The nervous system of this original multicellular animal is organised in an elementary nerve net
that is already capable of simple behaviour patterns.
In scyphozoans, two parallel subumbrellar systems were found based on immunohistochemical staining: one associated with the swim motor system (giant fiber nerve net
, also called the motor nerve net
: Passano, 1965; Anderson and Schwab, 1981; Satterlie and Eichinger, 2014), and one with a sensory/modulatory network called the diffuse nerve net
(Passano, 1965; Anderson et ai, 1992; Gremmelikhuijzen et al.
A network of large neurons was identified as the motor system for coordination of swim contractions (called the Giant Fiber Nerve Net
[GFNN]; Horridge, 1954, 1956a, b).
In cubomedusae, the FMRFamidergic system in the subumbrella is almost exclusively contained within the rhopalia and nerve ring, without the diffuse nerve net
organization seen in scyphomedusae (Satterlie, 2002, 2011).
This, together with immunohistochemical data, suggests that the musculature of the frenula receives the highest density innervation of the motor nerve net
(Coates and Satterlie, in prep.
1K) and processes from these merged with the immunoreactive nerve net
Maintenance and regeneration of the nerve net
The other site of abundant immunoreactivity was the mesogleal nerve net
, a meshwork of neurons and amoebocytes embedded in the collagen-based jelly, the meso-glea, that separates ectoderm from endoderm [ILLUSTRATION FOR FIGURE 6D OMITTED].
Taurine-like immunoreactivity has been reported in the motor nerve net
of the scyphozoan jellyfish Cyanea capillata (Carlberg et al.
1979; Giles and Usherwood, 1985), has recently been shown to depolarize neurons in the motor nerve net
(MNN) of the scyphozoan jellyfish Cyanea capillata (Anderson and Trapido-Rosenthal, 1990).
The general theory: The oldest animals were the simplest, and once neural systems emerged, they evolved in a straightforward path from primitive nerve nets
up to complex human brains.
Monochromatic grids of dots are constructed in shades of blue or green, and chain links, nerve nets
, or vaguely floral patterns cover small wood panels.