Wildlife
Semelparous organisms reproduce only once in their lives and then die. The most well known ones are Pacific salmon that perish after spawning. Other examples are squid, mayflies and plants which die after setting seed (annuals). The adult diverts resources into producing huge amounts of offspring to ensure sufficient numbers reach maturity without any parental care. This is why bears largely ignore dead salmon after they've spawned - all the salmon's fat has gone into producing sperm and eggs and little nutrional value is left.
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Do and die
As soon as they have fulfilled their reproductive duties, brook lampreys die.
As soon as they have fulfilled their reproductive duties, brook lampreys die.
Desert bloom
When the rains come, the southern African desert blazes with colour for a few short weeks.
When the rains come, the southern African desert blazes with colour for a few short weeks.
Final destination
Exhausted sockeye salmon go the extra mile to reach their spawning grounds.
Exhausted sockeye salmon go the extra mile to reach their spawning grounds.
17 year swarm
Periodical cicadas emerge from the ground in their thousands.
'A beautifully filmed sequence of one of nature's greatest spectacles. David Attenborough summons an amorous, but misguided, male cicada with a snap of his fingers. A mass cicada emergence like this is something I would love to witness.' (George McGavin: scientific advisor on Life in the Undergrowth)
Brief encounters
Giant mayflies have only half an hour's flying time to find a mate.
The lifespan of an adult mayfly can vary from just 30 minutes to one day depending on the species, making them the proud owners of shortest adult lifespan of any insect. In this memorable sequence the transient beauty of some natural history events is clearly illustrated. To film them you have to make sure you are in the right place at exactly the right time, which takes not just careful planning, but good luck. With the male mayflies energy reserves allowing for only half an hour's flying time, the window of opportunity for capturing this event is stressfully short for both crew and creature!
Semelparity and iteroparity refer to the reproductive strategy of an organism. A species is considered semelparous if it is characterized by a single reproductive episode before death, and iteroparous if it is characterized by multiple reproductive cycles over the course of its lifetime. Some plant scientists use the parallel terms monocarpy and polycarpy. See also Plietesials.
In truly semelparous species, death after reproduction is part of an overall strategy that includes putting all available resources into maximizing reproduction, at the expense of future life (see "Trade-offs", below). In any iteroparous population there will be some individuals who die between their first and second reproductive episodes, but unless this is part of a syndrome of programmed death after reproduction, this would not be called semelparity.
This distinction is also related to the difference between annual and perennial plants. An annual is a plant that completes its life cycle in a single season, and is usually semelparous. Perennials live for more than one season and are usually (but not always) iteroparous.
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Other Reproductive strategy behaviours
Take a trip through the natural world with our themed collections of video clips from the natural history archive.
Nature's record breakers
Animal kingdom record breakers - how fast can a cheetah run, how heavy is an elephant and what's bigger than a dinosaur? Watch amazing video clips from the BBC archive and uncover the fascinating facts about our smallest primate, the longest stick insect and the most venomous snake.
George's marvellous minibeasts
A video collection featuring bugs and insects in amazing close up selected by insect expert and TV presenter George McGavin, with Goliath spiders, killer centipedes, ants and moths.
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Bamboo 
Labord's chameleon
Brown trout
Salmon family
Sockeye salmon
Brook lamprey
Common cuttlefish
Giant cuttlefish
North Pacific giant octopus
Common glow-worm
Monarch butterfly
Swallowtail
Mayflies
Tisza mayfly