Nervous System
Jellyfish have no brain nor central nervous system, but employ a loose network of nerves, located in the epidermis, which is called a "nerve net". A jellyfish detects various stimuli including the touch of other animals via this nerve net, which then transmits impulses both throughout the nerve net and around a circular nerve ring, through the rhopalial lappet, located at the rim of the jellyfish body, to other nerve cells.
Another counter to the "brainless jellyfish" hypothesis is that some species explicitly adapt to tidal flux to control their location. In Roscoe Bay, jellyfish ride the current at ebb tide until they hit a gravel bar, and then descend below the current. They remain in still waters waiting for the tide to rise, ascending and allowing it to sweep them back into the bay. They monitor salinity to avoid fresh water from mountain snowmelt, again by diving until they find enough salt.
Famous quotes containing the words nervous system, nervous and/or system:
“A car can massage organs which no masseur can reach. It is the one remedy for the disorders of the great sympathetic nervous system.”
—Jean Cocteau (1889–1963)
“I can’t accept “our nervous age,” since mankind has been nervous during every age. Whoever fears nervousness should turn into a sturgeon or smelt; if a sturgeon makes a stupid mistake, it can only be one: to end up on a hook, and then in a pan in a pastry shell.”
—Anton Pavlovich Chekhov (1860–1904)
“Hence, a generative grammar must be a system of rules that can iterate to generate an indefinitely large number of structures. This system of rules can be analyzed into the three major components of a generative grammar: the syntactic, phonological, and semantic components.”
—Noam Chomsky (b. 1928)