North American River Otter Reproduction
The North American River Otter's reproductive organs are similar to those of other small mammals. The male reproductive system contains a penis, testes, scrotum and more while the female reproductive system contains a vagina, ovaries, etc. The female otter's ovaries increase in size as maturation occurs. Both male and female otters reach sexual maturity when they are two or three but they may not successfully reproduce until they are about five to seven years old.
River otters usually mate in the months of March and April. When a female otter is in her most fertile state it is referred to as estrus. Estrus can last anywhere from 20-56 days. Usual mating rituals commence with rough play such as running, swimming, diving, and chasing.
Fertilization is internal with the otters meaning the male releases the sperm inside the female. While mating a male otter sometimes bites a female by the scruff of her neck or on her nose, leaving a noticeable mark. Each gamete contains 19 chromosomes to make a total of 38. All in all, the North American River Otter has quite an interesting reproductive system.
River otters usually mate in the months of March and April. When a female otter is in her most fertile state it is referred to as estrus. Estrus can last anywhere from 20-56 days. Usual mating rituals commence with rough play such as running, swimming, diving, and chasing.
Fertilization is internal with the otters meaning the male releases the sperm inside the female. While mating a male otter sometimes bites a female by the scruff of her neck or on her nose, leaving a noticeable mark. Each gamete contains 19 chromosomes to make a total of 38. All in all, the North American River Otter has quite an interesting reproductive system.
Male Reproductive System
Female Reproductive System
(although the image is of a cat, the female otter's system is similar)
Mating Video
Development
The North American River Otter goes through stages of maturation. Beginning with newborn stage and then mature stage. River otters reach maturity around two years of age. The life expectancy for an otter is about 8-9 years. Interestingly, after the egg is fertilized it goes through a stage when the embryo becomes inactive known as delayed implantation. The gestational period for an otter is approximately 63-65 days. North American River otters typically have 1 or 2 offspring at a time. Parental care typically lasts for 1 year-1 1/2 years or until the next mating season comes along.
Asexual Reproduction vs Sexual Reproduction
Asexual reproduction is when, through mitosis, an organism creates an exact copy of itself. In asexual reproduction another partner is not needed, it is done through a single organism. Organisms such as bacteria reproduce asexually. Mitosis goes through multiple stages: prophase, anaphase, metaphase, and telophase. Meanwhile, sexual reproduction occurs between two organisms. Sexual reproduction occurs when gametes- sperm and egg- join inside the fallopian tubes of a mammal. The gametes are created by meiosis. The fertilized egg continues to grow in the ovary until ready for birth. The stages of meiosis are interphase, prophase, metaphase, anaphase, telophase, and cytokinesis.
Genes & Chromosomes
A gene is a name given to a specific, heritable subunit of DNA in the body. Different genes bring out different traits since they each genes have different "codes". A chromosome is a tightly coiled shape containing genes. When reproducing sexually each cell of the offspring contains one set of the mothers chromosomes and one set of the fathers.
Sources
1.http://www.biology-online.org/dictionary/Linked_genes
2.http://www.news-medical.net/health/Genes-What-are-Genes.aspx
3.http://en.wikipedia.org/wiki/Gene
Sources
1.http://www.biology-online.org/dictionary/Linked_genes
2.http://www.news-medical.net/health/Genes-What-are-Genes.aspx
3.http://en.wikipedia.org/wiki/Gene
Gametes
Gametes are specific cells that are involved in reproduction. When gametes unite during sexual reproduction they form a zygote. Gametes are also known as sperm and egg cells, which are formed by meiosis- specifically spermatogenesis and oogenesis. Sperm cells are special because they have a special feature, a flagella. A flagella is a tail like projection from the cell helping it to swim. Gametes are haploid cells and eventually when they join, form a diploid cell.
Sources
1.http://biology.about.com/od/geneticsglossary/g/gametes.htm
Sources
1.http://biology.about.com/od/geneticsglossary/g/gametes.htm