Слайд 2
![Jellyfish and hydra They have very simple nervous system. They](/_ipx/f_webp&q_80&fit_contain&s_1440x1080/imagesDir/jpg/3696/slide-1.jpg)
Jellyfish and hydra
They have very simple nervous system. They don’t have
brain or spinal cord. Just nervous cells.
Слайд 3
![Flatworms Their nervous system is ladder like. At the head](/_ipx/f_webp&q_80&fit_contain&s_1440x1080/imagesDir/jpg/3696/slide-2.jpg)
Flatworms
Their nervous system is ladder like. At the head region, there
are two simple brain like structures, which are called ganglia.
Слайд 4
![Annelids(earthworm) and Arthropods They have segmented bodies, each segment has](/_ipx/f_webp&q_80&fit_contain&s_1440x1080/imagesDir/jpg/3696/slide-3.jpg)
Annelids(earthworm) and Arthropods
They have segmented bodies, each segment has ganglion. Every
ganglion controls own segment. Ventral (lower) nerve cord connects all of ganglia to each other. A simple brain connects sensory organs of head.