is an invertebrate animal having an exoskeleton
(external skeleton), a segmented body, and jointed appendages.
Arthropods are members of the phylum Arthropoda (from Greek ἄρθρον
árthron, "joint", and ποδός podós "foot", which together mean "jointed
feet"), and include the insects, arachnids, crustaceans, and others.
Arthropods are characterized by their jointed limbs and cuticles, which
are mainly made of α-chitin; the cuticles of crustaceans are also
biomineralized with calcium carbonate. The rigid cuticle inhibits
growth, so arthropods replace it periodically by molting. The arthropod
body plan consists of repeated segments, each with a pair of
appendages. They have over a million described species, making up more
described living animal species. Source:
The subphylum Myriapoda
centipedes, and their
relatives and have many
body segments, each bearing one or two pairs of legs.
They aresometimes grouped with the hexapods. Source:
For an article on Myriapoda go to Polydesmid
millipedes at Protea Hill Farm,
Hexapoda comprise insects and three small orders of insect-like animals
with six thoracic legs. They are sometimes grouped with the myriapods,
in a group called Uniramia, though genetic evidence tends to support a
closer relationship between hexapods and crustaceans.
The subphylum Hexapoda (from the Greek for six legs) constitutes the
largest (in terms of number of species) grouping of arthropods and
includes the insects as well as three much smaller groups of wingless
arthropods: Collembola, Protura, and Diplura (all of these were once
considered insects). The Collembola (or springtails) are very abundant
in terrestrial environments. Hexapods are named for their most
distinctive feature: a consolidated thorax with three pairs of legs.
Most other arthropods have more than three pairs of legs. Source:
To see examples
of the various insect families go to insect
See the pictures
of all Zambian Butterflies by clicking on
the collage below
a class (Arachnida) of joint-legged invertebrate animals
in the subphylum Chelicerata. All arachnids have eight legs, although
in some species the front pair may convert to a sensory function. The
term is derived from the Greek word ἀράχνη (aráchnē), meaning "spider".
Almost all extant arachnids are terrestrial. However, some inhabit
freshwater environments and, with the exception of the pelagic zone,
marine environments as well. They comprise over 100,000 named species,
including spiders, scorpions, harvestmen, ticks, mites and Solifugae. Source:
Arachnids occurring in