Spinner dolphins engage in non-monogamous sexual reproduction
when they reach the age of sexual maturity. For female Spinners, the age of
sexual readiness varies from four to seven years old, whereas males vary between
seven to ten years. Dolphins are very social, intimate animals, and this is
demonstrated in many different physical interactions. During these mating
occurrences, the animals seem to frequently breech and make much more sound than
usual. Besides the physical behaviors, dolphins also take part in purely sexual
behaviors with one another. Common sexual behaviors may include stroking each
other with their fins or flukes, belly-to-belly rubbing, or even inserting beaks
into the genital slits of the mate. Once the individual is sexually alert and
ready, it will give off chemicals that the mate can taste. Usually these shared
interactions will be quite extensive, but on the other
hand the actual passage of sperm into the female is extremely
fast. Male Spinner dolphins have a very high sperm count, so although sexual
intromission may only last up to one minute, it can be repeated many times.
Once the female is pregnant, the gestation period usually lasts about 10.5 months. The mother will give birth to one calf, tail first, and immediately escort it to the surface for its first breath. The calf, on average, is about 32 inches long and will begin nursing for up to three years in some cases. The relationship between the mother and the calf seems extremely important in this species, and clearly shows concern for the protection and importance of learning in the young Spinners. The fathers do not seem to have such a principal connection with the calf during its early years.
This page was created by Sally Johnson