North American River Otter Reproduction
In order to increase its population, the River Otter needs to reproduce. They practice heterosexual reproduction which requires a male and a female. To perform fertilization, the female and male sex cells (egg and sperm, respectively) meet and grow into an embryo. This embryo contains genes from both parents. Otters have 38 diploid chromosomes. Female eggs are created through oogenesis, while male cells (sperm) are made through spermatogenesis. An egg is released when it becomes mature into the oviduct. This is where the sperm and egg meet and get fertilized. In order for fertilization to occur, sperm needs to be made and released. Sperm is created in the testicles and meets with other liquids from the prostate to create semen. Semen exits the penis through the urethra and enters the female through the vagina. In order to meet the egg, the sperm needs to pass through the cervix. When fertilization occurs, the fetus grows in the uterus of the female. The gestation period of the otter is 9.5-12.5 months. A typical litter contains 2-3 pups but can range from 1-6 babies. Otters are weaned by 120 days of living, however, they stay with the mother until her next litter. Females and males are sexually mature at 1 year old but usually mate around 2 years. Mating typically occurs in water around late winter (March and April).