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Species of the infraorder Cetacea A phylogenetic tree showing the relationships among cetacean families. [1]The evolution of cetaceans is thought to have begun in the Indian subcontinent from even-toed ungulates (Artiodactyla) 50 million years ago (mya) and to have proceeded over a period of at least 15 million years. [2]
A food web model is a network of food chains. Each food chain starts with a primary producer or autotroph, an organism, such as an alga or a plant, which is able to manufacture its own food. Next in the chain is an organism that feeds on the primary producer, and the chain continues in this way as a string of successive predators.
Heavy metals such as mercury accumulate up the food chain. Cetaceans, generally at the top of the food chain, are the principal animals affected. [72] The mercury is a by-product of gold washing in the Amazon basin. [72] Mercury and selenium have been detected in several cetacean species hunted off Saint Vincent for food. [147]
Whales defecate at the ocean's surface; their excrement is important for fisheries because it is rich in iron and nitrogen. The whale feces are liquid and instead of sinking, they stay at the surface where phytoplankton feed off it. [90] [91] Upon death, whale carcasses fall to the deep ocean and provide a substantial habitat for marine life.
The release of iron from whale feces encourages the growth of phytoplankton in the sea, [5] which not only benefits the marine food chain, but also sequesters carbon for long periods of time. [5] When phytoplankton, which is not consumed in its lifetime, perishes, it descends through the euphotic zone and settles down into the depths of sea.
Altogether the ocean occupies 71 percent of the world surface, [4] averaging nearly 3.7 kilometres (2.3 mi) in depth. [27] By volume, the ocean provides about 90 percent of the living space on the planet. [4] The science fiction writer Arthur C. Clarke has pointed out it would be more appropriate to refer to planet Earth as planet Ocean. [28] [29]
Also known as the takuache, and the cuh, the Edgar can make those who embrace it look like fools or misfits. Moe Howard , the leader of the Three Stooges, wore one. So did Lloyd Christmas ...
A researcher fires a biopsy dart at an orca.The dart will remove a small piece of the whale's skin and bounce harmlessly off the animal. Cetology (from Greek κῆτος, kētos, "whale"; and -λογία, -logia) or whalelore (also known as whaleology) is the branch of marine mammal science that studies the approximately eighty species of whales, dolphins, and porpoises in the scientific ...