The tide line where land and sea meet possesses an ancestral pull for many species. Some still answer it, arriving to provide dedication to breeding – but many at their peril.

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In order to ensure that genetic inheritance is passed on to future populations and place guarantee on the survival of species , the most profound, bizarre, motivating and in this case dangerous breeding methods and tactics have evolved across centuries of struggles, competition and dangers. So let’s take a look at those species which have become locked in the time of breeding at shore lines.

Prisoners of a past before dinosaurs: The Horseshoe Crab

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The Horseshoe crab is an ancient master of the water, which scuttles and runs in the waters with ten eyes and blood that protects itself from infection. And just like it sounds, these crabs are not really crabs at all but distant relatives of scorpions and spiders. Their smooth shell and long tail wraps them up in an oddly alien air, but in fact these are among the oldest inhabitants on earth and have changed very little since the Paleozoic Era 540 million years ago.

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In early summer these alien related horseshoe crabs drag themselves from the sea with scuttling legs to lay their eggs along the sandy beaches of the eastern United States much like their ancestors did before the arrival of dinosaurs.  When the female lays a whooping 80,000 eggs, she scrapes and builds a shallow nest in order to accommodate the large numbers. During this manic preparation the male clings himself to the female’s forelegs preparing fertilisation for as soon as eggs are delivered.

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This is a cruel, hard process of fertilisation as during this time a great confliction takes off between horseshoe crabs and the many birds making their annual migrations from South American to their Arctic breeding grounds. Despite being well protected from their hardened, course shells; their greenish eyes are the perfect fancy of many birds.  Sitting next to thousands of nutritious packed eggs and a large array of hungry mouths waiting to seize and steal them, the horseshoe crab faces a great loss of both eyes and offspring that they have worked so hard to develop. To some extent it seems that horseshoe crabs have become prisoners of a pattern developed but not lost in the past.

Eight week navigational noble act by Green Turtles:


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Green turtles are a favourable marine creature that has been adored for its dedicated migrations and tear-drop shaped carapace and is another aquatic warrior of facing death in order to reproduce. Every two to three years (in November) numbers of green turtles strike out if their homes near the Brazilian coats to begin epic journeys of an encountered 1250 miles. But where are they heading? Their goal – a land fragment of only 34sq miles: Ascension Island, South Atlantic. After reaching their ancestral breeding grounds around eight weeks after leaving, under the cover of darkness, the females drag themselves up onto the islands beaches.

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Here, each female extensively digs a hole in the sand and plants around 140 eggs. The process is not easy, resulting in up to several attempts. These turtles were not built for movement on land and lose all their energy dragging themselves across the sands. Weighed down by an inflexible shell, the female finds it difficult to even breathe.  Over time, the slow dance of the continental’s drifts has compounded the ever-lengthening time and distance of their journeys as South America continues to steadily move farther away from the turtle’s breeding grounds.  Even after battling against such a far-reaching journey and unbeatable effort of laying eggs, the chance of life is instantly stolen away for some due to their economic value, as poachers and hunters kill and remove both the mothers and eggs from the island.

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Fish that risk death to mate on the Californian Beaches:


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When the moon is full and glows its light across the beaches of California, every march these beaches are silvered by the slender shiny bodies of grunion in swarms of millions. These small fish stretch themselves as ribbons along the waters edge as far as the eye can see, and within each crafted break of the waves over the sand delivers a fresh silver cargo to lie writhing on the shore.

By violently thrashing their tails, the females swiftly wriggle themselves into the sands becoming wedged upright, leaving only their sleek heads sticking out. Each male selects a preferred female for breeding and once chosen bends himself around her to deposit his sperm/milt as she lays her eggs. If the pair of successful grunion gets their timing right, with a combination of laying eggs at exactly the right spot, the fertilised eggs remain undisturbed in the damp sands over the next two weeks. This is an indispensable form of protection from sea predators until the gravitational pull of the moon and sun rise the highest tide of the month.

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The incredible transition of the eggs hatching is remarkably triggered by the vibrations shot from the thundering waves across the sands of the spawning ground.  This whole process is a very dangerous breeding application to play – high chances of being left stranded on the dinner plate (sand) for gulls and the death of suffocation. A fate that also awaits many of the eggs hatchings leaves large populations of grunions lives taken or consumed via the dedication of reproduction.

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So whether it is facing the weight of shells, suffocation, consumption or theft of their economic value we can see that playing the game of reproduction across shorelines is a very treacherous method. Nevertheless, through sheer dedication and incentive these marine populations have remained untouched, despite some giving up their own lives. It is these species that deserve protection of genetic material and status for future populations for being such committed parents.

  • JP Oldham

    Amazing article, author writes beautifully and captures the readers interest while raising awareness of these incredible organisms. Its also nice to read about animals other than the typical flagship species. Keep it up, cannot wait to read more oh and also some incredible images to accompany.

  • Name

    thanks for using my pic and providing due credit.

    http://www.flickr.com/photos/the_world_as_i_see/