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An antenna is considered segmented if each of the annuli is separate from those around it and has individual muscle attachments. Flagellate antennae, on the other hand, have muscle attachments only around the base, acting as a hinge for the flagellum—a flexible string of annuli with no muscle attachment. [5]
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 ...
Diagram of a single maxilla from the cockroach Periplaneta americana showing the anatomy and musculature The generalized condition in hexapods is for the first pair of maxillae to consist of a basal triangular sclerite called the cardo and a large central sclerite called the stipes from which arise three processes: the lacinia, the galea and ...
Tömösváry organ (arrow) on the head of a symphylan, just behind the base of an antenna. Tömösváry organs, also known as temporal organs or postantennal organs [1] are specialized paired sensory organs found in certain groups of myriapods (e.g. centipedes and millipedes) and hexapods (e.g. springtails), located on the head near the base of the antennae.
Two sets of muscles move the mandibles in the coronal plane of the mouth: abductor muscles move insects' mandibles apart ; adductor muscles bring them together . They do this mainly in opening and closing their jaws in feeding, but also in using the mandibles as tools, or possibly in fighting.
Springtails (class Collembola) form the largest of the three lineages of modern hexapods that are no longer considered insects.Although the three lineages are sometimes grouped together in a class called Entognatha because they have internal mouthparts, they do not appear to be any more closely related to one another than they are to all insects, which have external mouthparts.
Note the antenna-bearing somite 1 was thought to be lost in Chelicerata. Formation of anterior segments across arthropod taxa based on gene expression and neuroanatomical observations, [ 10 ] [ 11 ] Note the chelicera(Ch) and chelifore(Chf) arose from somite 1 and thus correspond to the first antenna(An/An1) of other arthropods.
In a 2012 molecular study, von Reumont et al. challenge the monophyly of Vericrustacea: they present four versions of Pancrustacea cladogram (figures 1–4), and in all four figures Remipedia is a sister group to Hexapoda, and Branchiopoda is a sister group to (Remipedia + Hexapoda). Thus, their data strongly suggest that Branchiopoda is more ...