Rhopalia
Encyclopedia
Rhopalia are small sensory
structures of Scyphozoa
(typical jellyfish) and Cubozoa (box jellies). In Aurelia
they lie in marginal indententions around the bell and are flanked by rhopalial lappets. Specialized structures to sense light (ocelli
) and perceive gravity (statoliths) are usually present. They also control the pace of swimming-muscle contraction.
Cubozoan ocelli are the most complex of Cnidarians, and resemble the image-forming eyes of squid
, octopus
es, and vertebrate
s.
Sense
Senses are physiological capacities of organisms that provide inputs for perception. The senses and their operation, classification, and theory are overlapping topics studied by a variety of fields, most notably neuroscience, cognitive psychology , and philosophy of perception...
structures of Scyphozoa
Scyphozoa
Scyphozoa is a class within the phylum Cnidaria, sometimes referred to as the "true jellyfish".The class name Scyphozoa comes from the Greek word skyphos , denoting a kind of drinking cup and alluding to the cup shape of the organism....
(typical jellyfish) and Cubozoa (box jellies). In Aurelia
Aurelia (genus)
Aurelia is a genus of scyphozoan jellyfish . There are at least 13 species in the genus Aurelia including many that are still not formally described...
they lie in marginal indententions around the bell and are flanked by rhopalial lappets. Specialized structures to sense light (ocelli
Ocellus
A simple eye refers to a type of eye design or optical arrangement that contains a single lens which detect light. A "simple eye" is so-called in distinction from a multi-lensed "compound eye", and is not necessarily at all simple in the usual sense of the word...
) and perceive gravity (statoliths) are usually present. They also control the pace of swimming-muscle contraction.
Cubozoan ocelli are the most complex of Cnidarians, and resemble the image-forming eyes of squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...
, octopus
Octopus
The octopus is a cephalopod mollusc of the order Octopoda. Octopuses have two eyes and four pairs of arms, and like other cephalopods they are bilaterally symmetric. An octopus has a hard beak, with its mouth at the center point of the arms...
es, and vertebrate
Vertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...
s.