Within the phylum Cnidaria, class Hydrozoa, order Anthoathecata and family Tubulariidae we find the species Ralpharia gorgoniae. It is a solitary polyp that we will find clinging to various species of gorgonians in the waters of the Caribbean Sea, where it is believed to be endemic. It is a species that is rarely found in waters deeper than 15 meters.
The body of Ralpharia gorgoniae consists of two distinct parts. On one side we find an elongated trunk that is covered by a tubular calcareous secretion and at the end of which the gorgonia tissue clings firmly. At the opposite end, we find a crown formed in its outermost part by 20-21 elongated tentacles with curly ends and reddish color. Inside the crown, and going in the direction of the mouth opening, we find during the breeding season of this species, 8 branched structures with glomeruli that resemble bunches of grapes. Finally, and surrounding the mouth opening, we find about 50 short filiform tentacles. In total, Ralpharia gorgoniae specimens can reach a height of about 3-4 cm, and 1-1.5 cm in diameter.
The feeding of Ralpharia gorgoniae is carnivorous in nature, capturing with its tentacles loaded with stinging cells its prey, among which we find zooplankton and even some small fish larvae.
Although we can usually observe the polyp phase of Ralpharia gorgoniae, its life cycle includes a jellyfish phase of very short duration and very small size. These jellyfish do not have tentacles, but are formed only by a translucent bell. It is a dioecious species, meaning that each specimen of this species is either male or female.
There is great confusion within this family of hydroids, since there have been numerous scientific works based on very few specimens and with little comparative information, so in many cases we could be facing specimens of the same species but with significant differences in shape, color or size.Photos: