Ostreobium spp., O. quekettii A ubiquitous boring algae that lives in the skeleton of stony corals. Once a coral is stressed, it may become problematic by increasing its growth, exacerbating recession, and allowing for other disease and necrosis to occur. (Le Campion-Alsumard et al. 1995). Ostreobium develops when the growth conditions for the coral are optimal, and bands of these endolithic algae may be comprised of several genera of algae (Hutchings 1986).

Oscillatoria spp. Blue-green algae (cyanobacteria) which encroach upon the surface of coral, feeding off the mucus as a nutritive substrate. It is thought that the products of their metabolism may be toxic to coral tissue. O. submembranacea may cause or be a component of band-type necrosis in stressed or injured corals The growth of this reddish filamentous algae smothers corals, causing their death.

Plocamium hamatum A red algae that frequently grows on soft corals, especially Sinularia. It releases a terpene, known as chloromertensine, that can kill Sinularia spp.

Cochlodinium catenatum dinoflagellate reported to cause coral mortality, bleaching, and tissue sloughing. Tubastraea sp. and Pocillopora sp. most affected.

Gonyaulax monilata toxic dinoflagellates that can cause coral mortality.

Entophyzalis deusta Boring cyanobacteria that can damage similar to Ostreobium.

Heyella spp.

Matigocoleus testarum.

Ascidians: Many secrete toxic substances which can retard coral growth or cause necrosis and death.

Barnacles: Certain species are predatory and parasitic.

Pyrogama monticulariae A true parasite of stony corals dependent on coral for food and habitat. Actively controls calcification, tissue growth and nematocysts. Eats coral tissue. Most other barnacles of the family Pyrgomatidae are merely commensals.

Astrothoracia spp. fairly common parasites of gorgonians, especially those from deep water.

Certain species are parasitic and predatory. Some may form galls in coral tissue and may or may not be true parasites like the gall crabs. Many are merely commensal, living on coral mucus and associated flora and fauna. As such, they may be performing a cleaning function.

Hyperia galba amphipod predatory to coral tissue

Paramphiascopsis sp. parasitizes from a pocket formed in the tissue of gorgonians

Paramolgus antillianus associated with Ricordea florida

Acontiophorus bracatus ectoparasite of gorgonians, Leptogorgia, Eunicella and Paraerythropodium spp.

Asteropontius corallophilus parasite of Pocillopora, Montipora, Stylophora and Porites spp.

Asteropontius longipalpus associated with Ricordea florida

Asterocheres scutatus parasite of Rhodactis rhodostoma

Lichomologus spp. 6 species parasitic to octocorals, 3 species to fungiids, 7species to octocorals and stony corals, 5 species withPalythoa spp., 2 species with Rhodactis spp., 2 species with Psammocora spp. , 10 species to stony corals.

Acanthomolgus spp. 4 species parasitic to Atlantic gorgonians, often species specific

Psuedanthessiids spp. true parasites for all species in this genus

Rynchomolgids spp. true parasites for all species in this genus

Notodelphyids spp. some true parasites of octocorals, Paraerythropodium sp.

Xarfia spp. copepods with worm-like bodies and reduced legs that are parasitic and live inside coral polyps.

Crabs:

Caphrinae spp. portunid crabs associated with Xenia spp., and other Alcyonarians

Caphyra laevis preys on Xenia elongata

Caphyra polita associated with Red Sea (?) Xenia, Heteroxenia, Cespitularia spp.

Callinus spp. live under corals and feed on coral polyps

Trizopagurus spp. live under corals and feed on coral polyps

Chryptocherius spp. Dwells in a hole in massive corals. Larvae settle on the coral, killing polyps in that local area. The polyps do not grow back, and the hole deepens as the coral grows, creating this crab's home.

 

Echinoderms:

Many sea stars are corallivorous. Many are highly mixotrophic, consuming what is available to them, including coral polyps.. There are a number of sea urchins, including club urchins, pencil urchins, and others which may be corallivorous or inadvertent coral grazers. Many may feed on juvenile corals, including Diadema spp. Others may not just graze the coral, but may erode the surface to create a shallow depression in which they choose to dwell. A review of the echinoderms can be found in Gordon (1995).

Echinometra mathaei burrowing urchin that is involved with in some extensive boring action responsible for the detachment of coral heads.

Heterocen trotus pencil urchin that bores into dead and occasionally live coral skeletons and rock.

Culcita novaeguinae asteroid sea star that feeds on juvenile Acropora and Pocillopora spp., among others. A significant corallivore, perhaps second only to Acanthaster planci

Diadema antillarum can prey on juvenile and adult stony corals

Eucidaris sp. grazes Pocillopora sp. and others (?)

Four primary threats to corals occur exist with coral-associated gastropods and bivalve mollusks: one groups has members which are predatory or parasitic, a second group bores into living and/or dead corals, the third group lives or attaches to the exterior surface of corals, and the fourth group acts as substrate for corals. Some, such as members of Magilidae (the coral snails), live on corals exclusively. A reference is best consulted to discover the feeding habits of any unknown gastropod. The prosobranch gastropods in the families Architectonicidae (sundials), Epittoniidae (wentletraps), Ovulidae (cowries), Muricidae (murex), and Coralliophilidae (a name which literally translates to "coral lovers" and consists of the rapa and coral snails) are the most likely to prey on corals. There are some opisthobranch gastropods, notably Phestilla spp., that are also corallivorous. Nudibranchs of the genera Dendronotus, Phyllidia, Tritonia and several others may be exclusively corallivorous.

Nudibranchs: Some nudibranchs and sea slugs are coral predators. Some family members prey on soft corals, stony corals, gorgonians, and hydrocorals. A reveiew of nudibranchs can be found in Debelius (1996).

Armina spp. preys on corals

Tritonia spp. preys on octocorals

T. hombergi Alcyonium digitatum

T. bayeri Briareum abestinum, Psuedopterogorgia spp.

T. pickensii Gorgonia spp.

Phestilla spp. preys on stony corals

P. melanobrachia Tubastraea aurea, Dendrophyllia spp.

P. longicirra Sarchophyton trocheliophorum - This species stores soft coral toxins in its cerata

Phyllidia spp. some species prey on soft corals, including Sarcophyton spp. - may store toxins in cerata

P. bourgini parasitic nudibranch to Acropora spp., Millepora sp.

Aplacophora sp. predatory to octocorals

Neomeniomorpha spp. mainly predatory to octcorals, gorgonians

Pleuroleura spp. some species predatory to stoloniferans

P. striata Clavularia hamra

Aeolis sp. apparently specific to Xenia and Heteroxenia sp. in the Red Sea (Gohar 1940)

Cowries:

Some of the ovulids, or cowries, are coral predators. They are often highly species specific.

Calpurnus spp. soft coral predators

C. lacteus soft corals

C.verrucosus soft corals

Ovula ovum egg cowry - preys on Sarcophyton spp. and others (?), avoids toxins by converting sarcophytoxide to a less toxic form in the stomach.

S. patula predator of tissues of Eunicella spp. (for pigment?).

Cyphoma spp. gorgonian feeders. Three species associated with Psuedopterogorgia, Plexaura, Plexaurella and other gorgonians,. They have brightly colored mantles covering their shell which aids in camouflaging them against their host. They deposit their eggs on the gorgonians surface.

C. gibbosum Plexuara homomalla, Gorgonia spp., Briareum spp., others gorgonians, soft corals detoxifies the harmful metabolites like O. ovum.

C. signatum gorgonians

Jenneria pustulata stony corals, especially Pocillopora sp.

Pedicularia spp. Sylaster spp., gorgonians, stony corals

Members of the superfamily Muricidae, including members of the families Drupidae and Coralliophilidae, are among the most well known coral predators.

Drupa spp. some family members may be coral predators

Drupella cornus Porites spp., Stylophora spp., Seriatopora spp., branching corals, Montipora spp., Acropora spp., Pocillopora spp., Echinopora spp., Porites compressa. This species rasps off coral tissue with a specialized radula. Considered a major corallivore and predator, possibly second only to Acanthaster planki.

D. rugosa stony corals, preys on species normally not preferred. Prefers Acropora spp and pocilloporids.

Latiaxis spp. feeds on gorgonians

Quoyola spp. This genus has a limpet-like shell and feeds externally on stony corals. These snails are sessile, dissolving coral aragonite with acidic secretions from their foot with calcium carbonate which is then added as a scar-like attachment back to the corallum surface as they feed. They never leave their host coral, and probably do not account as a true predator as they maintain the integrity of the host colony, unless many are present. In such cases, loss may be too great for recovery.

Q. madreporarum Montipora spp., pocilloporids

Q. monodonta Porites spp., pocilloporids, Porites nigrescens

Magilopsis spp. ovoid snails that bore holes into coral tissue, dwelling

Leptoconchus sp. in the skeleton and living in tubes connected to the surface, common to Acropora, Goniastrea and Millepora spp., but have been found in over 50 species, indicating a wide range of hosts.

Reliquiecava spp. Boring snails, similar in action to Leptoconchus spp. Found associated with stony corals, four reported species in New Guinea (Massin 1988)

Magilus spp. snails which bore into corals, uncoiling and then living inside them. Generally more species specific than Leptoconchus spp.

M. antiquus Has been found associated with four stony corals.

Coralliophila spp. use saliva enzymes to externally dissolve coral tissue and suck it up. These snails do not rasp tissue as they lack a radula. Coral tissue rarely recovers as algae generally colonizes the corallum surface first.

C. abbreviata Montastrea annularis, Acropora palmata, Diploria clivosa, Favia fragum

C. caribea gorgonians, A. palmata, D. clivosa

C. erosa Acropora spp., Montipora spp.

C. sugimotonis Palythoa spp.

C. violacea Porites spp., pocilloporids - these snails are sessile, and they stay on their host coral, producing a thin aragonite attachment layer from which they move and feed on nearby tissue.

C. costularis Porites spp., pocilloporids, Goniopora spp. - moves from coral to coral, staying near the inner branches for protection as it moves outward eating living tissue.

Cronia margariticola preys on many species of stony corals.

Parviturboides interruptus dominant mollusk on Oculina sp.

Rapa rapa snail which imbeds itself in the tissue of Pacific Alcyonareans

Pisania sp. Found on living and dead Pocillopora meandrina

Rhizochilus sp. Found on living and dead P. meandrina

Calliostoma javinicum herbivore that feeds on zooxanthellae of mussids and agariciids, producing lesions on coral tissue.

Scalenostoma spp. parasitic snails living confined within the coral skeleton.

Sundials: Some species of these snails from the family, Architectonicidae, are corallivorous. Those species are found mostly feeding on zoanthids.

Architectonica perspectiva preys on zoanthids

Heliacus spp. zoanthid feeders, predominantly Palythoa spp. These feed at night and produce holes in the surface of the zoanthid. May also feed on stony corals, but most are highly species specific.

H. bicanaliculatus Zoanthus danai

Phillipia spp. feed on zoanthids and Porites spp.

P. radiata Porites lobata

Wentletraps:

Wentletrap species of the family, Epitoniidae, may feed on coral tissue.

Amaea spp. preys on Tubastraea aurea .

Epitonium spp. known to feed on Fungia spp.

E. ulu Fungia scutaria.

E. costulatum Fungia spp.

E. sp. 1 Palythoa spp.

E. sp. 2 Tubastraea aurea

Scalidae spp. Possibly all species may be parasitic to corals and anemones.

Bivalves:

Bivalves contain species which may bore into living and dead coral skeletons via mechanical abrasion or chemical erosion. They can be quite destructive to coral colonies, especially those which bore by chemical means. However, despite formerly being thought to be parasitic, they also release ammonia to their coral host and the relationship is know thought to be more mutualistic (Mokady 1998). Those of the Pholadidae family are mostly mechanical borers, those of the Gastrochaenidae are primarily chemical borers, and those of the Mytilidae may use both methods. A review of these bivalves can be found in Appukuttan (1992)

Fungiacava eilatensis chemically bores into Fungia scutaria and other fungiids, continually boring outward to avoid being sealed off by the corals growth.

Lithophaga spp. chemically bore into stony corals, most often into massive Porites sp., and Faviids

L. lima Montipora lanuginosa

L. hanleyana Favia stelligera, other stony corals

L. simplex can erode almost half of the amount of limestone that is added each day by stony corals. Seemingly non-specific,but Astreopora spp. reported.

L. teres, these species all chemically bore into stony corals:

L. bisulcata

Pedum spondyloideum filter feeder that bores into pectiniids and usually becomes encased by calcification of the coral over time, also Porites spp.

Tridacna crocea, mechanically bores into coral heads, frequently Porites spp.

Pterrid and Ostreid spp. filter feeding bivalves which attach the exterior of corals, often damaging tissue

Pteria colymbus Leptogorgia virgulata, various soft corals.

Electroma spp. Acropora spp.

Ostrea sandvicensis Stylophora spp., Acropora spp.

Barbatia decussata Porites spp.

Vermicularia spirata Oculina spp.

Other mechanically boring bivalves:

Diplothyra spp.

Family Gastrochaenidae: Gastrochaena gigantea, G. impress, G. apertissima

These small almost transparent spiders (Pantopoda spp. or Pycnogonida spp.) are parasitic to an unknown number of corals. They are most often reported in association with Acropora spp. and Pocillopora sp. corals, and will quickly remove tissue from infested corals. Their larvae may also pierce coral tissue, or parasitize them internally within the body wall or cavity of the polyp. Some young pycnogonids enter gorgonians through the polyp and remain encysted in them.

Boring sponges of the genus, Cliona sp., are the most well known poriferan "problems" for corals. They use specialized "scraper" cells to burrow into skeletons, also secreting acidic compounds to dissolve calcium carbonate. They are responsible for the linear loss of coral skeleton at a rate of 2-5mm per year. They are associated with many corals, but are frequently found associated with pocilloporids and Porites. Some degree of specificity may be involved, and corals are also capable of competing with sponges through mesenteric digestion. Few boring sponges are found on or near living coral tissue, with the competitive ability of the coral playing a role. They do not usually attack living tissue, but instead weaken the skeleton. Despite seeming to be harmful, the boring sponges may actually contribute to the asexual spread of corals in nature, causing colonies to be broken off and redistributed after their skeleton have become weakened. The bits of excavated skeleton they create in their activity are also important contributors to coral sands. Sponges known to bore coral skeletons include:

Family Clionidae: Cliona lampa, C. viridis, C. laticaviola, C. aprica, C. langae,

Clithosa spp.

Family Adiocidae : various species

(Siphonodictyons)

Family Spirastrellidae Anthosigmella varians.

S. aurivilli

Family Halinidae: Halina plicata

Samus anonyma

Family Jaspidae: Jaspis penetrans

Sponges can also be problematic in that they are very prolific in their secretion of allelopathic substances and other chemical compounds, and these may have an indirect effect in preventing coral growth or colonization. Mechanical effects may or may not be involved in specific cases. Other epibenthic and endolithic sponges tend to overgrow corals. Only zoanthids and a few other coral species can dominate in competitive coral-sponge interactions. The sponges, Siphonodictyon spp., secrete the mucus-borne metabolites, siphonodictyal and siphonodictidine, which directly kill nearby coral polyps, even increasing coral respiration rates from some distance away. Typically seen are decreases in photosynthesis and increases in oxygen consumption/respiration in corals with sponges nearby. There are many other genera and species of sponges which have this capability. Porter and Targett (1988) state simply, "More than three dozen compounds compounds with lethal or growth inhibitory properties are described in reviews by Russell and Saunders (1967), Sigel et al. (1969), Martin and Padilla (1973), Baker and Murphy (1976), Hollenbeak et al. (1976), Faulkner (1977), Cimino (1977), Minale (1978), Kaul and Sniderman (1978), and Hashimoto (1979)."

Ircinia felix sponges with overgrowth or detrimental effects on corals.

Plakortis halichondroides liver sponge, kills and overgrows all tested corals (14 species) upon contact and near contact (Porter, Targett 1988), including, bleaching, necrosis, and coral tissue lysis.

Worms:

Polychaetes - errant

Eunice spp. certain species are boring, including Eunice siciliensis

Lysidice spp. certain species are boring, including Lysdice collaris

Palolo spp. certain species are boring, up to several feet long

Schemancephala sp. certain species are boring

Polydora sp. borer by chemical (?) means

Hermodice carunculata the Caribbean fireworm is rarely introduced into aquaria, but can prey on zoanthids, milleporids, anemones, gorgonians and 10 known species of stony corals.

Flatworms:

Some turbellarians are parasitic to corals, though most are commensal. Other flatworms may be found primarily on soft corals. Flatworms are very common in the wild, and their presence is ubiquitous on some reefs and on some species.

Psuedoceros spp.

Paraplanocera spp.

Stychoplana spp

Peanut worms:

Sipunculans, or peanut worms, occupy many places on the coral reefs. They are commonly found bored into coral skeletons, and some may gain nutritive support from the association. There seem to be some species which harbor them more frequently, and this may be based largely on the characteristics of the skeleton or shape of the colony. In no observed cases are they detrimental to the colony, as a whole

Aspidosiphon elegante a burrowing sipunculan that can bore into living corals.