Zooxanthellae provide their coral hosts with a proportion of their
required energy (Barnes & Hughes, 1999). As well as gaining energy
from their symbiotic zooxanthellae, many corals feed at night by
consuming zooplankton prey (Barnes 1987, Sebens et al. 1996,
Ferrier-Pages et al. 2003). By extending their tentacles equipped with
stinging nematocyst cells, corals are able to capture the zooplankton in
the water column. The trapped prey is then transported to the centre of
the polyps' oral disk and ingested through the gastrovascular cavity.
In addition to capturing zooplankton, many corals also collect fine
particles in mucus film or strands covering their surface. The mucus and
trapped particles are then transported to the mouth by the cilia at the
coral tissue surface (Barnes & Hughes, 1999). In this video, corals
are using their nematocyst-laden tentacles to capture food particles
from the water column, drawing them towards the mouth for ingestion.
Credits
Cinematography: Neilan Kuntz
Edited by: Neilan Kuntz
Written by: Neilan Kuntz
Location: Bocas del Toro, Panama (2003)
Barnes, R. (1987) Invertebrate Zoology. 5th Edition. Orlando, FL: Harcourt Brace Jovanovich, Inc. pp. 149-163.
Barnes, R., R. Hughes (1999). An Introduction to Marine Ecology. 3rd Edition. Malden, MA: Blackwell Science, Inc. pp. 117-141.
Ferrier-Pagés, J. Witting, E. Tambutté, K.P. Sebens (2003) Effect of natural zooplankton feeding on the tissue and skeletal growth of the scleractinian coral Stylophora pistillata. Coral Reefs 22(3): 229-240.
Seben KP, K.S. Vandersall, L.A. Savina, K.R. Graham (1996) Zooplankton capture by two scleractinian corals, Madracis mirabilis and Montastrea cavernosa, in a field closure. Marine Biology 127(2): 303-317
Hydrocorals
Hydrocorals are not true corals, but are member of the class
Hydrozoa. Like their close relatives, hydrocorals are also equipped with
stinging nematocyst cells that release a virulent toxin when they come
in contact with another organism (Wittle et al., 1974). Competitive,
hydrocorals in the genus Millepora are often conspicuous and form
spatially dominant colonies in reefs (Witman, 1988). The following
footage demonstrate the competitive ability of a Millepora spp. colony
that has pierced the tissues of an adjacent soft coral.
Credits
Cinematography:
Neilan Kuntz
Edited by: Neilan Kuntz
Written by: Dr. Olga Pantos
Location:
Bocas del Toro, Panama (2004)
Witman, J.D. (1992) Physical
disturbances and community structure of exposed and protected reefs: a
case study from St. John, US Virgin Islands. American Zoologist 32:
641-654.
Wittle, L.W., E.D. Tscura et al. (1974) Stinging coral
(Millepora tenera) toxin: a comparison of crude extracts with isolated
nematocyst extracts. Toxicon 12(5): 481-486.
Corals fight for space on reefs. One type of aggressive behavior
involves the use of their sweeper tentacles and extruded digestive
filaments (Lang and Chornesky, 1990). Typically, upon contact an
aggressive coral will attack its neighbor resulting in the mortality of
the damaged tissue (Lang, 1973). The following sequence illustrates two
adjacent corals of the same species (distinguished only by their
pigmentation) that have a defined boundary at the interface of the
colonies where the polyps have died. It appears that corals of the same
species but of different colonies can be antagonistic to one another.
Credits
Cinematography:
Dr. Forest Rohwer
Edited by: Neilan Kuntz
Written by: Neilan
Kuntz
Location: Borneo, Malaysia (Sipadan) (2002)
Lang, J. and
E.A. Chornesky (1990) Competition Between Scleractinian Reef Coralsâ€A
review of mechanisms and effects, pp. 209-257. In:Z. Dibinsky (ed.),
Coral Reefs’ Ecosystems of the World. V. 25. New York: Elsevier.
Lang,
J. (1973) Interspecific Aggression by Scleractinian corals. 2: Why the
Race is Not Always to the Swift. Bulletin of Marine Science 23: 260-279.
Sea anemones, along with hydrozoans and jellyfish belong to the
phylum Cnideria, which is characterized by specialized stinging cells
called nematocysts. Nematocysts are used to hunt and defend against
predators* (Kass-Simon and Scappaticci, 2002). In addition to the
nematocysts found within the tentacles, some sea anemones have
specialized fighting tentacles or acrorhagi. After making contact with
another organism, these hollow structures expand and adhere to the other
organism. The nematocysts continue to fire resulting in the process
referred to as "peeling" where the tissues beneath the acrorhagi to
become necrotic and peel off (Bigger 1988). In the following clip, a
sea anemone has attached itself between two coral colonies and has
killed all of the coral tissue within its reach. *Refer to Net Trapping for
hunting
Credits
Cinematography:
Neilan Kuntz
Edited by: Neilan Kuntz
Written by: Dr. Olga Pantos
Location:
Bocas del Toro, Panama (2003)
Bigger, C.H. (1988) The role of
nematocysts in anthozoan aggression. In: the biology of nematocysts.
Edited by D.A. Hessinger and H.M. Lenhoff. Academic Press, Inc., San
Diego. Pp. 295-308.
Kass-Simon, G. and Scappaticci, A.A. (2002)
The behavioral and developmental physiology of nematocysts. Canadian
Journal of Zoology 80: 1772-1794.
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