Dr. John Turnbull, Marine Explorer, Australien
Info
Hydrozoons are tubular predatory polyps that are related to jellyfish.
Most hydroids live colonially, but Ralpharia magnifica occurs as a single animal in small groups of up to 20 animals.
Ralpharia magnifica forms sparse colonies that develop from a tubular hydrorrhiza embedded in the host substrate.
Diameter of the hydrorrhiza up to 1 mm.
Tentacles:
Aboral tentacles 27- 40 in number, up to 30 mm long, arranged in a single whorl and up to 150 oral tentacles of 1-5 mm length, clustered in a dense tuft 5-6 rows deep around the mouth.
The hydroids are effective predators, small crustaceans have often been found in their stomachs, and on one occasion a small fish about 1 cm long was observed to be swallowed.
The gonophores of both sexes are identical in shape and size, but are carried by different branches, and are tied to the blastostyle with a short, wrinkled stem.
Hydrozoons are often called "sessile" cnidarians, in the case of Ralpharia magnifica this description can be discussed, because the hydrozone is rather an epiphyte, which in the sessile stage mainly, the first description assumes "exclusively", populates the jug coral Parerythropodium membranaceum (Kukenthal, 1906).
Colour: Stem greenish-brown with dark brown perisark on the lower stem and hydrorhiza, Coenosark flesh pink. Tentacles translucent white, body of hydrorhiza pink,
Blastostyle white, the maturing gonophores are orange-brown.
On release, a jelly of transparent medusas is released into the water.
Most hydroids live colonially, but Ralpharia magnifica occurs as a single animal in small groups of up to 20 animals.
Ralpharia magnifica forms sparse colonies that develop from a tubular hydrorrhiza embedded in the host substrate.
Diameter of the hydrorrhiza up to 1 mm.
Tentacles:
Aboral tentacles 27- 40 in number, up to 30 mm long, arranged in a single whorl and up to 150 oral tentacles of 1-5 mm length, clustered in a dense tuft 5-6 rows deep around the mouth.
The hydroids are effective predators, small crustaceans have often been found in their stomachs, and on one occasion a small fish about 1 cm long was observed to be swallowed.
The gonophores of both sexes are identical in shape and size, but are carried by different branches, and are tied to the blastostyle with a short, wrinkled stem.
Hydrozoons are often called "sessile" cnidarians, in the case of Ralpharia magnifica this description can be discussed, because the hydrozone is rather an epiphyte, which in the sessile stage mainly, the first description assumes "exclusively", populates the jug coral Parerythropodium membranaceum (Kukenthal, 1906).
Colour: Stem greenish-brown with dark brown perisark on the lower stem and hydrorhiza, Coenosark flesh pink. Tentacles translucent white, body of hydrorhiza pink,
Blastostyle white, the maturing gonophores are orange-brown.
On release, a jelly of transparent medusas is released into the water.
