Animal nervous systems. Artwork of nerves (yellow) in animals during evolution. The first primitive nervous systems were nerve nets in organisms with radial symmetry such as jellyfish and comb jellies (top). This was followed by the development of bilateral symmetry,nerve cords,and a primitive brain (grouping of ganglia) in a worm-like animal from the Ediacaran period (550-600 million years ago). Below that is a lobster (a crustacean) with the ventral nerve cord along its abdomen typical of arthropods. The vertebrate nervous system is shown for a lizard (bottom),marking the emergence of a spinal cord and a true brain | |
Lizenzart: | Lizenzpflichtig |
Credit: | Science Photo Library / Jensen, Mikkel Juul |
Bildgröße: | 2646 px × 3307 px |
Modell-Rechte: | nicht erforderlich |
Eigentums-Rechte: | nicht erforderlich |
Restrictions: | - |