Spiders
Spiders belong to the classification of arachnids which is a kind of arthropod. The structures that comprise the cellular masses of a spider's nervous system can be almost entirely found in the spider's cephalothorax, with just a few minor ganglia in the abdomen. The supraoesophageal ganglion positioned just above the digestive tract serves as the spider's brain. The brain is meant to process sensory information mostly from the eyes to produce suitable responses to a certain situation. Spiders like grasshoppers, have sensory organs meant to feel what goes on around them. Spiders also have tiny hairs on their legs similar to the hairs in a human's ear meant to pick up the vibration in the air to be converted to electric signals which we know as sound.