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Arthropod eyes Head of a wasp with three ocelli (center), and compound eyes at the left and right. Most arthropods have sophisticated visual systems that include one or more usually both of compound eyes and pigment-cup ocelli ("little eyes"). In most cases, ocelli are only capable of detecting the direction from which light is coming, using ...
The Arthropoda, Onychophora, and Tardigrada have been grouped together as the Panarthropoda because they are distinguished by segmented body plans. [20] Dunn et al. in 2008 suggested that the tardigrada could be grouped along with the nematodes, leaving Onychophora as the sister group to the arthropods. [ 11 ]
The subphylum Hexapoda (from Greek for 'six legs') or hexapods comprises the largest clade of arthropods and includes most of the extant arthropod species. It includes the crown group class Insecta (true insects), as well as the much smaller clade Entognatha, which includes three classes of wingless arthropods that were once considered insects: Collembola (springtails), Protura (coneheads) and ...
As members of Myriapoda, centipedes like this Scolopendra polymorpha are part of phylum Uniramia. Uniramia (uni – one, ramus – branch, i.e. single-branches) is a group within the arthropods. In the past this group included the Onychophora, which are now considered a separate category. The group is currently used in a narrower sense. [2]
Arthropods (/ ˈ ɑːr θ r ə p ɒ d / ARTH-rə-pod) are invertebrates in the phylum Arthropoda. They possess an exoskeleton with a cuticle made of chitin , often mineralised with calcium carbonate , a body with differentiated ( metameric ) segments , and paired jointed appendages .
There has been much debate as to which arthropod group is most closely related to the Myriapoda. [20] Under the Mandibulata hypothesis, Myriapoda is the sister taxon to Pancrustacea , a group comprising the Crustacea and Hexapoda (insects and their close relatives).
The subphylum Chelicerata (from Neo-Latin, from French chélicère, from Ancient Greek χηλή (khēlḗ) 'claw, chela' and κέρας (kéras) 'horn') [1] constitutes one of the major subdivisions of the phylum Arthropoda.
The term phylum was coined in 1866 by Ernst Haeckel from the Greek phylon (φῦλον, "race, stock"), related to phyle (φυλή, "tribe, clan"). [4] [5] Haeckel noted that species constantly evolved into new species that seemed to retain few consistent features among themselves and therefore few features that distinguished them as a group ("a self-contained unity"): "perhaps such a real and ...