Birth to Senescence in Three Years
While their gastropod and bivalve relatives can live for more than fifty years, octopuses have relatively short life spans. The Giant Pacific octopus lives for about three years, while smaller octopuses may live for only 80 days, Typically the octopuses that live in colder water have longer life spans. Almost all species of octopus are semelparous, which means they die shortly after reproducing. Following reproduction, there is a senescent stage that leads to death (Anderson et al 2002).
Little is known about the mating and courtship rituals of octopus due to their solitary nature, however in 2008 researchers at UC Berkeley released a study where they followed a species of octopus, the Octopus Abdopus aculeatus, and detailed some of the first courtship behavior observations. The species of octopus is not unique, therefore the researchers believe more octopus species behave in similar manners. The researchers observed mate-guarding behavior, fighting off rival males and displaying striped body patterns. In addition, researchers witnessed males who would mimic female coloration and behavior to mate with a guarded female (Anwar 2008).
Reproduction occurs through internal fertilization when males insert their hectocotylus into the mantle cavity of the female. The ligula inserts the spermatophore into an oviduct and can also remove rival mates’ spermatophores as females can store more than one spermatophore (Anderson et al 2003; Quintero et al 2011).
Observations suggest females select older mates which may mean the male has adaptations that have allowed it to survive. Voight (1991) found that ligula morphology was a species-specific characterisitic and hypothesized it reduced interspecific mating. Voight (1991) also observed that ligula length reached its maximum length when the male was sexually mature and also hypothesized ligula length is a signal to females of male maturity.
After mating, the female returns to her den and lays eggs; the number of eggs laid is proportional to the size of the octopus species and can range between 100,000 and 500,000 (Quinteiro et al 2011). The male may mate with several females, but typically a month after the male first mates, the male dies while the female begins her senescent stage after laying her eggs (Anderson et al 2002).
Senescence, though bizarre to the outsider, is a standard part of an octopuses’ life cycles and male and female octopus experience senescence in unique ways.
Male Senescence:
A male octopus will experience senescence after maturity and shortly after reproduction. Males have fewer visible symptoms of senescence but cessation of feeding is the primary symptom. As they stop eating, males are known to loose up to 32% of their body weight. In addition, males are observed to engage in undirected and uncoordinated activity. They appear as if they forget how to swim and control their arms. During these times, males make themselves more available to predators. Lesions also appear over the skin and increase in size and number before death (Anderson et al 2002)
Female Senescence:
A female will hold onto life until her eggs have been hatched, but just barely. After lying eggs, a female will not leave her den and thus will not eat but instead begin to metabolize her own muscle to provide just enough energy to care for the eggs. Females typically loose 50 to 70% of their body eggs while in their senescent stage. This energy allows the female to aerate her eggs and protect them from predators. The skin around their eyes will retract and appear limp as their coloration typically appears to be a grayish-white. As soon as the eggs under a female’s care have hatched, the female will die, leaving the newly hatched octopuses to survive on their own (Anderson et al 2002). This hatching and senescence process was caught on film in 2009 by amateur diver in Puget Sound (see link below).
Little is known about the mating and courtship rituals of octopus due to their solitary nature, however in 2008 researchers at UC Berkeley released a study where they followed a species of octopus, the Octopus Abdopus aculeatus, and detailed some of the first courtship behavior observations. The species of octopus is not unique, therefore the researchers believe more octopus species behave in similar manners. The researchers observed mate-guarding behavior, fighting off rival males and displaying striped body patterns. In addition, researchers witnessed males who would mimic female coloration and behavior to mate with a guarded female (Anwar 2008).
Reproduction occurs through internal fertilization when males insert their hectocotylus into the mantle cavity of the female. The ligula inserts the spermatophore into an oviduct and can also remove rival mates’ spermatophores as females can store more than one spermatophore (Anderson et al 2003; Quintero et al 2011).
Observations suggest females select older mates which may mean the male has adaptations that have allowed it to survive. Voight (1991) found that ligula morphology was a species-specific characterisitic and hypothesized it reduced interspecific mating. Voight (1991) also observed that ligula length reached its maximum length when the male was sexually mature and also hypothesized ligula length is a signal to females of male maturity.
After mating, the female returns to her den and lays eggs; the number of eggs laid is proportional to the size of the octopus species and can range between 100,000 and 500,000 (Quinteiro et al 2011). The male may mate with several females, but typically a month after the male first mates, the male dies while the female begins her senescent stage after laying her eggs (Anderson et al 2002).
Senescence, though bizarre to the outsider, is a standard part of an octopuses’ life cycles and male and female octopus experience senescence in unique ways.
Male Senescence:
A male octopus will experience senescence after maturity and shortly after reproduction. Males have fewer visible symptoms of senescence but cessation of feeding is the primary symptom. As they stop eating, males are known to loose up to 32% of their body weight. In addition, males are observed to engage in undirected and uncoordinated activity. They appear as if they forget how to swim and control their arms. During these times, males make themselves more available to predators. Lesions also appear over the skin and increase in size and number before death (Anderson et al 2002)
Female Senescence:
A female will hold onto life until her eggs have been hatched, but just barely. After lying eggs, a female will not leave her den and thus will not eat but instead begin to metabolize her own muscle to provide just enough energy to care for the eggs. Females typically loose 50 to 70% of their body eggs while in their senescent stage. This energy allows the female to aerate her eggs and protect them from predators. The skin around their eyes will retract and appear limp as their coloration typically appears to be a grayish-white. As soon as the eggs under a female’s care have hatched, the female will die, leaving the newly hatched octopuses to survive on their own (Anderson et al 2002). This hatching and senescence process was caught on film in 2009 by amateur diver in Puget Sound (see link below).