The testes are located inside the abdominal cavity. They are tennis ball sized structures just posterior to the kidneysThe elephant penis is the muscular type similar to that of horses and humans. The length of penis is about 2 meters, and it is S-shaped. The other organs involved in the male elephant reproductive system are the seminal vesicles, the sperm storage organ, and prostate gland, the ampullae and the bulbourethral glands.
Figure 9. The male elephant reproductive system (modified from Hildebrandt et al., 2006)
Like a cow or mare, the female elephant has bilateral uterine horns. The ovaries are located behind the kidneys. The genital canal is 68-88 centimeters long and consists of a vagina, vaginal os and vestibule. The vulva position is between the inguinal regions, ventrally, which is different from most other mammals which have the vaginal oss located perineally under the tail. The clitoris lays in the vulva and is about 40 centimeters long, about the same length as thevulva. The two mammary glands are located pectorally between the forelegs. The placenta of the elephant is zonary. The gestation period of the elephant is very long, about 17-22 months. A male calf has a longer gestation period,( average 21-24 month) compared to a female calf (17-23 months).
Figure 10. The female elephant reproductive system (modified from Hildebrandt et al., 2006)
Special sense organs
The structure of elephant eye is similar for both species. The elephant does not have a lacrimal apparatus, but the hardarian gland can observed closeto the third eyelid. The gland secretion plays theimportant role of preventing drying of the eye. The third eyelid is well developed and strong to protect the globe of the eye . The ppupil and iris are circular shaped and colors of iris vary between greenish-brown and blue. The visual ability of elephants is limited because of the eye, ear and trunk locations and the limited mobility of the eye..
The ear of the elephant is a second highly sensitive organ The elephant can hear at 12,000 Hertz in the upper limit, compared tobats (80,000 Hertz), dogs (40,000 Hertz) and humans (20,000 Hertz). On the other hand, elephants can hear and produce sound which has a long wave length, 14-16 Hertz, below the hearling range of the human ear (20 Hertz). Therefore elephant communication is not entirely audible to humans. They can communicate to other elephants at a great distance using these ultrasonic wavelengths.. The functions of the ear include acoustic detection, balance, thermoregulation and information transfer. The constriction and dilatation of blood vessels in the elephant ear are controlled by signals from nerves, which are sensitive to temperature. We can estimate an elephants age from the ear fold, which progresses in size with age.
The nose or trunk is the smelling organ of the elephants, and is associated with the special sensory organ called the vomeronasal organ located on the palate of the mouth. The vomeronasal organ structure consists of two small pits connected by numerous nerve endings which transmit smelling sensation to the brain. The vomeronasal organ is a highly sensitive organ for smell. When elephants want to detect an odor, they raising and wave their trunk in the air to better inhale the smell. They can find and locate water sources about 50 kilometers away, and can detect the reproductive status of the other elephants from a long distance, especially males detecting female elephants in estrous.
Figure 11. The opening of a vomeronasal organ of the elephant