Scientia Marina, Vol 71, No 2 (2007)

Feeding behaviour of the hydromedusa Aequorea vitrina

Hans Ulrik RiisgÅrd
Marine Biological Research Centre, University of Southern Denmark, Hindsholmvej, Denmark


The prey-capture mechanism of the hydromedusa Aequorea vitrina was studied by means of laboratory video-microscope observations. In stagnant water A. vitrina remains stationary with its very long (about 4x bell diameter) marginal tentacles motionless hanging down in the water, ready for ambush capture of prey organisms that collide with the tentacles. A. vitrina was found to be efficient at capturing brine shrimps (Artemia salina), less efficient at capturing rotifers (Brachionus plicatilis), and very inefficient at capturing copepods (Acartia tonsa). The initial hauling up of an extended marginal tentacle with an adhering prey is fast (>10 mm s-1). Both the bell margin and the mouth move towards each other so that the captured prey can be transferred from the tentacle to the elongated mouth-lips to be further transported into the mouth and stomach. It takes about 20 s from when an Artemia prey organism encounters a tentacle until it is transferred to the mouth-lips. The subsequent digestion in the stomach takes about 30 min. When A. vitrina encounters a jellyfish-prey (a small medusa of Aurelia aurita), it starts to swim in order to adhere the relatively big prey to its mouth-lips. Then A. vitrina opens its mouth wide to swallow the captured medusa, a process which takes about 15 to 20 min. The subsequent digestion takes 2 to 3 h. Field observations of undisturbed A. vitrina made by snorkelling in the Limfjord (Denmark) revealed that the feeding behaviour was similar to that observed in the laboratory in stagnant water. It is concluded that A. vitrina is an ambush-predator, and not a cruising-predatory medusa as previously suggested.


Aequora vitrina; prey capture mechanism; video-microscope observations

Full Text:



Akaike, H. – 1973. Information theory and an extension of the maximum likelihood principle. In: B.N. Petrov and F. Csaki (eds.), Second international symposium on information theory, pp. 267-281. Akademiai Kiado, Budapest.

Akaike, H. – 1981. Likelihood of a model and information criteria. J. Econometrics, 16: 3-14 doi:10.1016/0304-4076(81)90071-3

Akaike, H. – 1983. Information measures and model selection. B. Int. Stat. Inst., 44: 277-291.

Buckland, S.T., K.P. Burnham and N.H. Augustin. – 1997. Model selection: an integral part of inference. Biometrics, 53: 603-618. doi:10.2307/2533961

Burnham, K.P. and D.R. Anderson. – 2002. Model selection and multimodel inference: a practical information-theoretic approach, 2nd edn. Springer, New York.

Cannicci, S., J. Paula and M. Vannini. – 1999. Activity pattern and spatial strategy in Pachygrapsus marmoratus (Decapoda: Grapsidae) from Mediterranean and Atlantic shores. Mar. Biol., 133: 429-435. doi:10.1007/s002270050481

Cannicci, S., M. Gomei, B. Boddi and M. Vannini. – 2002. Feeding habits and natural diet of the intertidal crab Pachygrapsus marmoratus: Opportunistic browser or selective feeder? Estuar. Coast. Shelf Sci., 54: 983-1001. doi:10.1006/ecss.2001.0869

Ebert, T.A. and M.P. Russell. – 1994. Allometry and Model II nonlinear regression. J. Theor. Biol., 168: 367-372. doi:10.1006/jtbi.1994.1116

Efron, B. and R.J. Tibshirani. – 1993. An introduction to the bootstrap. Chapman and Hall, New-York.

Flores, A. and J. Paula. – 2001. Intertidal distribution and species composition of brachyuran crabs at two rocky shores in Central Portugal. Hydrobiologia, 449: 171-177. doi:10.1023/A:1017573927565

Flores, A. and J. Paula. – 2002. Population dynamics of the shore crab Pachygrapsus marmoratus (Brachyura: Grapsidae) in the central Portuguese coast. J. Mar. Biol. Ass. U.K., 82: 229-241. doi:10.1017/S0025315402005404

Flores, A. and M.L. Negreiros-Fransozo. – 1999. Allometry of the socondary sexual characters of the shore crab Pachygrapsus transversus (Gibbes, 1850) (Brachyoura, Grapsidae). Crustaceana, 72: 1051-1066. doi:10.1163/156854099504013

Hall, N.G., K.D. Smith, S. de Lestang and I.C. Potter. – 2006. Does the largest chela of the males of three crab species undergo an allometric change that can be used to determine morphometric maturity? ICES J. Mar. Sci., 63: 140-150. doi:10.1016/j.icesjms.2005.07.007

Hartnoll, R.G. – 1963. The biology of Manx spider crabs. Proc. Zool. Soc. London, 141: 423-496.

Hartnoll, R.G. – 1983. Strategies of Crustacean Growth. Aus. Mus. Syd. Mem., 18: 121-131.

Hartnoll, R.G. – 1985. Growth, sexual maturity and reproductive output. In: A.M. Wenner (ed.), Crustacean issues 3, Factors in adult growth. Balkema, Rotterdam/Boston.

Hurvich, C.M and C.L. Tsai. – 1989. Regression and time series model selection in small samples. Biometrika, 76: 297-307. doi:10.1093/biomet/76.2.297

Huxley, J.S. – 1932. Problems of relative growth. Methuen, London.

Ingle, R.W. – 1980. British crabs. British Museum (Natural History), Oxford University Press, London.

Jolicoeur, P. – 1990. Bivariate allometry: interval estimation of the slopes of the ordinary and standardized major axes and structural relationship. J. Theor. Biol., 144: 275-285. doi:10.1016/S0022-5193(05)80326-1

Katsanevakis, S. – 2006. Modelling fish growth: model selection, multi-model inference and model selection uncertainty. Fish. Res., 81: 229-235. doi:10.1016/j.fishres.2006.07.002

Katsanevakis, S., M. Thessalou-Legaki, C. Karlou-Riga, E. Lefkaditou, E. Dimitriou and G. Verriopoulos. – 2007a. Information-theory approach to allometric growth of marine organisms. Mar. Biol., 151: 949-959. doi:10.1007/s00227-006-0529-4

Katsanevakis, S., J. Xanthopoulos, N. Protopapas and G.Verriopoulos. – 2007b. Oxygen consumption of the semi-terrestrial crab Pachygrapsus marmoratus in relation to body mass and temperature: an information theory approach. Mar. Biol., 151: 343-352. doi:10.1007/s00227-006-0485-z

McQuarrie, A.D.R. and C.L. Tsai. – 1998. Regression and time series model selection. World Scientific Publishing Company, Singapore.

Olmsted, J.M.D. and J.P. Baumberger. – 1923. A comparison of the form of three species of grapsoid crabs. J. Morphol., 38: 279-294. doi:10.1002/jmor.1050380203

Sainte-Marie, B. and G.A. Lovrich. – 1994. Delivery and storage of sperm at first mating of female Chionoecetes opilio (Brachyoura: Majidae) in relation to size and morphometric maturity of male parent. J. Crust. Biol., 14: 508-521. doi:10.2307/1548997

Shea, E.K. and M. Vecchione. – 2002. Quantification of ontogenetic discontinuities in three species of oegopsid squids using model II piecewise linear regression. Mar. Biol., 140: 971-979. doi:10.1007/s00227-001-0772-7

Somerton, D.A. – 1981. Regional variation in the size of maturity of two species of tanner crab (Chionoecetes bairdi and C. opilio) in the eastern Bering Sea, and its use in defining management subareas. Can. J. Fish. Aquat. Sci., 38: 163-174. doi:10.1139/f81-022

Somerton, D.A. – 1983. The size at sexual maturity of the blue king crab, Paralithodes platypus, in Alaska. Fish. Bull., 81: 621-628.

Tsuchida, S. and S. Watanabe. – 1997. Growth and reproduction of the grapsid crab Plagusia dentipes (Decapoda: Brachyoura). J. Crust. Biol., 17: 90-97. doi:10.2307/1549466

Vernet-Cornubert, C. – 1958. Recherches sur la sexualité du crab Pachygrapsus marmoratus (Fabricius). Arch. Zool. Exp. Gén., 96: 104-276.

Copyright (c) 2007 Consejo Superior de Investigaciones Científicas (CSIC)

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Contact us

Technical support