Octopuses are marine creatures known for their intelligence. A common question concerns their sexes and how to distinguish them. Octopuses have distinct male and female individuals, exhibiting sexual dimorphism.
Distinct Sexes in Octopuses
Octopuses possess two sexes, with males having a single testis and females an ovary, both located posteriorly. Reproduction requires the interaction of two individuals. This sexual dimorphism contributes to genetic diversity within octopus populations.
Identifying Male and Female Octopuses
The most reliable way to differentiate between male and female octopuses is by observing a specialized arm on the male called the hectocotylus. This modified arm is typically the third arm on the right side. It has a suckerless tip and a distinct groove for transferring sperm. In some species, this arm may also be noticeably shorter than the others and often kept curled up.
While the hectocotylus is the primary indicator, other differences can be observed, though these vary by species. Females are often larger than males, a size disparity that can be extreme in some species, such as the blanket octopus where females can be over 50 times larger. This size difference is not a universal rule. Females have suckers extending to the tip of their arms, unlike the male’s hectocotylus.
The Reproductive Process
Octopus reproduction involves transferring sperm packets, known as spermatophores, from the male to the female. The male uses his hectocotylus to deliver these spermatophores into the female’s mantle cavity. Depending on the species, the male might insert the arm directly or, in some cases, detach the hectocotylus, which then moves to the female. Mating rituals can vary from subdued affairs to more elaborate courtship displays involving changes in skin texture and color.
After receiving the spermatophores, the female stores them until she is ready to lay her eggs later. When the time comes, she typically finds a sheltered location, such as a den, where she lays her eggs. Octopus eggs are often laid in strings or clutches, which the female attaches to a surface. The number of eggs can range from thousands to hundreds of thousands, depending on the species.
Life Cycle and Parental Care
Once the eggs are laid, the female octopus dedicates herself entirely to their care. She tirelessly cleans the eggs, removing debris, and uses her siphon to fan them with fresh, oxygenated water. This brooding period is crucial for the eggs’ development and can last from a few weeks to several months, influenced by factors like water temperature. In some deep-sea species, this brooding can extend for an exceptionally long time, with one observed case lasting over four years.
During this entire brooding phase, the female typically ceases eating, focusing solely on protecting her offspring. This self-sacrificing behavior often leads to a significant decline in her health. For most octopus species, reproduction marks the end of their lives; males usually die within a few months after mating, while females perish shortly after their eggs hatch. The newly hatched octopuses, often called paralarvae, are typically small and planktonic, drifting with ocean currents before settling into a more independent existence.