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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 ...
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]
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 ...
Consequently, estimates of the number of nematode species are uncertain. A 2013 survey of animal biodiversity suggested there are over 25,000. [4] [5] Estimates of the total number of extant species are subject to even greater variation. A widely referenced 1993 article estimated there might be over a million species of nematode. [6]
Mermithidae is a family of nematode worms that are endoparasites in arthropods. As early as 1877, Mermithidae was listed as one of nine subdivisions of the Nematoidea. [2] Mermithidae are confused with the horsehair worms of the phylum Nematomorpha that have a similar life history and appearance. Mermithids are parasites, mainly of arthropods ...
The Bobbit worm (Eunice aphroditois) is a predatory species that can achieve a length of 3 m (10 ft)), with an average diameter of 25 mm (1 in). Dimorphilus gyrociliatus has the smallest known genome of any annelid. The species shows extreme sexual dimorphism. Females measure ~1 mm long and have simplified bodies containing six segments, a ...
Some species have wings. They are an extremely diverse group, with up to 10 million species. Arthropods are invertebrate animals with a chitinous exoskeleton, segmented bodies, and jointed legs. The phylum Arthropoda contains numerous taxonomic orders in over 20 classes.
This trend is concerning many scientists, as marine worms act as an important food source for many fish and wading birds. Marine worms are often keystone species in an ecosystem, and the introduction of plastic in the oceans not only diminishes the growth rates of the marine worms, but also affects the food chain of that ecosystem. [10]