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The concave underside of the medusa of a jellyfish or other cnidarian.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


the muscular and concave underside of the umbrella of a jellyfish
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(ˌsʌb ʌmˈbrɛl ə)

n., pl. -las.
the concave undersurface of a jellyfish.
sub`um•brel′lar, adj.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
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The striated swim musculature of the subumbrella has previously been described (Satterlie et al., 2005) and is responsible for the strong, efficient swimming contractions characteristic of this group (Stewart, 1996).
Manubrium broad, filling most of subumbrella cavity, mouth simple.
subumbrella (Dyar) in the Prairie Provinces demonstrates the value of regional collections and species lists.
Treated flower/fruits that were attacked by the caterpillar (Lepidoptera, Pyralidae: Olycella subumbrella) were counted to estimate florivory and the pollination treatment was repeated on a new flower.
The swim system includes a cluster of pacemaker cells in each rhopalium; a conducting system in the nerve ring, which links the rhopalial pacemakers but also distributes excitatory impulses to the subumbrella; and a subumbrellar motor nerve net, which synaptically activates the circular muscle that lines the bell cavity (Satterlie, 1979; Eichinger and Satterlie, 2014).
Recent morphological evidence supports the presence of two separate nerve nets in the subumbrella of scyphomedusae (e.g., Anderson and Schwab, 1981; Anderson et al., 1992; Carlberg et al., 1995).
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).
Consequently, stopping vortex formation inside the subumbrella was inhibited and only the starting vortex, characteristic of jet propulsion, was available for thrust production.
Family Cyaneidae is distinguished from other semaeostome families on the basis of three characters: in cyaneids, tentacles arise from the subumbrella away from the bell margin, pendulous gonads hang below the subumbrella in complexly folded eversions of the subumbrellar wall, and the stomach forms radiate pouches that terminate in rudimentary (i.e., poorly developed) branching canals only in the marginal lappets (Kramp, 1961: p.
Capture locations were visible for all major surfaces (lappets, subumbrella, oral arms, and tentacles) during the course of medusan development.
Four morphological features set the cubomedusan velarium apart from the hydrozoan velum and suggest that the velarium is derived from scyphozoan-like marginal lobes (Conant, 1898; Gladfelter, 1973): (1) the velarium is penetrated by gastric canals (never in the velum); (2) swim musculature of the velarium is continuous with that of the subumbrella; (3) the velarium, unlike the velum, does not possess exumbrellar radial muscle; (4) four bracket-like frenula support the velarium in the perradii.
The MNN extends over the entire subumbrella surface, forming a network that connects all eight marginal ganglia, or rhopalia, with the circular and radial swimming muscle bands.