-over a million species and 10000000000000000000 individuals

   -eucoelomate

   -bilateral

   -mostly have three different segments; head, thorax, abdomen

   -have joined appendages

   -exoskeleton made of citin and will molt to grow

 Most insects have highly branched trachial tubes that goes to every cell. They have spiracles and no lungs. Aquatic anthropods have gills: outfoldings of the ectoderm. Spiders have lungs which are infoldings of the ectoderm.

 Sensory organs:

   -more complex and well developed

   -pheromones

   -chemoreception

   -vision is simple compound eye

 They have

   -well developed nervous system with ganglia

   -open circulatory system

   -malpigian tubes
   -mouth, stomach, intestine, rectum
   -mostly seperate sexes: water anthropods have external fertilization, land anthropods have internal fertilization

 

Classes

   Class Arachnida includes spiders, scorpians, and ticks and all lack mandables. They have six pairs of walking legs except ticks and mite which have one and all have four pairs of walking legs.

   Class Crustacea includes lobster, shrimp, crabs, barnacles, and daphnia. They have 2 pairs of atennae and usually five pairs of walking legs.

   Class Chilopoda are the centipedes and have one leg per segment. They are fast, carnivorous and venomous.

   Class Diplopoda are the millipedes with two legs per segment. They are slow, but some species can get very large. When threatened they produce a unpleasant smelling gas.

   Class Insecta includes flies, miquitoes, dragon and butterflies, wasps and hornets, bettles, and moths. They go through metamorphosis and have internal fertilization.