Question

A jellyfish is a type of cnidarian, a squid is a type of mollusk, and a dolphin is a type of vertebrate. Which two characteristics are present in both a squid and a dolphin, but not present in a jellyfish?

Answer 1

Jellyfish do not have a central nervous system.

Squids which belongs to Cephalopoda (class of Mollusca) have the most complex nervous system of the invertebrates. They have well-developed senses and large brains. So, they are considered as the most intelligent of the invertebrates.

Dolphins, on the other hand, are  regarded as one the most intelligent animal.