Arthropoda

Arthropoda

The Phylum Arthropoda is the most successful group of animals on earth. Arthropods are found in many habitats. They are found in diverse land environments, in the sea, and they can float or fly in the air. It is thought 75-90 % of all known living and fossil organisms (estimated at over 1 million species), are arthropods.    
  
 The success of the Arthropoda as a group is related to their hard exoskeleton made of chiton which not only provides protection, but also stops them from dryng out (dessicating). The exoskeleton is shed  and the animal grows before the new exoskeleton hardens.  To enable movement, the arthropod body is divided into segments, and legs (used for movement, feeding, defence and sensing changes in the environment), which are jointed.

They range in size from microscopic plankton (0.25 mm) up to giant crabs several metres long. The largest living arthropod is the Japanese spider crab, with a leg span up to 3.5 m (12 ft), 

Arthropods include:

• Hexapoda (with six legs): insects and closely related groups.  About 20,000 species in New Zealand.
• Arachnida (with eight legs): spiders, harvestmen, scorpions, false-scorpions, mites, ticks.  About 3,500 species in New Zealand.
• Myriapoda (with many legs): centipedes, millipedes, and allies.  About 250 species in New Zealand.
• Pycnogonida (with very small body and usually have 4 pairs of legs but some species with 5 or 6 pairs): sea-spiders (only distantly related to terrestrial spiders).  About 90 species in New Zealand.
• Crustacea (with six to many legs): shrimps, crabs, prawns, and allies.  About 3,000 species in New Zealand.

At Te Papa, the Crustacea and Pycnogonida are managed as part of the Crustacean Collection.