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Free-living worm species do not live on land but instead live in marine or freshwater environments or underground by burrowing. In biology, "worm" refers to an obsolete taxon, Vermes, used by Carolus Linnaeus and Jean-Baptiste Lamarck for all non-arthropod invertebrate animals, now seen to be paraphyletic. The name stems from the Old English ...
Arthropoda is the largest animal phylum with the estimates of the number of arthropod species varying from 1,170,000 to 5~10 million and accounting for over 80 percent of all known living animal species. [35] [36] One arthropod sub-group, the insects, includes more described species than any other taxonomic class. [37] The total number of ...
Arthropods are intermediate hosts of Hymenolepis nana, otherwise known as the "dwarf tapeworm," while humans are used as final hosts. Humans become infected and develop hymenolepiasis through eating infected arthropods, ingesting eggs in water inhabited by arthropods, or from dirty hands. This is a common and widespread intestinal worm. [5]
From a total of around 7,000 species, only about 150 species are widely distributed around the world. These are the peregrine or cosmopolitan earthworms. [ 49 ] Of the 182 taxa of earthworms found in the United States and Canada, 60 (33%) are introduced species.
Researchers have uncovered fossils of giant predator worms, some of Earth’s earliest carnivorous animals that roamed the seas 518 million years ago.
More than 99 percent of all species, amounting to over five billion species, [7] that ever lived on Earth are estimated to be extinct. [8] [9] Estimates on the number of Earth's current species range from 10 million to 14 million, [10] of which about 1.2 million have been documented and over 86 percent have not yet been described. [11]
The larva, named Youti yuanshi, dates back to 520 million years ago, around a time that a large diversity of life began to emerge on Earth, including many major animal groups alive today.
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