 142; Poole & Granli 2003; Poole & Granli 2011. (Full reference list)
This behavior occurs in the following context(s): Advertisement & Attraction, Calf Nourishment & Weaning, Courtship, Maintenance, Social Play