The mushroom coral as a habitat

Abstract

The evolution of symbiotic relationships involving reef corals has had much impact on tropical marine biodiversity. Because of their endosymbiotic algae (zooxanthellae) corals can grow fast in tropical shallow seas where they form reefs that supply food, substrate and shelter for other organisms. Many coral symbionts are host-specific, depending on particular coral species for their existence. Some of these animals have become popular objects for underwater photographers and aquarists, whereas others are hardly noticed or considered pests. Loss of a single coral host species also leads to the disappearance of some of its associated fauna. In the present study we show which mushroom corals (Scleractinia: Fungiidae) are known to act as hosts for other organisms, such as acoel flatworms, copepods, barnacles, gall crabs, pontoniine shrimps, mytilid bivalves, epitoniid snails, coralliophilid snails, fish and certain types of zooxanthellae. Several of these associated organisms appear to be host-specific whereas other species are generalists and not even necessarily restricted to fungiid hosts. Heliofungia actiniformis is one of the most hospitable coral species known with a recorded associated fauna consisting of at least 23 species. The availability of a phylogeny reconstruction of the Fungiidae enables comparisons of closely related species of mushroom corals regarding their associated fauna. Application of a phylogenetic ecological analysis indicates that the presence or absence of associated organisms is evolutionarily derived or habitat-induced. Some associations appear to be restricted to certain evolutionary lineages within the Fungiidae, whereas the absence of associated species may be determined by ecomorphological traits of the host corals, such as coral dimensions (coral diameter and thickness) and polyp shape (tentacle size).

A New Host and Range Record for the Gall CrabFungicola fageias a Symbiont of the Mushroom CoralLobactis scutariain Hawai‘i

“…Gall crabs belonging to the genus Fungicola were previously unknown from the Hawaiian Islands, except for the listing by Hoeksema et al (2012). Until now, only four gall crab species (family Cryptochiridae) were previously recognized from the Hawaiian Islands ( Kropp 1989, 1990, Castro 2011: (1) Hapalocarcinus marsupialis Stimpson, 1859, associated with corals of the scleractinian family Pocilloporidae; (2) Opecarcinus crescentus (Edmondson, 1925), known from corals of the genus Pavona (Agariciidae); (3) Pelycomaia minuta (Edmondson, 1933), found in corals of the scleractinian genera Cyphastrea (family Merulinidae) and Leptastrea (family incertae sedis); and (4) Utinomiella dimorpha ( Henderson, 1906) in association with pocilloporid corals.…”

“…Besides the parasitic snail Epifungium ulu, L. scutaria is known to host various other invertebrates. It has been observed to host three barnacle species, an excavating mytilid bivalve, a coralliophiliid snail, and a hydroid (Gittenberger and Gittenberger 2011, Hoeksema et al 2012, Montano et al 2015.…”

“…Cryptochirid crabs are small and live concealed inside their pits, and therefore they are usually not easily noticed ( Hoeksema 2017), except perhaps when they appear in extremely high densities . Recent research targeting coral gall crabs resulted in the discovery of a number of new species (Badaro et al 2012, Zayasu et al 2013, van der Meij 2014a, 2015b, 2017, van der Meij, Berumen, and Pauley 2015 and new host records (van der Meij 2012, 2014b. Likewise, recent surveys on mushroom coral hosts have also led to new discoveries of associated fauna, including some undescribed species, such as a benthic ctenophore , Alamaru et al 2016), a serpulid worm ( Hoeksema and ten Hove 2014), a hydroid (Montano Fransen, et al 2015; this study) and the known ranges of its host coral genera in the West and central Pacific ( Hoeksema 1989, Hoeksema and Dai 1991, Hoeksema and Benzoni 2013.…”

“…Finally, van der Meij, Fransen, et al (2015) reported on empty galls of cryptochirids found in museum specimens of L. scutaria from Hawai'i, which were assigned to Fungicola sp. In an earlier review paper, Hoeksema et al (2012) reported on two gall crab species, Fungicola fagei (Fize & Serène, 1956) and F. utinomi (Fize & Serène, 1956), in association with L. scutaria, but they did not give specific locality data or references. In a successive, more elaborate study on cryptochirids associated with mushroom corals, van der Meij, Fransen, et al (2015) mentioned that F. fagei crabs were known to dwell only in Podabacia and Sandalolitha corals and that F. utinomi crabs were hosted by Ctenactis, Danafungia, Fungia fungites (Linnaeus, 1758), Halomitra, Lithophyllon, and Sandalolitha corals, whereas F. syzygia van der Meij, 2015, was predominantly associated with Cycloseris and Pleuractis.…”

The invasive sun coral Tubastraea coccinea hosting a native Christmas tree worm at Curaçao, Dutch Caribbean

“…Because the present report contains nine new host records for just the Caribbean, surveys are needed in other coral reef areas in order to obtain a more complete overview of host corals for Spirobranchus. This would provide a better overview of phylogenetic relationships of coral species acting as Spirobranchus hosts, as shown for various associates of mushroom corals (Fungiidae) in the Indo-Pacific (Hoeksema et al 2012;Van der Meij et al 2015).…”