Description

22. ix. 2003, Near Farol dos Moleques, Canal de São Sebastião, 23 ° 49 ' 27 " S 45 ° 24 ' 42 " W, O. M. P. Oliveira coll., three juveniles (5 – 11 mm in width), one reared to 13. x. 2003, other reared to 23. x. 2003, Fig. 5 D; 31. xiii. 2004, Near Ponta da Sela, Canal de São Sebastião, 23 ° 52 ' 18 " S 45 ° 27 ' 17 " W, O. M. P. Oliveira coll., one juvenile (ca. 12 mm in width), very damaged, preserved in 95 % ethanol; 27. xi. 2004, Baía do Segredo, Canal de São Sebastião, 23 ° 49 ' 27 " S 45 ° 25 ' 19 " W, ca. 10 adults (up to 50 mm in width), observed during snorkelling; 27. xi. 2004, Baía do Segredo, Canal de São Sebastião, 23 ° 49 ' 27 " S 45 ° 25 ' 19 " W, O. M. P. Oliveira coll., two adults (36 – 48 mm in width), preserved in 95 % ethanol. Description Body compressed along tentacular plane, translucent milky white in color, with two well­developed oral lobes arising between apical organ and mouth (Fig. 5 A). Lobes with strong musculature. Polar field elongated at stomodeal axis, with apical organ at center of aboral extremity of body (Fig. 5 C). Wide comb plates arranged in short rows, with up to 25 plates in stomodeal rows of adults. Subtentacular rows of comb plates reaching ca. 2 / 3 length of substomodeal rows. Flattened pharynx with constriction at half its length, opening into a wide, prehensile mouth. Axial and oral tentacles absent. Tentilla absent along mouth margin. Gonads formed at walls of substomodeal meridional canals from oral extremity of comb plates to near extremities of lobes. Juvenile with 1 – 3 comb plates in each row and two tentacular bulbs, each associated with a branching, extendable axial tentacle. Biological notes Ocyropsis crystallina, a typical inhabitant of oceanic waters (Harbison & Miller, 1986), is apparently uncommon in southeastern Brazilian coastal waters. These cteno­ phores are able to swim relatively fast in escape situations, moving the lobes as if they were “ flying ” in the water. The lobes help in the hunting process: the comb beats give propulsion, the animal moves with its oral end forward and the lobes capture and handle the prey, transporting it to the mouth. Harbison et al. (1978) described the feeding behavior, stressing that the species feeds on siphonophores, other ctenophores, pteropods, large copepods, small fishes, amphipods, and euphausiids. In the laboratory, we observed that a juvenile of this voracious ctenophore is able to turn its mouth toward the prey and ingest many Artemia nauplii in a few minutes, until the pharynx is filled up with nauplii. This juvenile, collected in a plankton tow, was 12 mm in width and used its tentacles to capture prey. This specimen was reared in the laboratory for four weeks. After the first ten days, it lost the tentacles, and only traces of the tentacular bulbs remained (Fig. 5 D). During this period, there was a gradual change in juvenile feeding strategies, from a technique in which the axial tentacles were employed to capture prey to the one in which the oral lobes played the main role in the process of capturing and handing prey. The specimen was preserved after four weeks, when it had reached 17 mm in width.

Common Names

Taxonomic Hierarchy

Kingdom: Animalia

Phylum: Ctenophora

Class: Tentaculata

Order: Lobata

Family: Ocyropsidae

Genus: Ocyropsis

Species: Ocyropsis crystallina (Rang, 1827)