Crustaceans and Insects BELONG TO THE PHYLUM ARTHROPODA but have their own characteristics as listed below:
All insects must have:
three body parts - a head, thorax, and abdomen
six jointed legs
two antennae to sense the world around them
an exoskeleton (outside skeleton)
If all four of these things are not true, then the animal can't be called an insect! Spiders are not insects because they have eight legs and don't have three body parts. Centipedes and millipedes have way too many legs to be called insects! Most insects have one or two pairs of wings, but wings aren't necessary to be classified as an insect.
Scientists believe that insects are so successful because:
they have a protective shell or exoskeleton
they are small
most of them can fly.
Their small size and ability to fly helps them to escape from enemies and travel to new environments. Because they are small they need only small amounts of food and can live in very small cracks and spaces. Insects can also produce large numbers of offspring very quickly
Some Characteristics of Crustaceans:
A hard exoskeleton made of calcium - no internal skeleton.
The head has two compound eyes, two pairs of antennae, and three pairs of mouthparts.
A pair of green glands excrete wastes near the base of antennae.
The abdominal segments have swimmerets (swimming legs)
The sexes are separate. Eggs are attached to the swimmerets (swimming legs) of the female. The first pair is enlarged in the male (it is used to pass sperm to the female).
The tail is fan-shaped, and ends in uropods and a telson.
The circulatory system is open; there is no heart and the "blood" is pumped by vessels into sinuses, and does not flow in a closed loop).
The nervous system consists of a primitive ventral nerve cord and ganglia system (similar to those of an earthworm).
· 1 decade ago