Among mammals, unique to egg-laying mammals (platypus and echidnas).Able to swim forward faster likely improves ability to compete.“Sperm bundles” form when heads bind together as sperm pass through the epididymis (Nixon et al.Suggests that males mate with multiple females.

Male reproductive organs and structures.Females may be four years or older (Grant et al.Both sexes physically able to reproduce in second breeding season after independence, but many begin breeding later (Grant 2007 Grant 2015).After copulation, female becomes solitary for nesting (Thomas et al.In managed care, copulations have occurred over several days.Male moves forward, nuzzling and gripping female’s fur.Courtship behaviors may last less than a minute or half an hour or more, over several days (Grant 2007).Pair swims in a tight circle (Fleay 1944b De-La-Warr and Serena 1999).Male grasps female by tail with bill (Fleay 1994b).Then, male and female grasp each other and roll several times (Grant 2015, and as noted).Male and female dive and swim past each other (Grant 2015 Thomas et al.At first, female avoids male then reduces avoidance (Thomas et al.Searches territory for unmated females (Thomas et al.Male initiates most interactions (Hawkins and Fanning 1992 Grant 2007).Video: courtship behaviors begin at 01:21.Mating rarely observed in the wild (De-La-Warr and Serena 1999 Grant 2015).Social system not well known (Grant 2015).Male venom gland size and male aggression increase during breeding.Thought to be polygynous (needs confirmation with additional studies) (Bino et al.

San diego zoo platypus baby