Advertisement

Zoomorphology

, Volume 107, Issue 6, pp 319–337 | Cite as

Structure and function of the prehensile tentilla of Euplokamis (Ctenophora, Cydippida)

  • G. O. Mackie
  • C. E. Mills
  • C. L. Singla
Article

Summary

Euplokamis has coiled tentilla on its tentacles, which can be discharged, flicking out at high velocity, when triggered by contact with prey. The tentillum adheres to prey by means of numerous colloblasts. Discharge, which takes 40–60 ms, is accomplished by contraction of striated muscles, found only in this genus among the Ctenophora. Restoration of the coiled state is attributable to passive, elastic components of the mesogloea. Rows of “boxes” (fluid-filled compartments) along the sides of the tentillum appear to stiffen the structure so that it does not collapse, kink or buckle during discharge. Smooth muscle fibres present in the tentillum may help pull the tentillum tight after prey have been captured.

In addition to the rapid discharge response, the tentillum can perform slower, spontaneous, rhythmic movements which, it is suggested, resemble the wriggling of a plank-tonic worm, enabling the tentillum to function as a lure. These movements appear to be executed by contraction of two sets of myofilament-packed cells which differ in several important respects from conventional smooth muscle. They belong to a novel and distinct cytological subset (“inner-ring cells”), other members of which are packed with microtubules and seem to be involved in secondary structuring of the collagenous component of the mesogloea.

Study of tentilla in different stages of development shows that the striated muscle fibres, originally nucleated, become enucleate as they differentiate and that the colloblasts form in association with accessory cells, as proposed by K. C. Schneider and G. Benwitz. The refractive granules which adhere to the outside of all mature colloblasts derive from these accessory cells. The colloblast nucleus undergoes changes during development suggestive of progressive loss of its role in transcription and protein synthesis, but it remains intact, contrary to statements in the literature.

The tentillum of Euplokamis can be regarded as a true food-capturing organ and it is probably the most highly developed organ in the phylum.

Keywords

Striate Muscle Smooth Muscle Muscle Fibre Protein Synthesis Secondary Structure 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Bargmann W, Jacob K, Rast A (1972) Über Tentakel und Colloblasten der Ctenophore Pleurobrachia pileus. Z Zellforsch 123:121–152Google Scholar
  2. Benwitz G (1978) Elektronenmikroskopische Untersuchung der Colloblasten-Entwicklung bei der Ctenophore Pleurobrachia pileus (Tentaculifera, Cydippea). Zoomorphology 89:257–278Google Scholar
  3. Chun C (1880) Die Ctenophoren des Golfes von Neapel. Fauna und Flora des Golfes von Neapel 1:311Google Scholar
  4. Franc J-M (1985) La Mésoglée des Cténaires: Approches ultrastructurale, biochimique et métabolique. Thesis, Université Claude Bernard (Lyon 1), pp 1–226Google Scholar
  5. Franc J-M (1978) Organization and function of ctenophore colloblasts: an ultrastructural study. Biol Bull 155:527–541Google Scholar
  6. Franc S, Franc J-M, Garrone R (1976) Fine structure and cellular origin of collagenous matrices in primitive animals: Porifera, Cnidaria and Ctenophora. In: Robert L (ed) Frontiers in matrix biology, vol 3. Karger, Basle, pp 143–156Google Scholar
  7. Gilbert SP, Allen RD, Sloboda RD (1985) Translocation of vesicles from squid axoplasm on flagellar microtubules. Nature 315:245–248Google Scholar
  8. Hernandez-Nicaise M-L (1968) Specialized connexions between nerve cells and mesenchymal cells in ctenophores. Nature 217:1075–1076Google Scholar
  9. Hernandez-Nicaise M-L (1973a) Le systéme nerveux des Cténaires: I. Structure et ultrastructure des réseaux epithéliaux. Z Zellforsch 137:223–250Google Scholar
  10. Hernandez-Nicaise M-L (1973b) Le systéme nerveux des Cténaires: II. Les éléments nerveux intra-mésogléens des béroidés et des cydippidés. Z Zellforsch 143:117–133Google Scholar
  11. Hernandez-Nicaise M-L (1973c) The nervous system of ctenophores: III. Ultrastructure of synapses. J Neurocytol 2:249–263Google Scholar
  12. Hernandez-Nicaise M-L (1974a) Ultrastructural evidence for a sensorimotor neuron in Ctenophora. Tissue Cell 6:43–47Google Scholar
  13. Hernandez-Nicaise M-L (1974b) Systéme nerveux et intégration chez les Cténaires: études ultrastructurale et comportementale. Thesis, Université Claude Bernard (Lyon 1), pp 1–200Google Scholar
  14. Hernandez-Nicaise M-L, Bilbaut A, Malaval L, Nicaise G (1982) Isolation of functional giant smooth muscle cells from an invertebrate: structural features of relaxed and contracted fibres. Proc Natl Acad Sci USA 79:1884–1888Google Scholar
  15. Horridge GA (1965) Non-motile cilia and neuromuscular junctions in a ctenophore independent effector organ. Proc R Soc [B] 162:333–350Google Scholar
  16. Hovasse R, de Puytorac P (1962) Contributions á la connaissance du colloblaste, grâce á la microscopie electronique. CR Acad Sci (Paris) [D] 255:3223–3225Google Scholar
  17. Hoyle G (1983) Muscles and their neural control. Wiley, New York, pp 1–689Google Scholar
  18. Hyman LH (1940) The invertebrates: Protozoa through Ctenophora. McGraw-Hill, New York, pp 726Google Scholar
  19. Komai T (1922) Studies on two aberrant ctenophores, Coeloplana and Gastrodes. Published by the author, Kyoto, pp 102Google Scholar
  20. Lendenfeld R von (1885) Über Coelenteraten der Südsee: VI. Neis cordigera Lesson, eine australische Beroide. Z Wiss Zool 41:673–682Google Scholar
  21. Mackie GO (1985) Midwater macroplankton of British Columbia studied by submersible PISCES: IV. J Plankton Res 7:753–777Google Scholar
  22. Mackie GO, Mills CE (1983) Use of Pisces IV submersible for zooplankton studies on coastal waters of British Columbia. Can J Fisheries Aquat Sci 40:763–776Google Scholar
  23. Purcell JE (1980) Influence of siphonophore behavior upon their natural diets: evidence for aggressive mimicry. Science 209:1045–1047Google Scholar
  24. Schneider KC (1902) Lehrbuch der vergleichenden Histologie der Tiere. Fischer, Jena, pp 1–988Google Scholar
  25. Storch V, Lehnert-Moritz K (1974) Zur Entwicklung der Kolloblasten von Pleurobrachia pileus (Ctenophora). Mar Biol 28:215–219Google Scholar
  26. Tamm SL (1982) Chapter 7, Ctenophora. In: Shelton GAB (ed) Electrical conduction and behaviour in “simple” invertebrates. Clarendon, Oxford, pp 266–358Google Scholar
  27. Wainwright SA, Biggs WD, Currey JD, Gosline JM (1976) Mechanical design in organisms. Arnold, London, pp 1–423Google Scholar
  28. Weill R (1935) Structure, origine et interprétation cytologique des colloblastes de Lampetia pancerina Chun (Cténophores). CR Acad Sci (Paris) [D] 200:1628–1630Google Scholar

Copyright information

© Springer-Verlag 1988

Authors and Affiliations

  • G. O. Mackie
    • 1
  • C. E. Mills
    • 2
  • C. L. Singla
    • 1
  1. 1.Department of BiologyUniversity of VictoriaVictoriaCanada
  2. 2.Friday Harbor LaboratoriesUniversity of WashingtonFriday HarborUSA

Personalised recommendations