feeling
Antennules are for smell. Antenna are tactile.
The Antennules in a Crayfish, being short while the Antennas are long, are used to taste food.
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The antennules and antennae
There is no difference between an antennule and antennae. An antennule is just a small antennae. Antennules are basically the same, but just in size that they vary. They both have the same purposes, the antennae is the plural form of saying the bigger antenna.
The Antennules in a Crayfish, being short while the Antennas are long, are used to taste food.
The crafish's antennules are the smaller antennas and they aid in balance and provide taste and touch. The larger antennas called the antennae are much more sensative then the antennules, providing the crayfish stronger sense of taste and touch.
A statocyst at the base of each antennule enables the crayfish to keep its balance.
The crustaceans are arthropods with biramous (branching) appendages, including a larger and smaller pair of antennae, the smaller ones being referred to as antennules.
On crustaceans there will seem to be two pairs. They are actually biramous (branching) with the smaller pair called antennules. Most other arthropod groups have one pair; some have none (like the arachnids).
Crustaceans are arthropods characterized (and classified) by their biramous (branching) appendages, which include two antenna pairs. The smaller set are referred to as antennules. All other arthropod groups have one pair except chelicerates and proturans, which have no antennae.