Feeding mechanisms and feeding strategies of Atlantic reef corals

Abstract

The feeding behaviour of 35 species of Atlantic reef corals was examined in the laboratory and in the field. Observations were made during the day and at night, using freshly hatched brine shrimp nauplii and finely ground, filtered fresh fish as food sources. Three feeding strategies were observed: Group I–feeding by tentacle capture only; Group II–feeding by entanglement with a mucus net or mucus filaments; Group III–feeding by a combination of tentacle capture and mucus filament entanglement. Group I included corals of the families Poritidae and Pocilloporidae which were normally expanded during both day and night. Group II included corals of the family Agaricidae which were normally expanded at night and contracted during the day. Group III included corals of the other families examined which, with the exception of Dendrogyra cylindrus, were normally expanded only at night. Feeding responses were elicited by both chemical and tactile stimuli. A preparatory feeding posture was assumed in response to chemical stimuli and consisted of horizontal positioning of the tentacles, elevation of the oral disk to form a cone‐like mouth, a wide mouth opening and secretion of mucus by the epidermis of the oral disk. Following the assumption of the preparatory feeding posture, food capture and ingestive movements were elicited by tactile stimuli. However, food capture and ingestive movements were also elicited by chemical stimuli alone in those species which were normally contracted during the day. While expanded corals captured food with their tentacles or with mucus filaments, contracted corals were able to feed by capturing fine particulate matter with mucus filaments only and thus acted as suspension feeders. By a combination of feeding strategies, reef corals were able to feed both day and night and a wide range of potential food ranging from fine particulate matter to large zooplankton was available to them.

Feeding behaviour and feeding ecology of the Octocorallia (Coelenterata: Anthozoa)

“…In contrast to other Anthoza (Lewis & Price, 1975;Lewis, 1978), no mucus nets or strands were observed in feeding polyps of any of the alcyonacean species examined. However, mucus is produced, often in copious amounts, by a number of species.…”

Feeding behaviour and feeding ecology of the Octocorallia (Coelenterata: Anthozoa)

“…In contrast to other Anthoza (Lewis & Price, 1975;Lewis, 1978), no mucus nets or strands were observed in feeding polyps of any of the alcyonacean species examined. However, mucus is produced, often in copious amounts, by a number of species.…”

Direct Visualization of Mucus Production by the Cold-Water Coral Lophelia pertusa with Digital Holographic Microscopy

“…salina in mucus strands, confirming similar observations by Purser et al [ 23 ]. Furthermore, Fig 5A clearly shows how the mucus strings originate at the mouth of the polyps and are stretched and aligned due to the water flow conditions within the chamber, reinforcing the more general observation for scleractinian corals that mucus is released from the epidermis of the oral disk as polyps initiate their preparatory feeding posture [ 46 ]. We also observed distinctive mucus string balls in association with the addition of A .…”

Patterns of ciliary currents in Atlantic reef corals and their functional significance

“…As has been previously reported (Price, 1973;Lewis & Price, 1975) polyps of the two species of Acroporjdae, Acropora palmata and Acropora cervicornis, were seldom observed fully expanded. In partially expanded polyps ciliary currents were directed away from the mouth, down the stalk but up the cylindrical corallites.…”

Feeding behaviour and feeding ecology of the Octocorallia (Coelenterata: Anthozoa)

“…In contrast to other Anthoza (Lewis & Price, 1975;Lewis, 1978), no mucus nets or strands were observed in feeding polyps of any of the alcyonacean species examined. However, mucus is produced, often in copious amounts, by a number of species.…”

Direct Visualization of Mucus Production by the Cold-Water Coral Lophelia pertusa with Digital Holographic Microscopy

“…salina in mucus strands, confirming similar observations by Purser et al [ 23 ]. Furthermore, Fig 5A clearly shows how the mucus strings originate at the mouth of the polyps and are stretched and aligned due to the water flow conditions within the chamber, reinforcing the more general observation for scleractinian corals that mucus is released from the epidermis of the oral disk as polyps initiate their preparatory feeding posture [ 46 ]. We also observed distinctive mucus string balls in association with the addition of A .…”

Patterns of ciliary currents in Atlantic reef corals and their functional significance

“…As has been previously reported (Price, 1973;Lewis & Price, 1975) polyps of the two species of Acroporjdae, Acropora palmata and Acropora cervicornis, were seldom observed fully expanded. In partially expanded polyps ciliary currents were directed away from the mouth, down the stalk but up the cylindrical corallites.…”

Feeding behaviour and feeding ecology of the Octocorallia (Coelenterata: Anthozoa)

“…In contrast to other Anthoza (Lewis & Price, 1975;Lewis, 1978), no mucus nets or strands were observed in feeding polyps of any of the alcyonacean species examined. However, mucus is produced, often in copious amounts, by a number of species.…”

Direct Visualization of Mucus Production by the Cold-Water Coral Lophelia pertusa with Digital Holographic Microscopy

“…salina in mucus strands, confirming similar observations by Purser et al [ 23 ]. Furthermore, Fig 5A clearly shows how the mucus strings originate at the mouth of the polyps and are stretched and aligned due to the water flow conditions within the chamber, reinforcing the more general observation for scleractinian corals that mucus is released from the epidermis of the oral disk as polyps initiate their preparatory feeding posture [ 46 ]. We also observed distinctive mucus string balls in association with the addition of A .…”

Patterns of ciliary currents in Atlantic reef corals and their functional significance

“…As has been previously reported (Price, 1973;Lewis & Price, 1975) polyps of the two species of Acroporjdae, Acropora palmata and Acropora cervicornis, were seldom observed fully expanded. In partially expanded polyps ciliary currents were directed away from the mouth, down the stalk but up the cylindrical corallites.…”