Chaetognatha: India
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Faunal Diversity in India: Chaetognatha
This is an extract from FAUNAL DIVERSITY IN INDIA Edited by J. R. B. Alfred A. K. Das A. K. Sanyal. ENVIS Centre, Zoological Survey of India, Calcutta. 1998 ( J. R. B. Alfred was Director, Zoological Survey of India) |
Introduction
Chaetognatha popularly known as "Arrow-worms" or "Glass-worms" constitute one of the major components of the marine plankton. They are mostly marine, but a few are estuarine. They are bilaterally symmetrical carnivores with a head, trunk and tail. The head has a set of lateral hooks, teeth, eyes and a mouth followed by a trunk filled with fluid. The trunk has a gut and the female gonad. The male gonad is situated in the tail segment. The trunk and tail are separated by a tail septum. Excretory and circulatory systems are absent. They have an elaborate nervous system with six ganglia in the head and a large ventral ganglion in the trunk. Chaetognaths playa main role in the food cycle and well known as indicator organisms of watermasses and their movements.
Status Of The Taxon Global Status
Chaetognaths were first reported as 'Sea-worms' by Martin Slabber in 1778 and the next information about these 'worms' was published only in 1827 by Quoy and Gaimard. Though there are a few papers on this group after 1827, a complete revision was done only in 1911 by Ritter-Zahony. He recognised 27 species in six genera. Later, Tokioka (1965) listed 58 species in 15 genera and recently Bieri (1991) reported 111 valid species in 23 genera. Out of these, 22 species are benthic and the remaining 89 are pelagic.
Indian Status
Out of III species reported from the World Oceans, 30 species are so far known from the epi-, meso-, and bathy-planktonic waters of the Indian seas.
Distribution
Chaetognatha are seen at the surface, sub-surface and bottom of the sea. Based on the pattern of distribution they could be classified as cosmopolitan, Indo-pacific and endemic species.
Cosmopolitan species: Genus Sagitta: S. bipunctata, S. decipiene, S. enflata, S. gazellae, S. Itexaptera, S. lyra, S. macrocepllala, S. maxima, S. minima, S. tasmanica, S. zetesios; Genus Eukrohnia : E. bathyantarctica, E. fowleri, E. Ilamata; Genus Heterokroltnia : H. mirabilis; Genus Krohnitta : K. pacifica, K. subtilis; Genus Pterosagitta : P. draco. Indo-pacific species Genus Sagitta: S. bedoti, S. ferox, S. neglecta, S. oceania, S. pulchra, S. regularis, S. robusta, S. pacifica.
According to the depth in the ocean in which the chaetognaths are found, they are known as epi-, meso, and bathy-planktonic forms. The following are the epi-planktonic species seen between the surface and 200 metres depth from the surface of the sea. Genus Sagitta : S. bedoti, S. bipunctata, S. bombayensis, S. enflata, S. ferox, S. hexaptera, S. minima, S. neglecta, S. oceania, S. pulchra, S. tropical Genus Krohnitta : K. pacifica and K. subtilis; Genus Pterosagitta : P. draco. The following are the meso-planktonic chaetognaths from the Indian seas found between 200 and 1000 metres depth of the ocean : Genus Sagitta : S. lyra, S. decipiens, S. gazellae; Genus Eukroltnia : E. fowleri, E. hamata and E. minuta; Genus Pterokrohnia : P. arabica. In the Indian seas the following three species found below 1000 metres depth of the ocean are considered as bathy-planktonic. Genus Sagitta : S. macrocephala and S. maxima; Genus Heterokrohnia : H. mirabilis. The following two species of Spadella, viz., S. angulata and S. cepllaloptera are seen attached to the sea weeds at the bottom of the sea in the coastal waters of the Indian seas and they are considered as benthic forms.
Biological Diversity
This is a small phylum with limited number of species. In 1903, Doncaster reported only 11 species from the Indian ocean with 4 new species and in 1906, Fowler listed 16 of the 33 species known from the World Oceans. Then Ritter-zahony (1911) reported the occurrence of 27 species from the Indian Ocean. The number of species known from the Indian seas has gone upto 58 in 1965 (Tokioka) and recently Bieri (1991) listed 111 valid species from the World Oceans and he has stated that the number will increase because many new species remain to be discovered. So it is evident that even in this small phylum, due to biological variations for survival, the number of species has been gradually going up from the then known 33 species from the World Faunal Diversity in India Oceans in 1906 (Fowler) to 111 in 1991 (Bieri). As stated by Bieri (1991) the number of valid species may ultimately reach more than 200.
As pointed out by Bieri (1991), the Chaetognatha now shows a much greater morphological diversity than previously recognized. Owre (1973) described a species of the genus Batllybelos with a dorsal nerve ganglion instead of the usual ventral nerve ganglion. Other interesting morphological diversities are the presence of tubules connecting the ovaries and testes in Heterokrolmia and Archeterokrolmia (Casanova, 1985), occurrence of three sets of teeth in Eukrohnia sinica (Zhang and Chen, 1983), strange seminal vesicles in Pterokrohnia arabica (Srinivasan, 1988) and differences in gut structure (DalIot, 1970). Among the 12 genera reported in this account, the genus Sagitta is the most dominant than the remaining genera and 61 species are known under this genus. When Fowler (1906) reported 16 species from the Indian Ocean, 12 species are known under the genus Sagitta. In 1965 among the 48 species in five genera reported from the World Oceans (Alvarino), 39 species are listed in the genus Sagitta. From these statistics, it is evident that the number of species-in the genus Sagitta has been steadily increasing due to biological diversity.
Endemicity
The three species of the Phylum Chaetognatha, viz., Sagitta bombayensis, Eukrolmia minuta and Pterokrohnia arabica are endemic to the Indian ocean. S. bombayensis was described from Bombay Harbour by Lele and Gae (1936) and later reported from Lawson's Bay, Waltair (Rao, 1958), from Bombay harbour (Silas and Srinivasan, 1968) and from Malayan waters (Pathansali, 1974). E. minuta Was described from the meso-pelagic waters of the Southern Arabian sea by Silas and Srinivasan (1969) and later reported from the deeper waters of the Arabian sea by Srinivasan (1972) and Casanova and Ardrew (1989). P. arabica was described from 900 metres depth off the Northern Arabian sea by Srinivasan (1988).
Value
Chaetognaths playa key role in the food cycle of the marine ecosystem and are of great significance in transferring the energy from copepods to higher trophic levels. The biomass of chaetognaths has been estimated as 10¬30% of that of copepods in the World Oceans (Reeve, 1966). Further they form the food of a wide variety of larger organisms (Bigelow, 1924; David, 1955).
Certain species of Chaetognaths are seen associated with particular type of watermass. This association is useful in identifying a particular type of watermass in a region where there are several water bodies, in which the salinity conditions are not well marked (Russel, 1930). In such cases only the planktonic organisms could provide information on the origin of such waters. Along the west coast of India, Srinivasan (1976, 1996) pointed out the possibility of utilising Sagitta decipiens as an indicator of upwelling. Alvarino (1964, 1967) along the coast of California and Segura et al. (1992) along the Costa Rica, have also reported that this species could be used as an indicator of upwelling. As this is an inhabitant of the waters of low temperature, low oxygen and high salinity, it could be made use to identify the movements of deep waters (Sund, 1961). The presence of S. decipiens, a meso-pelagic species in the epi-pelagic waters of California, Costa Rica and South west coast of India indicates the process of upwelling.
Threats
Polluting the sea water due to oil spillage and dumping the wastage and draining the sewerage water into the sea will affect the hydrography, which ultimately affect the planktonic and other living organisms. These man-made changes will definitely affect the survival of the coastal neritic species than the offshore oceanic species. The reclaimation of the backwaters for construction purposes will also affect these estuarine forms as the estuaries are good nursing grounds. Certain species of Sagitta (5. bedoti, S. enflata and S. aplllcllra) are found in the estuarine waters.
Future Studies
Chaetognaths of the deeper waters of the seas around India are not well known. Further studies on the samples from the deeper waters may increase the number of species known from the Indian seas. Further, seas around the Andaman and Nicobar Islands and central and northern part of the Bay of Bengal are also have to be thoroughly explored as these areas are not studied well for the chaetognath fauna. So, insufficient sampling is mainly responsible for ow ignorance about the unknown species of Chaetognatha from the Indian seas.
Selected References
Alvarino, A. 1964. Bathymetric distribution of chaetognaths. Paci! Sci., 18 : 64-82. Alvarino, A. 1965. Chaetognatha. Oceanogr. mar. BioI. Ann. Rev., 3 : 115-192. Bieri, R. 1991. Systematics of the chaetognaths. In TIle Biology of C/raetognat/lS (Ed.) G. Bone, H. Kapp and A.c. Pierrot Bults Oxford Sci. Pub!. 122-137. Doncaster, L. 1903. Chaetognatha, with a note on the variation and distribution of the group. Fauna and Geography Maldive-Laccadive Arch., 1 : 209-218. Fowler, G. H. 1906. The Chaetognatha of the SIBOGA Expedition with a discussion of the synonym and distribution of the group. Siboga Exped. Monogr., 21 : 1-86. Lele, S. H. and Gae, P. B. 1936. Common Sagittae of the Bombay harbour. J. Univ. Bombay, 4 : 105-113. Pathansali, D. 1974. Chaetognatha in the coastal waters of Peninsular Malaysia with description of two new species. Fish Bull. Min. Agri. Rural Develop., M1llaysia, 2: 1-29. Rao, T. S. S. 1958. Studies on chaetognatha in the Indian seas, 1. The chaetognatha of the Lawson's Bay, Waltair, Andhra Univ. Mem. Oceanogr., 2 : 137-146. Ritter-Zahpony Von 1911. Revision der chaetognathen, Deutc1re Sudpolar Exped., 13 : 1-71. Silas, E. G. and Srinivasan, M. 1969. A new sp~cies of Eulcro/mia from the Indian seas with notes on three other species of Chaetognatha. J. mar. bioI. Ass. India,10 : 1-33. Srinivasan, M. 1976. Distribution of chaetognatha with special reference to Sagitta decipiens as an indicator of upwelling along the west coast of India, J. mar. bioI. Ass. India, 16 : 127-142. Srinivasan, M. 1988. Pterolcrobnia arabica a new genus and new species of chaetognatha from the Arabian sea. J. mar. bioI. Ass. India, 28 : 19-201.
Srinivasan, M. 1996. Spatial and temporal distribution of Chaetognatha from the eastern arabian sea. Proc. Second workshop scient. Result FORV sagar sampada 1966 : 139-148.
Chaetognatha
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Introduction
The Phylum Chaetognatha contains bilaterally symmetrical, carnivorous, mostly marine and a few estuarine species. They form one of the major constituents of the marine zooplankton andplay a prominent role in the food cycle. Chaetognaths are popularly known as "Arrow worms" or "Glass worms" because of the torpedo-like shape and transparent nature of the body. They are well known as indicators of the origin of the watermasses and their movements.
The chaetognaths were frrst reported by Martin Slabber in 1778 from the Dutch coast and he named them as 'Sea worms' Later, Quoy &Gaimard (1827) gave a brief description on the Sagitta species collected from the Straits of Gibraltar. Due to the difficulty of placing Sagitta under the then known groups such as annelids, molluscs etc., Leuckart (1854) proposed a separate group Chaetognatha to accommodate the .Arrow worms and placed them between nematodes and oligochaetes. The terminology of this Phylum is based on the presence of prehensile hooks on either side of the jaws (Chaetae = setae; gnathos = jaws).
The chaetognaths are hermaphrodites, with delicate, elongate, transparent or opaque body and do not have separate respiratory, circulatory and excretory organs. The body is divided into head, trunk and tail. As this is a small Phylum with only a few species and the differences between the species are not marked, no one has thought of dividing the Phylum into Clasges, Orders, Families etc. However, in 1965, Tokioka proposed a new classification for this Phylum as given here:
Phylum CHAETOGNATHA Leuckart, 1854
Class ARCmSAGITOIDEA
Family Amiskwidae (Genus: Amiskwia)
Class SAGITOIDEA
Order 1. PHRAGMOPHORA
Family Spadellidae (Genus Spadella)
Family Eukrohnidae (Genera Eukrohnia, Heterokrohnia, Bathyspadella).
Order APHRAGMOPHORA
Sub-Order CTENODONTINA
family Sagittidae (Genus Sagitta)
Family Pterosagittidae (Genus Pterosagitta)
Sub-Order FLABELLODONTINA
Family Krohnittidae (Genus Krohnitta)
This new classification for the Phylum Chaetognatha proposed by Tokioka (1965) has not been widely accepted and followed by other taxonomists. As Alvarino (1967) pointed out the highest rank, which might be used in grouping this Phylum, is that of Genus. The species included in each of the genera are separated by means of slight differences, in the position of various morphological structures, which are very closely related to each other. Therefore, further systematic division of this Phylum is not justified. So the Phylum Chaetognatha is divided into nine genera as detailed here: Genus Archeterokrohnia Casanova, 1986 So far about 100 species under the above nine genera are known from the different oceans. Though this is a small group, it occupies the second place in the order of abundance among the marine planktonic organisms, copepods being the fllst group. Further it plays a significant role in the food cycle. They occur in close association with copepods and an increase in the copepod population, is generally followed by proportionate increase in the chaetognath population.
Further, chaetognaths could be used as indicators of watermasses and their movements, because certain species are seen closely associated with particular type of watermass. This assoclation is useful in identifying a particular watermass in a region, where there are several bodies of water in which the salinity differences are not well marked. It has already been established along the Cali.{ornian coast (Alvarino, 1964). English Channel (Russel, 1935) and west coast of India (Srinivasan, 1976).
Historical Resume
i) Pre-1900
Prior to the year 1900, very little was known about the chaetognaths from the Indian seas and all the published reports prior to 1900 are about the chaetgnaths ofthe Atlantic and Pacific •Oceans. Though chaetognaths were fllst reported from Dutch coast in 1778 by Martin Slabber, brief description of the species of Sagitta was given by Quoy &Gaimard (1827) based on the sample.s collected from the Straits of Gibraltar. Then Charles Darwin (1884) reported the Sagitta species from the coasts of Brasil, Argentina and Chile. In 1895, Beraneck reported the chaetognaths from the Bay of Am~ine(pacific Ocean) including a new species (Sagitta bedotl). In 1897, Aida added there new species of chaetognaths (S. neglecta, S. regularis and Krohnitta pacifica) from the Misaki Harbour.
ii) 1901-1947=
Doncaster's (1903) report on the fauna and geography of the Maldives and Laccadives Archipelago is the fllst significant publication on the chaetognaths of the Indian Ocean. This report deSCribes 11 species including four new species (S. ferox, S. pulchra, S. robusta. S. septata). In 1906, Fowler while studying the. collections of the Siboga expedition in the Indian Ocean, reported 16 species and provided a complete distributional record of the then known 33 species.
Though several papers were published on the chaetognaths during the beginning of this country, the fllst comprehensive monograph on the morphology, distribution and bibliography of the Indian Ocean chaetognaths was published in 1911 by Ritter-Zahony. After this monograph, the contributions of Baldasseroni (1915) on the chaetognaths from the Bay of Bengal and Bwfield &Harvey (1926) on the 'Sea-Lark' expedition chaetognaths were the prominent ones. Burfield &Harvey (1926) discussed in detail about the horizontal and vertical distribution of the chaetognaths.
Schilp's (1941) report on the chaetognaths collected from the Indian Ocean during the 'Snellius' expedition is another notable contribution on the Indian Ocean chaetognaths. In this account he reported 19 species and discussed the horizontal and vertical distribution of these species.
The fmt report on the chaetognaths from the west coast was by Lele &Gae (1936) on the Bombay harbour chatognaths. Then a series of papers were published on the chaet~gnaths of Madras coast (John, 1933, 1937; Subramaniam, 1937, 1940)
iii) 1948-1990
There are not many publications on chatognaths of the Indian Seas during 40s and 50s of this century. The paper published during these two decades are by Varadarajan &Chacko (1943) and Menon (1946) on the chaetognaths from the Trivandrum coast; George (1949, 1952) on the Malabar coast chaetognaths; Chacko (1950) on the Krusadai Island chaetognaths; Rao (1958) and Rao and Ganapati (1958) on the Chaetognaths of the Andhra coast.
Tokioka (1962) gave a resume of the papers published on the Indian Ocean chaetognaths and the species reported from the Indian Ocean. Another important report on the Indian Ocean Chaetognaths is by Alvarino (1962) on the Monsoon expedition chaetognaths collected by RN ARGO during 1960-1961.
Nair (1967) studied ~e biomass of the chaetognaths from the Indian Ocean based on the samples collected during the International• Indian Ocean Expedition cruises from 1960-1965. Further she has pointed out the variability in the distrib.ution of chaetognaths in the Arabian Sea (1972). In 1973 Nair and Rao reported the occurrence of 19 species of chaetognaths from the nOE samples collected in the Arabian Sea. Further they have studied the chaetognaths from the Kavarathi Island (1973). In the same year they examined the chaetognaths from the upwelling areas of the Arabian Sea and reported 14 species. They stated that the population maxima of chaetognaths were found not adjacent to the centre of upwelling, but shifted to the fringe of enriched areas.
In 1977 Nair reported the chaetognaths from the Indian Ocean and she discussed the geographical distribution of different species found in the samples. Further in 1978, she studied the bathymetric distribution of 25 species of chaetognaths present in the samples collected during the cruises of U.S. ship Anton Bruun.
Silas and Srinivasan (1968. 1969, 1970) and Srinivasan (1972 a, b) have published a series of papers on the chaetognaths from the Arabian Sea.
In the Zoological Survey of India, studioes on chaetognaths from the Indian seas were initiated in 1974 by Srinivasan at the Marine Biological Station, Madras. He has published a series of papers on chaetognaths from the Madras coast and Ennore estuary (1975, 1976, 1977, 1979, 1980).
In 1979, Srinivasan also published a monograph on Chaetognatha incorporating the detailed descriptions of 22 species found in the Indian Seas, a key for the identification of the species, and the discussion on the possibility of using certain species as indicators of upwelling along the west coast of India He further studied the chaetogtiaths collected during the expedition cruises of INS DARSHAK (1987), INS KISTNA, RIMS INVESTIGATOR andoR. V. VITYAZ (1987); the third Indian Expedition to Antarctica (1988) and cruises 1-44 of FORV SAGAR SAMPADA (1989). In the last referred paper he pointed out that the density of chaetognath population was very rich between Cochin and Mangalore coasts and near the Kandla coast along the west coast of India. Along the east coast of India, the density of the chaetognath population was less than the west coast and certain areas between Madras and Andhra coasts and between Paradip and Bangladesh coast had higher density of chaetognath population than the remaining areas of the east coast.
Studies from Different Environs
In addition to the marine habitat, chaetognaths are also found in the estuarine habitat. Though there are many estuaries along the Indian coasts, chaetognaths are well known only from a few estuaries such .as Cochin backwaters (Nair, 1972, 1973, 1975; Srinivasan, 1972) and Mandovi¬Zuari estuary (Nair & Selvakumar, 1979) along the west coast and Ennore estuary (Srinivasan, 1972, 1977, 1980; Srinivasan &Raghunathan, 1978; Raghunathan &Srinivasan, 1983), Kakinada estuary (Rao, 1960) and Goavary estuary (Cahdramohan, 1963) along the east coast of India. Among the 100 species known from the World Oceans, only 9 species are so far known from the estuarine waters of India. Even among these nine species only two species, Sagitta belloti and S. entlata are commonly seen in estuaries.
Life cycle studies on certain chaetognath species in Cochin backwaters and .Ennore estuary (Nair, 1973; Srinivasan, 1980) revealed that the fully matured specimens of S, bedoti and S. enflata were absent in the estuarine waters, whereas the specimens of all the other sages were found. This may be due the possibility of migration of these adults towards the deeper lay~rs of the estuaries (David, 1955).
An interesting observation noted during these studies is the retarded growth in the total length of the specimens of S. bedoti and S. enflata (Srinivasan, 1972, 1977) from the Cochin backwaters and Ennore estuary.
Srinivasan and Krishnan (1985) studied the chaetognaths collected during the total solar eclipse from the Plankton samples collected in the coastal waters of Purl, Orissa, and observed the upward migration of chaetognaths along with the other planktonic organisms towards the surface waters. The number of chaetognaths found in the sample collected during the eclipse period was more than the number in the sample collected before and after the total solar eclipse.
Studies on chaetognaths of the Indian seas have revealed that the west coast has been well explored than the east coast. This may be due to the fact the Central Marine Fisheries Research Institute, stationed at Cochin has conducted several regular crusies along the west coast and collected plankton samples along the coast and around the Laccadives. Further the National Institute of Oceanography, stationed at Goa has also collected samples from the Arabian Sea. Along the east coast, only certain coastal areas around the Mandapam, Madms and Vishakhapatnam have been explored so far. The remaining coastal areas along the east coast, offshore waters and the seas around the Andaman &Nicobar Islands are yet to be explored.
Estimation of Taxa
So far about 100 specie of chaetognaths belonging to nine genera•are known from the World Oceans and less than 30 species are reported from the Indian Seas. This is probably due to the insufficient sampling from deeper waters of the Indian seas.
Genus-wise breakup of the Chaetognatha known from India seas: As this is a small Phylum with only 9 Genera and 1'00 species, generally the entire group is taken up as such for detailed taxonomic studies. Detailed biological studies have been carried out
Chiletognatha 557
on a few important species. Rao and Kelly (1962) studied the breeding habits of S. enflata in the Lawsoris Bay, Wal tair and concluded that this species breeds throughout the year, with several peaks of intensive breeding. Srinivasan (1972, 1977, 1980) examined the breeding habits and life cycle of S. bedoti and S. enflata from the samples collected in the Cochin backwaters and Ennore estuary and reported that both the species were continuous breeders. Nair (1973) also studied the breeding habits of S. enflata and S. bedoti from the Cochm backwaters and Nair et, ale (1975) analysed the bio-chemical composition of S. bedoti
Current Studies
In the Marine Biological Station, Zoological Survey of India, Madras, the taxonomy, ecology and distribution of chaetognaths collected during the regular cruises of the Departme~tal Vessel CHOTTA INVESTIGATOR and the sorted out chaetognath samples received from the Director, Central Marine Fisheries Research Institute, Cochin, collected during the regular cruises of FORV SAGAR SAMP ADA in Bay of Bengal and Arabian Sea are being studied.
Expertise India
In ZSI
M. Srinivasan, Zoological Survey of India, Southern Regional Station, 100, Santhome High Road, Madras 600 034
Elsewhere
Vijayalakshmi R. Nair, National Institute of Oceanography, Bombay.
Abroad
Sachiko Nagasawa, Ocean Research Institute, 1-15-1 Minamidai, Nakano-ku, 164 Japan. [Chaetognath natrial ecology, rhythmic activity, feeding].
Moriyuki Kotori, Holck. Centro Fish. Exp. Stn. Yoichi, Hokkaido, 046 Japan. [Biology and ecology ofParagitta elegans].
Angeles Alvarino, Southwest Fish. Center, P.O. Box 271, La Jolla, California 92038, U.S.A. [Systematics, anatomy, reproductioQ, feeding, zoogeography ecology, bethymetric distribution] .
George C. Grant, VIMS, Gloucester Point, Virginia 23062, U.S.A. [Distribution, taxonomy, ecology].
Jerry McLelland, Gulf coast Res. Lab, P.O. Box 7000, Ocean Springs, MS 39546, U.S.A. [Deep sea chaetognaths].
Thomas E. Bowman, Nation. Mus. of Nat. Hist. Smithonian Instit~tion, Washington D. C., 20560, U.S.A. [Spadellids].
Harding B. Michel, University of Miami, 4600 Tickenbacker Causeway, Miami, Florida 33149, U.S.A. [Ecology, Zoogeography and life histories].
Helga, Kapp, Zool. Inst Und Zool. Mus. Martin-Luther-King-Platz 3, 2000 Hamburg 13, Fed. Rep. Germany. [Systematics, zoogeography, vertical distribution and morphology].
Gerd Rehkamper, Anal. Inst. Univ. Kotn, Joseph-Stelzmann-Str. 95000 Koln 41, F.R.G. [Central nervous system, morphology].
Wilhelm Hagen, Inst.. f. Polarokologie Universitat Kiel, Olshausenstr. 40-60, 2300 Kiel I,
F.R.G. [Antarctic chaetognaths].
Ulrich Welsch, Anat. Anst. Univ. Munchen, Pettenkoferstrasse 11, 8000 Munchen 2 F.R.G. [Morphology, systematic position, skin, intestinal tract].
David Convay, Plymouth Mar. Lab. Prospect Place, The Hoe, Plymouth PLI 3HD, England. [Vertical distribution, diurnal and seasonal migration, biomass, production, mainly S. elegans].
Quentin Bone, Plymouth Mar. Lab. Citadel Hill, Plymouth PLI 2PB, England. [Muscle structure and function, structure of nervous system].
Kathleen C. Chidgey, Old Odiham Road, Alton, Hants GU34 2EJ England. [Taxonomy-and distribution] .
Conway Morris, Dep. of Earth Sciences, Univ. of Cambridge, CB2 3EQ Cambridge, England. [Metazoan relationships].
S. Van der Spoel, Inst. Tax. Zool. Univ. Arnst. P.O. Box 20125, 1000 HC Amsterdam, The Netherlands. [Systematics and biogeography].
A. C. Pierrot-Bulyts, Inst. Tax. Zoot. Univ. Arnst. P.O. Box 20125, 1000 HC Amsterdam, The Netherlands. [Systematics and biogeography].
Vidar Oresland, Dept. of Zoology, Univ. of Stockholm, S-106 91 Stockholm, Sweden. [Distribution, life cycle].
Sifford Pearre Jr. Dept. of Oceanography, Dalhousie University, Halifax, Nova Scotie, Canada b3H 4J1. [Vertical migration, feeding, trophic web relationships].
Jean Paul Casanova, Lab. de Biologie animale, Univ. de Provence, 13331 Marseille cedex 3 France. [Taxonomy, biology, zoogeography].
Michel Duvert, Lab. de Cyt. Univ. Bordeaux, Avenus des Facultes, 33405 Talence-Cedex, France. [Locomotion, muscular contraction].
Alia Kassatkina, Lab. Marine Biology, Zoological Institute, Leningrad 199 164, USSR. [Systematics, ecology, morphology, physiology and zoogeography].
Sigrid Ofner, Zoologie Inst. d. Univ. Althanstr, 14, 1090 Wien, Austria. [Taxonomy, morphology, distribution].
Selected References
Alvarino, A. 1967. The Chaetognatha of NAGA Expedition from South China Sea, Systematics. Naga Rep., 4 : 1-197.
Burfield, S. T. &Harvey, E. J. W. 1926. The Chaetognatha of the 'Sea Lark' Expetiditon. TraIlS. Linn. Soc. London, Sere 2, 19 : 93-119.
Fowler, G. H. 1906. The Chaetognatha from SIBOGA Expedition Sihoga Exped. Mongr., 21 : 1¬
86.
Ritter-Zahony, R. V. 1911. Revision der Chatognathen. DI. Suedpol. Exped. 1901-1903, 13 Zool. 5 : 1-71.
Schilp, H. 1941. Biological results of the 'Snellius' Expedititon. IX. The Chaetognatha of the Snellius Expedition. Temminckia, 6 : 1-99.
Srinivasan, M. 1979. Taxonomy, ecology of chaetognaths in relation to their role as indicator organisms of watermasses. 2001. Surv. India, Tech. Monogr.• 3 : 1-47.
