Maxilla (arthropod mouthpart)
In arthropods, the maxillae (singular maxilla) are paired structures present on the head as mouthparts in members of the clade Mandibulata, used for tasting and manipulating food. Embryologically, the maxillae are derived from the 4th and 5th segment of the head and the maxillary palps; segmented appendages extending from the base of the maxilla represent the former leg of those respective segments. In most cases, two pairs of maxillae are present and in different arthropod groups the two pairs of maxillae have been variously modified. In crustaceans, the first pair are called maxillulae (singular maxillula).
Modified coxae at the base of the pedipalps in spiders are also called "maxillae",[1] although they are not homologous with mandibulate maxillae.
Myriapoda
Millipedes
In
Centipedes
In
Crustaceans
In crustaceans, the two pairs of maxillae are called maxillulae (1st pair) and maxillae (2nd pair). They serve to transport food to the mandibles but also frequently help in the filtration process and additionally they may sometimes play a role in cleaning and grooming. These structures show an incredible diversity throughout crustaceans but generally are very much flattened and leaf-like. The two pairs are normally positioned very close together and their apical parts generally are in direct contact with the mandible.[5]
Hexapoda
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 the maxillary palp. The lacinia is often strongly sclerotized and toothed. It functions to cut and manipulate food in the mouth.[6] The galea is a broad, scoop-like, lobe structure, which assists the maxillary palps in sampling items before ingestion. The maxillary palp is serially homologous to the walking leg while the cardo and stipes are regarded by most to be serially homologous to the first leg segment, the coxa.[7] The
Specializations
In many hexapods, the
References
- ISBN 978-0-19-973482-5.
- ^ Hopkin, S. P. and Read, H. J. 1992. The Biology of Millipedes. Oxford University Press.
- ^ Camatini, M. 1979. Myriapod Biology. Academis Press Inc.
- ^ Lewis, J. G. E. 1981. The Biology of Centipedes. Cambridge University Press.
- ^ Forest, J and von Vaupel Klein J. C. 2004. The Crustacea. Brill Academic Publishers. Volume 1.
- ^ a b Gullan, P. J. and Cranston, P. S. 2005. The Insects: An Outline of Entomology. 4th edition. Blackwell Publishing
- PMID 10861829.