Our examination of parasitic copepods will conclude this month with an examination of those ‘bugs’ known to infest soft corals, gorgonians and Tridacna clams. Oddly, no reports are known to me of hobbyists observing any of these parasites, and no information has been presented in hobby literature that I am aware of.

Figure 1. Paclabius tumidus, a parasite of Tridacna squamosa. The female of this species can reach 6mm (1/4″) in length!

This brings up a couple of questions: Are these copepods restricted to geographical areas where collection of livestock for aquaria is not practiced? Or are we hobbyists, as a group, in need of honing our powers of observation? The goal of this article is to present copepods known to infest marine invertebrates (other than stony corals) popularly found in our captive reefs. Perhaps lack of documentation of these parasites within aquaria is simply due to their small size (usually, but not always, less than 1 millimeter in length). In addition, these copepods sometimes assume the color of their host, possibly indicating ingestion of host tissues.

A listing of parasites found on (or in) soft corals, anemones, zoanthids, gorgonians, and Tridacna clams is found at the conclusion of this article in Table 1.

I have made every attempt to update the taxonomic status of copepods listed in this article, and, in many cases, the status of the host as well. Often, the original Latin name of the animal is listed in parentheses. Sizes of the copepods are the maxima reported.

Figure 2. Tridacna and other clams are sometimes infested with parasitic copepods. Photo by the author.

Parasites of Tridacna and Hippopus Clams

It should come as little surprise that Tridacna clams can be victims of parasitic copepods. It would seem that any animal not enduring parasitic infestations would be the exception.

Examples of Tridacna parasites include protozoa (Fatheree, 2006) and Pyramidellid snails (Tathrella iredalei; Heslinga et al., 1990). However, little popular literature offers information concerning copepod parasites of clams popularly kept in aquaria including species of genera Tridacna and Hippopus.

We’ll begin our examination with copepods found in genus Anthessius.

Anthessius alatus

• Hosts: Tridacna gigas, T. maxima, T. noae (taxon no longer recognized), and T. squamosa
• Order: Poecilostomatoida
• Family: Anthessiidae
• Locality: Red Sea (T. noaea); Madagascar (T. squamosa); Eniwetok Atoll, Marshall Islands (T. squamosa, T. maxima, T. gigas), and New Caledonia (T. squamosa and T. maxima)
• Reference: Humes, 1973

Anthessius amicalis

• Hosts: Tridacna enlongata (= T. maxima), T. maxima, T. squamosa and Hippopus hippopus
• Order: Poecilostomatoida
• Family: Anthessiidae
• Locality: Eniwetok Atoll, Marshall Islands; New Caledonia; Red Sea
• Reference: Humes, 1973

Anthessius solidus

• Host: Tridacna squamosa
• Color: Opaque, with red eye
• Order: Poecilostomatoida
• Family: Anthessiidae
• Locality: Eniwetok Atoll, Marshall Islands
• Reference: Humes, 1973

Lichomolgus hippopi

• Host: Hippopus hippopus
• Order: Poecilostomatoida
• Family: Lichomolgidae
• Reference: Humes, 1976

Lichomolgus tridacnae

• Hosts: Tridacna gigas and Tridacna squamosa
• Color: Opaque, with red eye
• Order: Poecilostomatoida
• Family: Lichomolgidae
• Locality: Eniwetok Atoll, Marshall Islands
• Reference: Humes, 1972

Paclabius tumidus

• Hosts: Tridacna squamosa; Tridacna sp.
  

  Figure 3. Paclabius tumidus, a parasite of Tridacna clams.

• Maximum Reported Size, female: 6mm (Kossmann, 1877)
• Maximum Reported Size, male: 2.11mm
• Color: Opaque, with red eye
• Order: Poecilostomatoida
• Family: Lichomolgidae
• Locality: Philippines (Kossmann); New Caledonia, (Humes)
• Reference: Humes, 1973; Humes and Stock, 1973, Kossmann, 1877

Tridachnophilus or Tridacnophilus

Nair (1988) moved Anthessius spp. associated with Tridacna clams to a new genus – Tridachnophilus. However, this synonym is no longer accepted, and Anthessius is correct.

Figure 4. Gorgonians (including sea fans, sea whips, etc.) can be hosts to parasitic copepods. Photo courtesy of Michael P. Janes (www.aquatouch.com).

Parasites of Gorgonians

I’ve taken the liberty of including hexacorals Antipathes in this grouping, though it is technically incorrect. Gorgonians include sea fans, sea whips, and others. In any case, gorgonians are potential victims of copepod parasites.

Acanthomolgus aequiseta

• Host: Muricea laxa
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Reference: Stock, 1975

Acanthomolgus affinis

• Host: Plexaura homomalla
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Reference: Stock, 1975

Acanthomolgus arctatipes

• Host: Echinogorgia sassapo
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Reference: Humes, 1974
  

  Figure 5. Acanthomolgus astrictus

Acanthomolgus astrictus

• Host: Acanthogorgia aspera
• Maximum Reported Size, female: 0.99mm
• Maximum Reported Size, male: 0.78mm
• Color: Mimics (attributable to?) the coloration of the host: Slightly reddish, egg sacs reddish-brown or gray, red eye
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Reference: Humes and Stock, 1973

Acanthomolgus bayeri

• Host: Pseudoplexaura porosa
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Bermuda
• Reference: Humes, 1971

Acanthomolgus bilobipes

• Hosts: Antillogorgia acerosa and Antillogorgia elastica
• Maximum Reported Size, female: 0.98mm
• Maximum Reported Size, male: 0.79mm
• Color: Translucent to very light tan, the eye is red.
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Curacao, West Indies
• Reference: Humes and Stock, 1973

Acanthomolgus combinatus

• Host: Echinogorgia sassapo
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Reference: Humes, 1974

Acanthomolgus dionyx

• Host: Pseudopterogorgia americana
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Reference: Stock, 1975

Acanthomolgus eminulus

• Host: Muricea california
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Reference: Humes and Ewbel, 1977

Acanthomolgus gentilis

• Host: Umbellulifera striata
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1974
  

  Figure 6. Acanthomolgus hales

• Comment: Also a parasite of soft corals such as Dendronephthya

Acanthomolgus hales

• Host: Solenocaulon tortuosum
• Maximum Reported Size, female: 0.84mm
• Maximum Reported Size, male: 0.67mm
• Color: Opaque in transmitted light, eye is red
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1974
  

  Figure 7. A beautiful Siphonogorgia. Photo courtesy of Michael P. Janes and www.aquatouch.com.

Acanthomolgus hians

• Host: Siphonogorgia pichoni
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1974

Acanthomolgus longispinifer

• Host: Siphonogorgia pichoni
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1974

Acanthomolgus plantei

• Host: Umbellulifera striata
• Maximum Reported Size, female: 0.99mm
  

  Figure 8. Acanthomolgus plantei

• Maximum Reported Size, male: 0.86mm
• Color: Opaque in transmitted light, eye is red
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1974

Doridicola botulosus (formerly Metaxymolgus botulosus)

• Hosts: Eunicella stricta and Paramicea chameleon
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Location: Madagascar
• Reference: Humes and Stock, 1973

Paramolgus clavatus

• Host:Coelogorgia palmosa
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1973

Paramolgus constrictus

• Host: Antipathes ericoides (wire coral)
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1973

Paramolgus insectus

• Hosts: Antipathes abies, Antipathes myriophylla, and Antipathes sp. (spinescens?) – ‘wire corals’
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1973
  

  Figure 9. Telestacicola angoti, dorsal view, female with eggs.

Telestacicola angoti

• Hosts: Coelogorgia palmosa and Muricella rubra robusta
• Maximum Reported Size, female: 0.95mm
• Maximum Reported Size, male: 0.74mm
• Color: Translucent in transmitted light, with the alimentary canal being orange red within the prosome but bluish in the urosome, the eye is red and the egg sacs are pale lavender to brown.
• Locality: Madagascar
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Reference: Humes and Stock, 1973
  

  Figure 10. The soft coral Sinularia. Courtesy Steve Ruddy and www.coralreefecosystems.com

Parasites of Soft Corals

Soft corals are perhaps the most popular coral invertebrates maintained within captive reefs. Many (if not all) of the popular soft corals are subject to infestations by parasitic copepods.

Acanthomolgus abonensis

• Host: Nephthea galbuloides
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Reference: Kim, 2007

Acanthomolgus boholensis

• Host: Dendronephthya puetteri
• Order: Poecilostomatoida
  

  Figure 11. Dendronephthya specimens, with a Sarcophyton to the left. Photo courtesy Michael P. Janes and www.aquatouch.com.

• Family: Rhynchomolgidae
• Reference: Humes, 1973

Acanthomolgus cuneipes

• Hosts: Dendronephthya mucronata and Stereonephthya acaulis
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Reference: Humes and Stock, 1973

Acanthomolgus exilipes

• Hosts: Dendronephthya koellikeri, Dendronephthya mucronata, Dendronephthya regia, Dendronephthya speciosa, Dendronephthya stocki, and Stereonephthya cordylophora
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1973

Acanthomolgus fissisetiger

• Hosts: Lemnalia humesi, Stereonephthya acaulis, and Stereonephthya papyracea
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1973

Acanthomolgus gentilis

• Hosts: Dendronephthya koellikeri, Dendronephthya lokobeensis, Dendronephthya mucronata, Stereonephthya acaulis, and Stereonephthya cordylophora
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1974

Acanthomolgus varirostratus

• Hosts: Dendronephthya cirsium, Dendronephthya koellikeri, Dendronephthya lokobeensis, Dendronephthya lokobeensis, Dendronephthya regia, Dendronephthya speciosa, Dendronephthya stocki, and Stereonephthya cordylophora
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1974

Acanthomolgus verseveldti

• Hosts: Heteroxenia elisabethae, Heteroxenia fuscescens, and Xenia lepida
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1974
  

  Figure 12. Ansiomolgus protentus, a parasitic copepod of soft corals Lobophytum and Sarcophyton.

• Comment: Also known as Lichomolgus verseveldti

Ansiomolgus inciscus

• Host: Sarcophyton ehrenbergi
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Location: Madagascar
• Reference: Humes and Stock, 1973

Ansiomolgus insolens

• Host: Lobophytum crassum
• Order: Poecilostomatoida
  

  Figure 13. Sarcophyton elegans, like many other soft corals, may be subject to infestations of parasitic copepods. Photo courtesy of Steve Ruddy and www.coralreefecosystems.com.

• Family: Rhynchomolgidae
• Location: Madagascar
• Reference: Humes and Stock, 1973

Ansiomolgus protentus

• Hosts: Lobophytum crebriplicatum, Sarcophyton glaucum, Sarcophyton globosum
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Location: Madagascar
• Reference: Humes and Stock, 1973; Humes, 1975

Ascetomolgus plicatus

• Host: Studeriotes semperi
• Maximum Reported Size, female: 0.90mm
  

  Figure 14. Ascetomolgus plicatus, a parasite of the non-photosynthetic soft coral Studeroites.

• Maximum Reported Size, male: 0.74mm
• Color: Opaque, red is eye, egg sacs are gray
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1973

Colobomolgus cristatus

• Host: Sinularia leptoclados
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1973

Colobomolgus dentipes

• Host: Sinularia humesi
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1973
  

  Figure 15. Colobomolgus laboutei

Colobomolgus laboutei

• Host: Sinularia leptoclados
• Maximum Reported Size, female: 0.96mm
• Maximum Reported Size, male: 0.63mm
• Color: Opaque in transmitted light, eye is red.
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1973
  

  Figure 16. Contomolgus lokobeensis, a parasite of non-photosynthetic soft corals.

Contomolgus lokobeensis

• Hosts: Studeriotes semperi and Dendronephthya stocki
• Maximum Reported Size, female: 1.49mm
• Maximum Reported Size, male: 1.22mm
• Color: Opaque in transmitted light, eye is red, egg sacs are gray
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1973

Doridicola aculeatus (formerly Metaxymolgus aculeatus)

• Hosts: Lemnalia madagascarensis, Lemnalia sp., Litophyton arboretum, Nephthea aberrans , Nephthea amentacea, Nephthea bumasta, Nephthea crassa, Nephthea filamentosa, Nephthea galbuloides, Nephthea lanternaria, Nephthea sphaerophora, Nephthea tixierae, Stereonephthya nosybearia and Stereonephthya scaphis
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Location: Madagascar
• Reference: Humes and Stock, 1973
  

  Figure 17. Doridicola antheliae. As its name implies, this copepod is found on Anthelia species.

Doridicola antheliae (formerly Metaxymolgus antheliae)

• Hosts: Anthelia glauca and Anthelia ternatana
• Maximum Reported Size, female: 1.14mm
• Maximum Reported Size, male: 0.85mm
• Color: Opaque in transmitted light, eye is red, egg sacs gray
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Location: Madagascar
• Reference: Humes and Stock, 1973

Doridicola bulbipes

• Hosts: Alcyonium acaule and Parerythropodium coralloides
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: France, Spain
• Reference: Humes and Stock, 1973

Doridicola cincinnatus (formerly Metaxymolgus cincinnatus)

• Host: Cladiella pachyclados
• Maximum Reported Size, female: 1.63mm
• Maximum Reported Size, male: 1.43mm
• Color: Opaque, eye red, egg sacs gray
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Location: Madagascar
• Reference: Humes, 1975

Doridicola cinctus

• Host: Psammogorgia ramosa
• Reference: Humes, 1975

Doridicola comparatus (formerly Metaxymolgus comparatus)

• Host: Xenia membranacea
• Maximum Reported Size, female: 2.24mm
• Maximum Reported Size, male: 1.82mm
• Color: Opaque, eye red, egg sacs gray
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Location: Madagascar
• Reference: Humes, 1975

Doridicola foxi

• Hosts: Cladiella krempfi, Cladiella lacinosa, Cladiella latissima, Cladiella pachyclados, and Cladiella sphaerophora
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1973

Doridicola hetaericus

• Hosts: Cladiella krempfi, Cladiella laciniosa, andCladiella polyclados
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Location: Madagascar
• Reference: Humes, 1975

Doridicola mimicus (formerly Metaxymolgus mimicus)

• Host: Cladiella pachyclados
• Maximum Reported Size, female: 1.73mm
• Maximum Reported Size, male: 1.22mm
• Color: Opaque, eye red, egg sacs gray
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Location: Madagascar
• Reference: Humes, 1975

Doridicola patulus

• Host: Sinularia mayi
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Location: Madagascar
• Reference: Humes, 1975

Doridicola praelongipes (formerly Metaxymolgus praelongipes)

• Host: Xenia membranacea
• Maximum Reported Size, female: 2.30mm
• Maximum Reported Size, male: Unknown
• Color: Opaque, eye red, egg sacs gray
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Location: Madagascar
• Reference: Humes, 1975

Doridicola singularipes

• Hosts:Parerythropodium rubiginosum and
• Parerythropodium sp.
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Frost, 1964

Doridicola spinulifer (formerly Metaxymolgus spinulifer)

• Hosts: Lemnalia africana, Lemnalia amabilis, Lemnalia cervicornis, Lemnalia crassicaulis, Lemnalia digitata, Lemnalia elegens, Lemnalia flava, Lemnalia longiramus, Lemnalia madagascarensis, Lemnalia tenuis, Paralemnalia clavata, Paralemnalia polydactyla, andParalemnalia thyrsoides
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Frost, 1964
  

  Figure 18. Meringomolgus fascetus, from the soft coral Sinularia.

Meringomolgus fascetus

• Hosts: Sinularia minima and Sinularia polydactyla
• Maximum Reported Size, female: 1.44mm
• Maximum Reported Size, male: 1.20mm
• Color: Opaque in transmitted light, eye is red and egg sacs are gray
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1973
  

  Figure 19. The parasitic copepod Meringomolgus devotus.

Meringomolgus devotus

• Host: Sinularia leptoclados
• Maximum Reported Size, female: 1.46mm
• Maximum Reported Size, male: 0.92mm
• Color: Opaque in transmitted light, eye is red and egg sacs are gray
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Reference: Humes and Stock, 1973

Meringomolgus hamatus

• Hosts: Sinularia leptoclados, Sinularia humesi, and Sinularia maximus
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Reference: Humes and Stock, 1973
  

  Figure 20. Monomolgus unihastatus, female with eggs, dorsal view.

Monomolgus unihastatus

• Host: Anthelia sp.
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Color: Red eye
• Locality: Madagascar
• Reference: Humes and Stock, 1973
• Comment: Also found on Porites stony corals
  

  Figure 21. Notoxynus mundus, female, dorsal view.

Notoxynus mundus

• Host: Xenia membranacea
• Maximum Reported Size, female: 2.18mm
• Maximum Reported Size, male: 1.70mm
• Color: Slightly brownish, eye red, egg sacs gray
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Location: New Caledonia
• Reference: Humes, 1975

Paradoridicola adelphus

• Host: Sinularia pendunculata, Sinularia polydactyla, and Sinularia whiteleggei
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Reference: Humes and Stock, 1973

Paradoridicola glabripes

• Host: Xenia macrospiculata
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Reference: Humes and Stock, 1973

Paradoridicola squamiger

• Host: Sinularia polydactyla and Sinularia whiteleggi
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Reference: Humes and Stock, 1973
  

  Figure 22. Paradoridicola sinulariae, not surprisingly from Sinularia soft corals.

Paradoridicola sinulariae

• Host: Sinularia arborea
• Maximum Reported Size, female: 1.46mm
• Maximum Reported Size, male: 1.05mm
• Color: Opaque in transmitted light with a few red globules, the eye is red and egg sacs are opaque gray
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Reference: Humes and Stock, 1973

Paradoridicola triquetrus

• Host: Anthelia gracilis
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Reference: Humes and Stock, 1973

Paramolgus anomalus

• Host: ‘Alcyonacean tissue’
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Southern coast of Arabia
• Reference: Humes and Stock, 1973

Paramolgus clavatus

• Hosts: Lemnalia longiramus, Lemnalia cervicornis, andLemnalia crassicaulis
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1973

Paramolgus spathophorus

• Hosts: Sarcophyton glaucum, Sarcophyton trocheliophorum, and Sarcophyton acutangulum
• Order: Poecilostomatoida
  

  Figure 23. Paredromolgus decorus is a parasite of Cladiella species.

• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1973

Paredromolgus decorus

• Hosts: Cladiella laciniosa, Cladiella latissima, and Cladiella sphaerophora
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Reference: Humes and Stock, 1973

Parategastes conexus

• Host: Stereonephthya ulicoides
• Maximum Reported Size (female): 0.41mm
  

  Figure 24. Parategastes conexus, a parasite known only from the soft coral Stereonephthya.

• Maximum Reported Size (male): 0.43mm
• Color: Opaque pale grayish tan, eye red, genital area bright red, egg sacs gray.
• Order: Harpacticoida
• Family: Tegastidae
• Locality: Moluccas Islands
• Reference: Humes, 1984

Zamolgus acanthodes

• Host: Sinularia arborea
• Maximum Reported Size, female: 1.09mm
• Maximum Reported Size, male: 0.78mm
• Color: Translucent, with a few red globules within the prosome, the eye is red and the egg sacs are opaque
  

  Figure 25. Zamolgus acanthodes. Other Zamolgus species are found on the soft coral Cespitularia.

• Locality: Madagascar
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Reference: Humes and Stock, 1973

Zamolgus cracens

• Host: Cespitularia multipinnata
• Locality: Madagascar
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Reference: Humes and Dojiri, 1979

Zamolgus tridens

• Host: Cespitularia turgida
• Locality: Madagascar
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Reference: Humes and Stock, 1973

Parasites of Anemones

Figure 26. Aspidomolgus stoichactinus.

Anemones are quite popular inhabitants of reef aquaria, if sometimes only to act as a home to anemone fishes. We often think of successful maintenance of anemones as meeting their photosynthetic and nutritional requirements. Is there more we should consider? Can an active copepod infestation harm anemones, either through predation or their acting as vectors of disease?

Aspidomolgus stoichactinus

• Host: Stichodactyla gigantea (formerly Stoichactis helianthus)
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Barbados, Puerto Rico, Jamaica and the Bahamas
• Reference: Humes and Stock, 1973

Critomolgus actiniae (formerly Doridicola actiniae)

• Hosts: Actinia concentrica, Anemonia sculata, andActinia equina
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: England, France, Italy
• Reference: Humes and Stock, 1973
  

  Figure 27. Critomolgus actiniae, described exclusively from anemones.

Doridicola antheae

• Host: Anemonia sculata
• Note: There is some doubt about the taxonomic status of this copepod – further descriptions are needed.

Doridicola cuspis (formerly Metaxymolgus cuspis)

• Hosts: Radianthis ritteri and Stoichactis giganteum (now Stichodactyla giganteum)
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Location: Madagascar
• Reference: Humes and Stock, 1973

Doridicola gemmatus

• Host: Stoichactis giganteum (now Stichodactyla giganteum)
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1973

Doridicola magnificus

• Host: Stichodactyla giganteum (formerly Stoichactis giganteum)
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1973

Doridicola mayorae

• Host: Stoichactis haddoni
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1973
  

  Figure 28. Paranthessius anemoniae.

Paranthessius anemoniae

• Hosts: Anemonia sp., Anemonia sculata
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: France, Italy
• Reference: Humes and Stock, 1973

Parasites of Zoanthids

Figure 29. Zoanthids are subject to copepod infestations. Photo courtesy of Steve Ruddy (www.coralreefecosystems.com).

Zoanthids have achieved a cult following among many reef aquarists, and with good reason. Their sometimes intense coloration combined with relative ease of maintenance has made them perennial favorites. However, successful husbandry should consider all relevant factors, including parasites.

Doridicola inaequalis

• Hosts: Palythoa liscia and Palythoa tuberculosa
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Ho, 1966 in Humes and Stock, 1973

Indomolgus brevisetosus

Figure 30. Indomolgus brevisetosus, dorsal view.

• Hosts: Palythoa tuberculosa and Palythoa liscia
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1973

Indomolgus diversus

• Hosts: Palythoa tuberculosa and Palythoa liscia
• Order: Poecilostomatoida
  

  Figure 31. Indomolgus brevisetosus, lateral view

• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Ho, 1966

Temnomolgus erynotus

• Host: Palythoa tuberculosa
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
  

  Figure 32. Temnomolgus erynotus, dorsal view.

• Locality: Madagascar
• Reference: Humes and Ho, 1966 in Humes and Stock, 1973

Parasites of False Corals (Corallimorpharians)

The grouping of ‘false corals’ includes genera Discosoma, Rhodactis, and many others. Although limited information is available, we as hobbyists should believe that all false corals species are potential victims of copepod parasites.

Paramolgus politus

• Host: Rhodactis rhodostoma
• Order: Poecilostomatoida
  

  Figure 33. Paramolgus politus, dorsal view.

• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1973

Paramolgus simulans

• Host: Rhodactis rhodostoma
• Order: Poecilostomatoida
• Family: Rhynchomolgidae
• Locality: Madagascar
• Reference: Humes and Stock, 1973

Conclusions

It should be apparent that many (if not most or even all) marine invertebrates popular in reef aquaria are subject to infestations by parasitic copepods. However, we can only speculate at the amount of harm they actually cause.

As a very rough analogy, we can examine how a common parasite might affect its host. Our example is an insect – a flea. They are an inconvenience to many animals but usually not fatal. However, under different circumstances the flea is a vector of deadly disease. Consider the role of fleas in the transmission of bubonic plague (the Black Death) to humans. Fleas were carriers of bacteria obtained while feeding on the blood of rats, and transmitted this ailment to humans.

Are aquatic copepods capable of transmitting disease among marine invertebrates? Ivanenko and Smurov (1996) raise the interesting possibility that copepods might introduce pathogens to its host. This could perhaps explain why some copepods infestations are relatively harmless, while seemingly mild cases of parasitism cause rapid decline and death of the host. As a footnote, the pathogenic bacteria Vibrio has been found attached to some copepods’ exoskeletons (though not specifically ‘coral’ copepods or any Vibrio species known to infect scleractinians).

Disease issues aside, the potential of harm to the coral host by parasites is likely best considered on a case by case basis. It is difficult to believe a large soft coral existing under conditions of optimal lighting, water motion and nutrition could be significantly harmed by even a severe parasite infestation. On the other hand, non-photosynthetic corals are often nutritionally deprived due to either lack of proper food or poor water motion (or their synergistic effects). In this case it seems quite possible that the coral animal could have difficulty in coping with the amount of energy required for tissue repair and maintenance.

The amount of trauma inflicted by parasitic copepods should be considered. A small amount of damage to the thin layers of tissues covering a small-polyp stony coral (such as Acropora species) could possibly have more of an impact on its health than, say, the amount of damage done to a fleshy soft coral.

With as much information as we have, our understanding of soft coral parasites leaves much to be desired. At present, even the acknowledgement of their existence by hobbyists is extremely rare, much less confirmations of these copepods’ presence in aquaria. Do these parasites exist on the external portions of corals, or are they endoparasites inhabiting the polyp guts?

We have little reason to believe that existing treatments and quarantine/pretreatment protocols would not be effective against these ‘bugs’. However, this too remains to be proven.

This article concludes our brief and incomplete look at copepods capable of potentially harming our captive animals. However, the series will continue with reports of other parasites, including nudibranchs, sea spiders and other ‘creepy-crawlies’.

Acknowledgements

Many thanks to Steve Ruddy of Coral Reef Ecosystems (www.coralreefecosystems.com) and Michael P. Janes of AquaTouch (www.aquatouch.com) for providing photographs for this article.

Comments? Questions? Please leave correspondence below.

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