Considered the largest phylum in the Animal Kingdom, phylum Arthropoda contains many forms and variations of species. However, the common features that define an Anthropod from any other phylum before it are:
- several jointed appendages - exoskeleton - outer shell/skin composed of protein and chitin - segmented body plan - compound eyes - thousand-lensed eyes detecting color & motion - brains and well-developed nervous systems strung by ganglia * molting - method of growth by shedding layers * mandibles - grasping appendages around the mouth |
- most terrestrial arthropods transfer gases through a network of branching tracheal tubes throughout the body with small openings in the exoskeleton called spiracles
- terrestrial arthropods use malpigian tubules, sac-like organs, to extract waste from blood to combine it into a paste with the digestive waste - open circulatory systems |
Subphylums of Arthropoda
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Subphylum Chelicerata (Spiders, Scorpions, Horseshoe Crabs)
Species in subphylum Chelicerata feature:
In contrast to most arthropods, Chelicerata do not feature:
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Subphylum Myriapoda (Centipedes, Millipedes)
The subphylum Myriapoda is most recognized by the class within it, Uniramia, which includes centipedes and millipedes.
Class Chilopoda: centipedes
Class Diplopoda: millipedes
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Subphylum Trilobitomorpha (Trilobites)
Trilobites that composed the subphylum Trilobitomorpha existed 520 million years ago and have all since been extinct. The name trilobite means "three-lobed," referring to the central axial lobe and the pleural lobes on each side of the body.
Trilobites feature:
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http://animaldiversity.ummz.umich.edu/
http://www.trilobites.info/
http://www.trilobites.info/