While the female octopus is known for her end while guarding her eggs, the male’s story is often less understood. His life is equally tied to the act of reproduction, culminating in a final chapter that is just as definitive. The male octopus embarks on a singular, ultimate mission to pass on his genetic material.
Identifying a Male Octopus
Distinguishing a male octopus from a female requires a close look at their arms. One of the male’s eight arms is a specialized reproductive tool called a hectocotylus. In many species, such as the Giant Pacific Octopus, this is specifically the third arm on the right. This modified arm is noticeably different from the others because its tip, known as the ligula, lacks the suckers that typically run the full length of the other arms.
The hectocotylus has a distinct groove running along it, which is designed to hold and transfer sperm packets. Because this arm is so important for reproduction, males often keep it curled up protectively, which can be another visual cue for identification.
The Mating Process
The primary function of the hectocotylus is to transfer spermatophores, which are elongated packets of sperm, to the female. The male retrieves these packets from his own body cavity with the hectocotylus and then carefully inserts the tip of this specialized arm into the female’s mantle cavity, where her oviducts are located. The process can take hours as the spermatophore has a complex mechanism that secures it inside the female and releases the sperm.
This process is fraught with risk for the male, as females are often larger and can be cannibalistic, so males have developed various strategies. Some maintain a safe distance, stretching their hectocotylus over a considerable length to reach the female. In a more extreme adaptation, some species like the argonaut octopus have a detachable hectocotylus that separates from the male and delivers the sperm on its own. Conversely, species like the larger Pacific striped octopus engage in a more intimate, beak-to-beak mating, suggesting a lower risk of cannibalism.
Life After Mating
For the male octopus, mating marks the beginning of the end. Like the female, his life concludes after the reproductive phase in a process called senescence. This period of decline is triggered by hormones from the optic gland, which cause the octopus’s body to shut down. This hormonal change disrupts vital functions, including the digestive system, leading the octopus to stop eating.
They become uncoordinated, develop unhealing white lesions on their skin, and their skin may retract around the eyes. Without the drive to hunt or feed, the male weakens and eventually dies, sometimes over a period of weeks or months. While the female’s death is famously tied to the act of brooding her eggs, the male’s decline and eventual death are a direct, albeit slower, consequence of fulfilling his reproductive purpose.