The mesencephalon gives rise to the midbrain and aqueduct of
the midbrian(cerebal aqueduct). Both the prosencephalon and rhombencephalon
develops in to the metencephalon and myelencephalon. The telencephalon develops into the cerebrum
and lateral ventricles. The diencephalon forms the thalamus, hypothalamus, and
epithalamus.
Cells are the basic building blocks of life, which can join together to form tissues, while different groups of tissues join together to form organs. These organs are then connected together to form organ systems , such as the digestive system , which includes the stomach , esophagus , intestines and other organs .
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.
