This picture was taken during our crayfish dissection. Crayfish are crustaceans. The gills are the fleshy, feathery parts along the side of the crayfish. They are used to breathe in the water. They are in this class because of their 8 legs.
Spiders have special chelicerae which have been modified as fangs for feeding.
They have spinnerets in the abdomen to spin the webs which are characteristic of spiders.