Balella mirabilis
| Balella mirabilis | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name of the family | ||||||||||||
| Balellidae | ||||||||||||
| Stechow , 1922 | ||||||||||||
| Scientific name of the genus | ||||||||||||
| Balella | ||||||||||||
| Stechow , 1919 | ||||||||||||
| Scientific name of the species | ||||||||||||
| Balella mirabilis | ||||||||||||
| ( Nutting , 1905) |
Balella mirabilis is a species of the hydrozoa (Hydrozoa) with a polyp and medusa stage . It is the only species of the genus Balella , which in turn is the monotypic family Balellidae .
features
The hydroid polyp colonies are mostly upright and reach about 6 cm in height. However, the side branches mainly expand in one plane. The network of fine stolons forms a large tangle (hydrorhiza) that anchors the colony in the sediment. upright. The polyps are polymorphic; H. differentiated into feeding polyps (gastrozoids), sex polyps (gonozoids) and defense polyps (dactylozoids). The feeding polyps are up to 1.2 mm high; they preferably sit on the top and bottom of the side branches in a wide and flat cup. The short, pear-shaped body of the feeding polyp sits on a long, slender, stem-like lower part. The nipple-like cone of the mouth (hypostome) is relatively high. There are two tentacle wreaths clearly separated from each other, each with about 10 thread-like tentacles. The lower rim sits at the base of the (pear-shaped) swelling of the polyp, the upper rim at the base of the mouth cone. The tentacles become somewhat thinner towards the tip; they are evenly occupied with nettle cells. The sexual polyps are only about half the size of the feeding polyps. They are very slender and slightly swollen at the top (or distal) end. The base is in a short, tubular perisarc collar. At the distal end a single thin tentacle, which can also be missing. At about a third of the height from the distal end there is a wreath of four to six Medusa buds. The defense polyps are relatively numerous and regularly distributed over the colony. They are finger-shaped without a perisarc collar. The epidermis of the defense polyps is only covered with a few Euryteles . The Medusa buds measure up to about 0.25 mm. The oldest medusa stage observed so far had four radial canals. There are four buds on the edge, each with a thick epidermis and a short tentacle. The manubrium is relatively simple with no gonadal tissue. The nettle cells are desmonemes and microbasic eurytele .
Geographical occurrence
So far there are only a few records of this type, but they are scattered over a large area in the Pacific. The type locality lies between the Hawaiian islands of Molokai and Maui at a depth of 232 m. Later it was detected in the Kai Islands (also Kei Islands) in the Indonesian archipelago before Japan . The evidence so far lies in a water depth of 49 to 232 m on sandy or muddy subsoil.
Systematics
A second species of the genus ( Balella irregularis (Fraser, 1938)) is considered by Schuchert (2003) as a younger synonym of Balella mirabilis .
swell
literature
- Marymegan Daly, Mercer R. Brugler, Paulyn Cartwright, Allen G. Collin, Michael N. Dawson, Daphne G. Fautin, Scott C. France, Catherine S. McFadden, Dennis M. Opresko, Estefania Rodriguez, Sandra L. Romano & Joel L. Stake: The phylum Cnidaria: A review of phylogenetic patterns and diversity 300 years after Linnaeus. Zootaxa, 1668: 127-182, Wellington 2007 ISSN 1175-5326 Abstract - PDF
- Peter Schuchert: Hydroids (Cnidaria, Hydrozoa) of the Danish expedition to the Kei Islands . Steenstrupia, 27 (2): 137-256, Copenhagen, 2003. ISSN 0375-2909 PDF