Across the animal kingdom, reproduction is often portrayed as a triumph of survival, yet for some species, mating itself can be fatal. From insects to mammals, there are animals that knowingly, or instinctively, engage in reproductive behaviours that drastically shorten their lives or even lead to immediate death. These extreme strategies can seem puzzling, especially when viewed through a human lens that prioritises self-preservation.Such behaviours are not random acts of recklessness. In many cases, they are shaped by evolutionary pressures where the success of passing on genes outweighs the cost to the individual. For these animals, mating may be the single opportunity to reproduce, or the act itself may increase the chances that their offspring survive. Understanding these patterns requires looking beyond the outcome and examining the biological and behavioural drivers behind them.Animal behaviour research offers insight into how natural selection, competition, and reproductive urgency shape these high-risk mating strategies. 3 animals known to die during or immediately after matingDr Deepraj Prajapati, senior veterinarian at RD Pet Hospital, Ambedkar Nagar, tells indianexpress.com, “Three of the most well-documented examples are male antechinus, praying mantises, and certain species of octopus.”In male antechinus, a small Australian marsupial, mating is followed by a rapid physiological collapse, Dr Prajapati says. During the breeding season, males engage in prolonged mating sessions lasting several hours. This extreme effort causes a massive surge in stress hormones like cortisol, which suppresses the immune system, leads to internal bleeding, organ failure, and ultimately death within weeks of mating.“In praying mantises, males are sometimes cannibalised by females during or immediately after mating. While this behaviour is not universal, it occurs frequently enough to be evolutionarily significant. The male’s body provides a direct nutritional benefit to the female, improving egg development and survival,” states Dr Prajapati. Story continues below this adIn some octopus species, Dr Prajapati notes, particularly deep-sea octopuses, males die shortly after mating due to programmed biological decline. Females also undergo a form of reproductive death, where they stop feeding while guarding eggs until they die. This is driven by hormonal changes that prioritise reproduction over survival.How does evolution favour reproductive strategies that involve such extreme risks or guaranteed death?From an evolutionary standpoint, Dr Prajapati notes, survival only matters insofar as it enables reproduction. In species where individuals have a single or very short reproductive window, natural selection favours strategies that maximise reproductive output in that one opportunity, even if it results in death.These species often live in environments where future breeding chances are uncertain due to predation, climate instability, or short lifespans. “As a result, investing all available energy into reproduction becomes more advantageous than conserving energy for survival. Evolution does not select for longevity, but for genes that successfully pass to the next generation. In these cases, death after reproduction is not a failure of evolution but a highly specialised and efficient life-history strategy,” says the expert. Environmental or social factors that push particular species toward ‘mate-at-all-costs’ behavioursSeveral factors contribute to such extreme reproductive behaviours, including intense competition, skewed sex ratios, seasonal breeding constraints, and high juvenile mortality.Story continues below this adDr Prajapati explains, “In environments where mating opportunities are rare or limited to a short season, individuals that delay or conserve energy risk missing reproduction entirely. Social factors such as male competition or female choice can further intensify this pressure, pushing males to expend maximum effort in a single mating event.”These behaviours improve reproductive success by increasing mating duration, sperm transfer, or offspring viability. “Even though the individual dies, the genes benefit from higher chances of fertilisation and stronger offspring survival. In evolutionary terms, the success of the lineage outweighs the survival of the individual,” concludes Dr Prajapati.