Arthropods are invertebrate animals having an exoskeleton , a segmented body, and paired jointed appendages . Arthropods form the phylum Arthropoda . They are distinguished by their jointed limbs and cuticle made of chitin , often mineralised with calcium carbonate . The arthropod body plan consists of segments, each with a pair of appendages. Arthropods are bilaterally symmetrical and their body possesses an external skeleton . In order to keep growing, they must go through stages of moulting , a process by which they shed their exoskeleton to reveal a new one. Some species have wings. They are an extremely diverse group, with up to 10 million species.
Wolf spider carrying its young in its egg sac.
Marrella , one of the puzzling arthropods from the Burgess Shale
A shed carapace of a lady crab , part of the hard exoskeleton
Arthropods are invertebrate animals with a chitinous exoskeleton, segmented bodies, and jointed legs. The phylum Arthropoda contains numerous taxonomic orders in over 20 classes.
Class Insecta (Insects)
Head of a wasp with three ocelli (centre), and compound eyes at the left and right
A pair of Simosyrphus grandicornis hoverflies mating in flight.
Aedes aegypti , a parasite, is the vector of dengue fever and yellow fever
Order †Carbotriplurida
Infraclass Thysanura
Infraclass Pterygota
Order †Reculida
Order †Perielytrodea
Order †Eoblattida
Clade Panephemeroptera
Clade Odonataptera
Clade Palaeodictyopteroidea
Clade Polyneoptera
Order †Paoliida
Order †Protorthoptera (Paraphyletic assemblage of basal and stem polyneopterans)
Order †Sheimiodea
Order Zoraptera – 28 (Angel insects)
Order †Archelytroidea
Order †Protelytroptera
Order Dermaptera – 1,816 (Earwigs)
Order Plecoptera – 2,274 (Stoneflies)
Order †Caloblattinidea
Order †Alienoptera
Order Mantodea – 2,200 (Mantises)
Order Blattodea – 3,684–4,000 (Cockroaches and termites )
Order Grylloblattodea – 34 (ice-crawlers)
Order Mantophasmatodea – 15 (gladiators)
Order Phasmatodea – 2,500–3,300 (Stick insects or stick-bugs)
Order Embioptera – 200–300 (Webspinners)
Order †Chresmododea
Order †Cnemidolestida
Order †Titanoptera
Order †Caloneurodea
Order Orthoptera – 24,380 (Grasshoppers , locusts , crickets , etc.)
Clade Clareocercaria
Clade Holometabola
Order Hymenoptera – 115,000 (Sawflies , wasps , bees , and ants )
Order Strepsiptera – 596 (Twisted-wing parasites)
Order Coleoptera – 360,000–400,000 (Beetles)
Order †Glosselytrodea
Order Raphidioptera – 210 (Snakeflies)
Order Megaloptera – 250–300 (Alderflies , dobsonflies , and fishflies )
Order Neuroptera – 5,000 (Net-winged insects)
Order †Protomecoptera
Order †Tarachoptera
Order †Permotrichoptera
Order Lepidoptera – 174,250 (Butterflies and moths )
Order Trichoptera – 12,627 (Caddisfly)
Order †Paratrichoptera
Order †Protodiptera (Permotipula and Permila )
Order Diptera – 152,956 (Flies)
Order †Paramecoptera
Order Nannomecoptera
Order Mecoptera – 481 (Scorpionflies)
Order Neomecoptera
Order Siphonaptera – 2,525 (Fleas)
Class Pycnogonida
Pycnogonida
A representative millipede and centipede (not necessarily to scale)
Ammodesmus nimba from Guinea, West Africa, curled in a defensive coil
A pauropod
Order †Agnostina
Order †Henningsmoenicarida
Order †Cambropachycopida
Order †Cambrocarida
Order †Martinssoniida
Order †Phosphatocopida
Order †Bostrichopodida
Branchiopods
Class Ostracoda (Ostracods, or seed shrimp)
Ostracod
Subclass †Leperditicopa
Order †Leperditicopida
Order thippslicus
Class Malacostraca (Malcostracans, such as crabs and lobsters)
Syncarid Atlantic blue crab Callinectes sapidus
Hoplocarid
Nebalia bipes Phyllocarid
Order ?†Discinocarida
Order †Archaeostraca
Order †Hoplostraca
Order Leptostraca
Paradoxides
Order †Sinoburiida
Order †Xandarellida
Reconstructed Leanchoilia