Siphonophora: India
This is an extract from |
Note: This article is likely to have several spelling mistakes that occurred during scanning. If these errors are reported as messages to the Facebook page, Indpaedia.com your help will be gratefully acknowledged.
Contents |
Siphonophora
Introduction
Siphonophora are abundant in the tropical seas and constitute an important part of the marine plankton. The monographs on this group arc those of Eschscholtz (1829), Hukley (1859) Haeckel (1888), Lens & Van Riemsdijk (1908), Bigelow (1911), Moser (1925) Bigelow & Sears (1937), Totton (1954, 1965), Stepanjants (1967), and Daniel (1974). The Siphonophora from the Indian Ocean have been studied by several workers -Browne (1926) from Seychelles, Mauritius and Chagos Archipelago; Sundara Raj (1927), LeJoup (1934) and Daniel &Daniel (1963) from the Madras coast; Patriti (1970) from off South East Coast of Africa and Madagascar; Totton (1954) from SE Coast of Africa, SE, NW &S. Indian Ocean, Gulf of Aden, Aqaba and Red sea; Alvarino (1974) from the tropico -equatorial region; Rengarajan (1974) from the West Coast of India; and Daniel (1966, 1974, 1985) from the West and East Coast of India and those collected by R.N. 'Vityaz' along 90° -1100E longitude down. 35°S latitude. In spite of these works there was still a definite paucity of knowledge on the systematics, distribution, abundance and seasonal fluctuation of Siphonophora in the Indian Ocean, sufficient to warrant the publication of a volume on the Siphonophora under the Fauna of India series (Daniel 1985).
There are 180 (valid and 17 doubtful) species of Siphonophora in the world's oceans. Of these, a grand total of 118 valid, one variety and 3 doubtful species are known from the Indian Ocean. Eighty nine species occur in the Indian Seas.
The study of Siphonophora is beneficial because their occurrence and abundance would indicate not only the movement of the water mass but also the plankton in general. The "Indicator" species like Dimopllyes aretiea indicates the upwelling of rich mid to deep water mass to surface which occurs within (13°N lat to 10°5 lat) the equatorial belt region. Our fisheries depend on the seasonal abundance of the total plankton biomass.
Classification
Phylum Class Order Suborder Families
Cnidaria Hydrozoa S iphonophora Cystonectae Physonectae Calyophorac Physaliidae Rhizophysidae Apolemiidae Agalmidae Pyrostephidae Physophoridae Athorybiidae Rhodaliidae Forskaliidae Prayidae Hippopodiidae Diphydac Clausophyidae Sphaeronectidae Abylidae Ruby Daniel, Zoological Survey of India, Madras
Historical Resume
Pre-1900
The phylum to which the Siphonophora belong is Cnidaria, a name introducedin 1888 by Hatschek, who excluded the Sponges and Ctenophora which had been included in Leuckart's (1847) group Coelenterata. Cuvier (1817) separated the Cnidarians as pmt of two out of the five classes of the last of four primary groups, Zoophytes or Radiata, in his celebrated arrangement of the animal kingdom in Eschscholtz 1829 reorganized the various coelenterate groups which included in Cuvier's third class, Acalephae. He also separated the Ctenophora and Siphonophora, in the latter ofwhich he still included the Chonodrophora of Chamisso &Eysenhardt, 1821, from the Medusae proper (Discophorae). He dealt with about twenty species of Siphnonophotes.
Some of the early detailed systematic work on Siphonophores was done by Eschscholtz (1825-9), Risso (1826), Milne Edwards (1841), Vogt (1851, 1854), Leuckart (1847, 1851, 1853), Gegenbaur (1853a, b) and Kolliker (1853), all of them working on living Mediterranean forms at Nice, Villefranche and Messina. But, of course, many of the earliest names a figures are taken from the Atlases of Voyages of the older naturalists like Lesson (1826) (Voyage ... la Coquille, 1822 .. 25), Peron (1807) and Quoy &Gaimard (1824) Voyage ... L' Uranie et la Physicienne, (1817-20). Early contributions were the works of Sars (1846), Will (1844) and Huxley (1859) on Siphonophora collected during his voyage in H.M.S. Rattlesnake. It is worth to mention the following contributions during the previous century: Claus (1860-89), A Agassiz (1865 ..1902), Fewkes (1879-89), Haeckel (1887-89), Chun (1882-1913), Bedot (1882-1909) and Schneider (1896-1900).
Eschscholtz (1829) divided Siphonophora into three suborders : Chondrophorae Chamisso, 1821; Physophorae Eschscholtz, 1829 part, and Calycophorae Leuckart, which was follOWed by ,•Huxley (1859): Chun (1888, 1897b); Haeckel (1888b).
Hacckel's Calyconectae Monogastricae is really the adult or sexual phase (Eudoxid phase) in the life-cycle of the Calyconectae Polygastricae. Similarly, his Physonectae Monogastricae and Cystonectae Monogastticae have been proved to be larval stages in the life history of the Physonectae Polygastricae and Cystonectae Polygastricae respectively. Therefore, these groups have not been recognized by any of the later workers.
ii) 1901-1947
Most of the earlier workers like Lens &van Riemsdijk (1908), Bigelow (1904, 1911b), Browne (1926), Garstang (1946) retained Chondrophorae as one of the tripartite divisions of the Order Siphonophora, though always recognizing the former to be quite distinct in its morphology, relationships and development, i.e. its radial symmetry, with an aboral whorl of simple tentacles, and developing from an 'Actinula' larva (Conaria), and showing close relationship with Tubularinans (specially Corymorpha) in the dominance of a large axial polyp with plexiform aboral Coelentron, aboral wreath of tentacles, free Anthomedusan gonophores and an 'Actinula' larva (Garstang, 1946). The other two suborders, viz. Physophorae and Calycophorae (= Siphonantha Haeckel, 1888; Garstang, 1946) are bilaterally symmetrical, with a separate basal tentacle to each polyp, and developed from a solid 'Planula' larva by unilateml precocious (ventral) budding (Garstang, 1946) and show 'relationship with myriotheline in the resemblance of their lateral paddling bracts to the larval tentacles of the actinula of the hydroid Myriothela, which are aboral in position and locomotive in function.'
Bigelow (1911b), without designating the status of the group clearly (viz., whether a class, or order), recognized four sub-divisions of the Siphonophorae, i.e., Calycophorae, Physopborae, Rhizophysaliae and Chondrophorae.
However, it was Garstang (1946) who after studying the comparative morphology, phylogeny and relationships of Siphonophora, felt that the evolution of Siphonophora had progressed froin a passive flotation, through various combinations of flotation with active modes of locomotion, to a climax of purely muscular methods of swimming and colonial simplification in Calycophorida. He, therefore, reversed the order in which Chun (1897b) and Haeckel (1888b) had arranged the principal groups. He recognized Haeckel' s Disconanthae and Siphonanthae to mark the major gap between the Chondrophorae and the remaining groups. He agreed with Chun in recognizing only two divisions, i.e., Physophorae and Calycophorae under the Siphonophora (= Siphonantba) and in classing Cystonectae and Physonectae (= Amphinecta) under Physophorae (= Physophorida).
iii) 1948-1990
Leloup (1954), after a study of embryology and comparative anatomy, divided the Siphonophora into four groups, i.e., Chondrophorides, Cystonectides, Physonectides and Calycophorides. The first three groups we included under 'Physophorides' However, in 1955 (a, b)he recognized the older names, viz., Calycophorae and Physophorae, and he classified the families Rhizophysidae, Pbysalldae, Velellidae and Porpitidae under Physophorae.
It is interesting to note the gradual increase in the number of species dealt with by systematists. This rose from twenty-six (Huxley, 1859), thirty (Haeckel, 1888), Thirty-two (Lens &, van Riemsdijk, 1908), fifty-two (Bigelow, 1911) fifty-seven (Moser 1925), one hundred and thirty (Totton, 1965), one hundred and fifty (Daniel 1974) to one hundred and eighty (Daniel 1985) known to-day.
Studies from Different Environs
The Siphonophora are holoplanktonic throughout their lives. They do not pass through even a very short fixed larval polypoid stage as in the various hydroids, medusae, and Scyphozoa. Most Siphonophores are stenohaline and cannot tolerate high or low salinities and differences in pressure due to depth and temperature. however, they have a wide distribution in the tropical regions of the oceans.
Siphonophora are restricted to different zones in the ocean. Based on their distribution the species of Siphonophora can be grouped under pleustomic, neritic, oceanic, bathy pelagic and ~tarctic in the ocean. The well known Physalia physalia is the only pleustonic surface species. It occurs in dimorphic foons which are mirror images of each other, i.e. the siphosomal elements occur either on the right or left side of the cresL
There are only four species which are neritic, namely Diphyes chamissonis, Lensia subtiloides Muggiaca atlantica and M. delsmani. The last mentioned species occurs along the coastal regions of India and along the Burma and Malayan coasts. M. atlantica is restricted to the coastal waters of the Arabian peninsula and of the South eastern Africa. Th~ other two species mentioned above do not however confme themselves to the coastal waters. These two are abundantly distributed in the Bay of Bengal.
Oceanic
The oceanic species of Siphonopbora are those that are not influenced by the proximity of the coast (continental shelf-neritic zone), occurring in the 200-0 m depth in the centtal regions of the ocean. The twenty-four species which have bathypelagic disttibution are also oceanic forms that are usually restricted to the depths,• rarely coming to the surface during the upwelling of cold deep waters.
Eleven species (A. okeni, D. dispar, D. bojani, S. chuni, L. hotspur, E. mitra, C. contorta, C. appendiculata, A. tetragona, A. eschocholtzi and B. bassensis) contribute the bulk of the Siphonophore component of the zooplankton of the Indian Ocean, and also are not affected by the thermocline during their vertical immigration, whereas A. rosacea, V. pentacantha, V. glabra. D. arctica. L. multicristata and L. fowleri appear to be restricted by the thermocline during their upward migration (Daniel, 1977).
Dathypelagic species
Except f()r two references on bathymetric range of Siphonophora from the Indian Oc~, nothing is known about the depth range of these mid-and deep-water species (Totton, 1954; Daniel 1974).
There are 16•truly bathypelagic species which do not come up to the surface even during the upwelling of deep cold water mass are as follows: Halistemma amphytridis (1000-0 m); Marrus orthocannoides (1400-700 m) Erenna richardi (1900-1500-100 m); Nectopyramls diomedeae (1600¬650 m); N. thetis (1250-800 m); N. natans (2580~2480; 1650-950 m); N. spinosa (1000-0 m); Lensia hunter (1000-0 m); L. achilles (1400-1000 m); L. cordata (950-650 m); Clausophyes ovala (1350-0 m);Chuniphyes moserae (1260-600 m); C. multidentata (1000-200 m); Crystallophes amygdalina (1650-950, 700 m); Heeteropyramis maculata (1400-250 m); and Thalassophyes crystallina (1400-700, -200 m).
Antarctic
Eighteen species of Siphonophora are known from the Antartica Ocean : Moseria canvoluta, Pyrostephos vanhoeffeni. Marrus antarclius, Rosacea plicata, Vogtia serrata, Diphyes antarctica. Dimophyes arctica, Lensia hardy. L. achilles, L. havock, L. reticulaia. Mugguaea bargmannae. Clausophyes galeala, Chuniphyes moserae. C. multidentata. Crystallophyes amygdalina, Heteropyramis maculala and Thallossophyes crystallina. Of these Moseria convoluta, Pryostephos vanhoeffeni. Diphyes Antartica, Marrus anlarclius are restricted to the Antarctic Ocean. Dimnphyes arctica is considered as a valuable indicator species of deep cold water masses.
Estimation of Taxa
Out of the 15 families mentioned earlier only one family Rhodaliidae is not represented in the Indian Ocean, mainly because the rhodalids are mid to deep water species and no deep water samplings have been done in the Indian Ocean. (25°N to 45°S Lat., 200E to 1200E long. During the International Indian Ocean expeditions the plankton collections were made from a depth of 200-0 m except for the collections made by R.V. Vityaz along 91°E long. Wherein collections were made from a depth of 1000-0 m. Most of the deep sea species were recorded from this region except the species belonging to the family Rhodaliidae.
Of the 65 genera known from the world oceans, 19 genera, [Salacella (1 species) and Epidulia (2 species) are doubtful genera] viz. 1ottonia (1 species), Romosia (1 species), Moseria (2.species), Rudjakovia (1 species), Stepanyantsia (1 species), Mica (1 species), Pyrostephos (1 species), AngeJopsis (2 species), Stephalia (3 species), Sagamalia (1 species), Thermopalia (1 species), Rhodalia (1 species), Archangelopsis (1 species), Dromalia (1 species), Prayola (1 species), LUyopsis (2 species) and Slephanophyes (1 species) are not represented in the Indian ocean~
14 families, 45 genera and 120 species are known from the Indian Ocean. Their description, distribution, seasonal variation and abundance were dealt with in the Fauna of India: Siphonophora (Danie11985). Of these, 39 genera and 90 species occur in the Indian seas (2S0N to lOS Lat. ~d 600 E to loooE Long).
Classified Treatment
The Order Siphonophora (Class Hydrozoa) is divided into 3 sub orders and 15 families. The monotypic family Physaliidae is represented by a single species P hysalia physalis with two dimorphic forms common throughout the tropical regions of the 3 major oceans. The family Rhizophysidae is represented by 3 species, RhizophysaJiliJormis, R. eysenhardti and a deep sea Balhyphysa com/era which occurs in the upwelling regions off Java. The family Apolemiidae based on Apolemia uvaria is a deep sea form and comes to the lower boundary of the thermocline in the Indian Ocean. Of the four species of Agalma belonging to Agalmidae three species A. ouni (with 2 dimorphic forms) A. elegans and A. haeckeli (recorded only once) occur in great abundance in the Indian Ocean. Halistemma rubrum is also a common species but H. amphytridis is a rare cold water deep sea form measuring several meters in length and known only from framnents of its polymorphic structure. Cordaga/ma cordiformis, Frillagalma 'Vityazi, Marrus orthocannoides, Lychnagalma utricularia and Erenna richardi are rare species recorded only a few times in the Indian Ocean. Whereas, Nanomia bijuga occurs in abundance along the coasta of India.
Bargamannia elongata belonging to the family Pryostephidae is also a very rare species recorded off Minicoy and Java. The monotypic family Physophoridae with monotypic genus, Physophora hydrostatica occurs allover the Indian Ocean.
The family ALhorybiidae is represented by two genera Alhorybia (A. rosacea) and Melophysa (M. melo) and both occur in the Bay of Bengal and near land mass. Of the six species of the genus Forskalia (Family Forskaliidae), F. edwards;, F. leuckarli, F. formosa, F. tholoides and F. cuneata occur in the Indian Ocean and F.formosa, F. tholoides and F. cuneata are rare, recorded 1-3 times off Madras, between Madagascar and and S. Africa and near Nicobar Islands. F. leuckarti is a common species and F. edwards; is a cold mid-water species which comes up during upwelling of deeper waters and occurs ncar the sub-antartica convergence belt in the Indian Ocean.
The suborder Calycophorae consists of 6 families, 28 genera and 93 species. Of these 52 are mre species recorded only a few times during the International Indian Ocean Expedition. The remaining common species occur in great abundance and fonn the bulk of the zoological constituent of the plankton. In spite of the extensive collections made during the International Indian Ocean Expedition (1.1.0.E. -1960, 1962-1965) by the nineteen Research vessels from nine countries (from 200-0 m depth) no representitive of the entire family Rhodaliidae (7 genera and 10 species) was recorded from the Indian Ocean.
Detailed information on histology (taxonomic characters), biology, physiology, reproduction, embryological and early development (larval) of many species, genetics (chromosomes) and their bearing on taxonomy are still needed. It is hoped that future workers would take up such studies so as to get a complete knowledge of this group of animals.
Expertise India
In ZSI
R. Daniel, Research Associate, Marine Biological Station, Zoological Survey of India, 100, Santhome High Road, Madras -600 028.
Elsewhere
K. Rengarajan, Centnll Marine Fisheries Research Institute, Emakulam, Kerala.
Abroad
R. Va. Margulis Biological Faculty, Chair of Invertebrates, State University of Moscow Moscow, W -234 USSR. P.R. Pugh, Institute of Oceanographic Sciences, Natural Environment Research Council Wormley, Golalming, Survey, GU8, 5 UB, UK. Zhang Jinbiao, Third Institute of Oceanography, National Bureau of Oceanology, Arnoy, China XU Zhen ZU, Oceanology Department, Arnoy University, China.
Selected References
Aivarino, A. 1971. Siphonophores of the Pacific with a review of the world distribution. Bull. Scripps InsI. Oceanogr. 16 : 432 pp.
Daniel, R. 1974. Siphonophora from the Indian Ocean. Mem. zool. Surv.lndia, XV, No.4, pp. 1-242, 18 text-figs.
Daniel, R. 1985. Fauna of-India. Coelenterata: Hydrozoa: Siphonophora. Zoological Survey of India, 1-240, pp. 120 figs, 127 maps. . Lens, A.D. &Van Riemsdijk, TH, 1908. The Siphonophora of the "Siboga" Expedition -Siboga Exped., 9 : 1-130, pp. 24 pIs. 52 figs.
Pugh, P.R. 1983 : Benthic Siphonophores : A review of the family Rhodallidae (Siphonophora, Physonectae) Phil. Trans, R. Soc. Lond., B 301, 165-300, pp. Fig. 1-44. (pIs. 1-6). Sears, M. 1953. Notes on Siphonophores 2. A revision of the Abylinae. Bull. Mus. Compo %001. Ifarv., Cambridge, Mass, 109 (1), 1-199, pp. 29 text-figs. Totton, A.K. 1954. Siphonophora of the Indian Ocean, together with systematic and biological notes on related species from other oceans. Disc. Rep., Cambridge, 27, 1-161, pp. 12 pIs., 83 text figs.
Totton, A.K. 1965. A synopsis of the Siphonophora. Publ. by the Trustees of the British Museum (Nat. Hist), London, 1-227, pp. 40 pis., 153 text-figs.
