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The coast, the frontier, between land and sea. This is the most dynamic of all the ocean habitats. The challenge here is to survive change,extreme change.Cape Douglas, on the mostwesterly of the Galapagos islands, totally unprotected from the massive rollers of the Pacific ocean and one of the roughest coast lands in the world. The marinely iguanas of theGalapagos are the world’s only sea-going lizards. Seaweed is all they eat, but doing so is a dangerous business. The local crabs have become specially flattened, minimising the effective of the ponding waves,and the iguanas have huge claws to grip the rocks. This seaweed really is fast food. There are only a few second in which to to grab a few monthfuls before the next breaker comes ponding in. Female iguanas feed only on the exposed rocks. But the males,which are larger swim and dive beneath the surface to reach the weed. They go as deep as ten metres,for there beyond the destructive reachof the waves, they find the best fronds. Being cold-blooded, theyhave to return to landafter about ten minutes orso to warm up again in the sun. Finding food is not the onlychallenge for coastal residents. These rocky shores are hardlya safe place to lay their eggs, and each year the marine iguanashave to journey inlandto find a more suitable one. The females lay their eggs in burrowsand leave them there to hatch,and to do that theyneed nice soft sand. Down at the water edge, it was easyto escape danger in rocky crevices,but up here the femalesare dangerously exposed. A Galapagos hawk. The lizards don't give upwithout a struggle. These hawks stay on the coast all yearBut they are exceptional. The majority of the birdsthat frequent this frontierspend most of their time elsewherein or above the open ocean. However all seabirds have to cometo land in order to lay their eggs. And after spending many lonelymonths searching the ocean for food,they have tore-establishtheir social relationships. Frigate birds display andexchange nesting material. Waved albatross dance. The need to lay their egg on firm groundties the albatross to the coastbut parental responsibilitiesare shared. While one looks after the egg,the other can go off to feed. Theneed to breed bringsmany different animalsto the coast each yearfor a few weeks. Male sea turtles spend alltheir lives at sea, but the females,like birds, must come toland to lay their eggs. To do that green turtles that liveand feed off the coast of Brazilswim fifteen hundred miles to thetiny island of Ascensionthat lies bang in the middleof the Atlantic Ocean. Exactly how they manage tonavigate with such accuracyand find this tiny lump of rock,just seven miles wide is a mystery. But each year up to five thousandturtles manage to do so and then,close to the coast of Ascension,they mate. Travelling to and from Ascension andnesting here can take up to six monthsand throughout that entire time,none of them feed at all. After mating a female has toleave her natural elementand haul herself up onto land. She does so at night,laying about three or four timesat around fifteen day intervals. After that she then swims all the wayback to the seas off Brazil. She returns to this very sameisland throughout her life. Remarkably, all the world's sea turtlesreturn year after yearto just a few traditionalbreeding sites. Crab lsland, in Australia,is one of them. This tiny two-mile long crescent of sand,lying a few miles off. Queensland's northerly tip,provides nesting sitesfor half the entire populationrarest sea turtles. Flat-backed turtles are large,over a metre longbut they have to be careful. There are other giantreptiles here too. Salt-water crocodiles. Every night throughout the yearthere are flat-backs burying their eggsall along this lonely stretch of sand. Nine weeks later and thingsare about to happen. These eyes shining in the darknessbelong to night herons. As if from nowhere, hundreds of birdssuddenly appear on the sand dunes. Pelicans wait patiently. Jabiru storks pace up and downBefore long they see whatthey've been waiting for.Because these turtles laytheir eggs throughout the year,the hatchlings emerge night after nightin a steady trickle of beak sized