Naturalist Notes: The Cradle of Maui Nui

Originally formed by an underwater volcanic vent, or “hotspot”, the Hawaiian Islands began with fire and water. Through surging molten hot magma, shifting ocean plates, and many, many  years, a series of islands were formed. The original islands were quite different from those we know as Hawaii today. The islands now called Maui, Lana’i, Moloka’i, and Kaho’olawe were once linked together by a wide saddle of land, and together formed a prehistoric island called Maui Nui. In the Hawaiian language, Nui means “great”, or “large”.  As glaciers melted, sea levels rose, and the island settled and eroded,  the basin between these islands filled with water.

Today, this basin is a shallow, warm haven in the middle of the Pacific Ocean. It is on average only 500 metres deep, compared to the surrounding abyssal ocean floor (3000-6000 m). It is for this reason that nearly two-thirds of the humpback population have chosen the Hawaiian islands as their winter home. The mild waters are an ideal location to give birth to their calves, who lack the thick insulating blubber that allows the humpbacks to survive cold Northern waters. Although this area lacks the small fish and krill that humpbacks need to feed on, the young whales can gain strength from their mothers’ rich milk. All the while, the shallow basin is the perfect nursery for calves to grow, play, and gain strength before making their spring journey North. Once they succeed in this epic journey (as much as 8,000 km one way), the famished adults can fill their bellies, as well as teach their young how lunge feeding is done!

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