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Worms vary in size from microscopic to over 1 metre (3.3 ft) in length for marine polychaete worms (bristle worms); [1] 6.7 metres (22 ft) for the African giant earthworm, Microchaetus rappi; [2] and 58 metres (190 ft) for the marine nemertean worm (bootlace worm), Lineus longissimus. [3]
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]
It is a paraphyletic grouping including all animals excluding the chordate subphylum Vertebrata, i.e. vertebrates. Well-known phyla of invertebrates include arthropods, mollusks, annelids, echinoderms, flatworms, cnidarians, and sponges. The majority of animal species are invertebrates; one estimate puts the figure at 97%. [1]
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 ...
Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (helminths) are the cause of soil-transmitted helminthiases. They are classified along with arthropods, tardigrades and other moulting animals in the clade Ecdysozoa.
The team said this ancient creature “provides key clues” on how modern arthropods – a group of animals that includes insects, spiders, crabs and centipedes – evolved from worm-like ancestors.
Earthworm head. Depending on the species, an adult earthworm can be from 10 mm (0.39 in) long and 1 mm (0.039 in) wide to 3 m (9.8 ft) long and over 25 mm (0.98 in) wide, but the typical Lumbricus terrestris grows to about 360 mm (14 in) long. [9]
The larvae infest arthropods, ... group of genes — about 200 in all — was absent from both horsehair worm species, suggesting that this was a genomic quirk in the group rather than a data ...