Jellyfish Nausithoe
Nausithoe punctata
Scyphozoan cnidarians are characterized by a polyp * phase restricted to absent. If it is mostly easier to observe a jellyfish in the open water than to find and observe the polyp that gave birth to it. The case of Nausithoe punctata, on the other hand, will pose the opposite problem: it is much easier to find the polyp phase than the jellyfish phase!
The polyp phase:
The polyps of Nausithoe punctata form colonies sometimes covering a large area.
They have the shape of narrow and elongated small cones not visible because they are deep encased in the pores of different species of sponges. These horns have real chitinous skeletons, hard to the touch, whose edges are white and thick. From the top of each of them, flourishing at the surface of the sponge, radiations of about fifty fine tentacles can be observed. In the middle of each of them a mouth opens that is partitioned in a characteristic manner by four gastric perpendicular septa. The diameter at the neck reaches one centimeter, the length of the cornets five centimeters. The polyps are whitish to transparent.
The jellyfish phase:
The jellyfish of Nausithoe punctata has a diameter of not more than 15 millimeters, which is very small for a scyphoe, and which explains, in addition to the fact that it is transparent and usually deep, that it is so rarely observed. Its parasol is flattened, and traversed by a transversal groove which cuts it in two (characteristic of the Coronates order). The top of the parasol forms a thick lens, its margin is fringed with 16 hollow lobes, evoking small spoons, each marked by a small brown spot. Between each of these lobes alternate alternately 8 rhopalies * and 8 short tentacles. Under each tentacle there is a small orange-brown to red sphere: these are the gonads. Under the umbrella opens a mouth on the cross, at the end of a manubrium * very short.
Offshore. Abundant in warm waters. Feeds on zooplankton. Members of the class Scyphozoa are gonochoric. Life cycle: Egg is laid by the adult medusa which later develops into a free-living planula, then to a scyphistoma to a strobila, and lastly to a free-living young medusa.
Distribution: Circumglobal.
The polyp phase:
The polyps of Nausithoe punctata form colonies sometimes covering a large area.
They have the shape of narrow and elongated small cones not visible because they are deep encased in the pores of different species of sponges. These horns have real chitinous skeletons, hard to the touch, whose edges are white and thick. From the top of each of them, flourishing at the surface of the sponge, radiations of about fifty fine tentacles can be observed. In the middle of each of them a mouth opens that is partitioned in a characteristic manner by four gastric perpendicular septa. The diameter at the neck reaches one centimeter, the length of the cornets five centimeters. The polyps are whitish to transparent.
The jellyfish phase:
The jellyfish of Nausithoe punctata has a diameter of not more than 15 millimeters, which is very small for a scyphoe, and which explains, in addition to the fact that it is transparent and usually deep, that it is so rarely observed. Its parasol is flattened, and traversed by a transversal groove which cuts it in two (characteristic of the Coronates order). The top of the parasol forms a thick lens, its margin is fringed with 16 hollow lobes, evoking small spoons, each marked by a small brown spot. Between each of these lobes alternate alternately 8 rhopalies * and 8 short tentacles. Under each tentacle there is a small orange-brown to red sphere: these are the gonads. Under the umbrella opens a mouth on the cross, at the end of a manubrium * very short.
Offshore. Abundant in warm waters. Feeds on zooplankton. Members of the class Scyphozoa are gonochoric. Life cycle: Egg is laid by the adult medusa which later develops into a free-living planula, then to a scyphistoma to a strobila, and lastly to a free-living young medusa.
Distribution: Circumglobal.