Masquerade, mimicry and crypsis of the polymorphic sea anemone Phyllodiscus semoni and its aggregations in South Sulawesi

Abstract

Phyllodiscus semoni is a morphologically variable sea anemone species from the Indo-Pacific with morphotypes ranging from upright and branched to low-lying and rounded. The apparent camouflage strategies of this sea anemone allow it to resemble other species or objects in its environment, such as stony corals, soft corals, seaweeds, or rocky boulders covered by algae, which may help it to avoid recognition by potential predators. Occasionally, it occurs in aggregations that may result from asexual reproduction. A high level of intraspecific morphological variation, including co-occurring aggregations of three different morphotypes, was observed in the Spermonde Archipelago off Makassar, South Sulawesi, Indonesia. The co-occurrence of aggregations with different morphotypes suggests that Phyllodiscus is a highly polymorphic monospecific genus. Sea anemones of this genus are not frequently encountered at other localities and the number of morphotypes seems large. Therefore, it is unlikely that we are dealing with more than one species that are all concentrated in a single area. Phyllodiscus sea anemones are considered dangerous to humans because their nematocysts contain highly toxic venoms that may inflict harmful stings. Therefore they are the subject of recent toxicological studies. The present paper aims to assist in the recognition of these highly variable hazardous animals and to discuss the appearance of their aggregations.

Habitat preferences of coral-associated wentletrap snails (Gastropoda: Epitoniidae)

“…2). Epitoniids are not exceptional among invertebrate benthic species by showing low species numbers and low densities on nearshore reefs on the Spermonde Shelf (Cleary et al, 2005;Becking et al, 2006;Hoeksema and Crowther, 2011). Similar patterns have been observed off Jakarta, where both molluscs and corals showed a decline in species richness on nearshore reefs as a result of terrigenous impact (van der Meij et al, 2009(van der Meij et al, , 2010.…”

“…Epitoniids are generally known to live in association with anthozoans (Cnidaria), such as species of Actiniaria (Robertson, 1963(Robertson, , 1966(Robertson, , 1983Perron, 1978;Schimek, 1986;den Hartog, 1987;Kokshoorn et al, 2007;Hoeksema and Crowther, 2011), Zoantharia (Zahn, 1980;Robertson, 1981) or Scleractinia (Gittenberger and Gittenberger, 2005). Morphological and molecular studies have shown that a large, partly cryptic, adaptive radiation occurred among these epitoniids (Gittenberger et al, 2000;Gittenberger, 2003;Gittenberger and Gittenberger, 2005;Kokshoorn et al, 2007).…”

Evolutionary trends in onshore-offshore distribution patterns of mushroom coral species (Scleractinia: Fungiidae)

“…Studies of onshore-offshore distribution patterns of recent coral reef species usually concern shallow, tropical shelf seas, with various examples known from the Great Barrier Reef (Done, 1982;Williams, 1982;Dinesen, 1983;Williams and Hatcher, 1983;Russ, 1984;Wilkinson and Trott, 1985;Doherty, 1990, 1994;DeVantier et al, 2006) and the Spermonde Archipelago in southwest Sulawesi (Moll, 1983; de Beer, 1990;Hoeksema, 1990Hoeksema, , 2012Verheij and Prud'homme van Reine, 1993;Troelstra et al, 1996;de Voogd et al, 1999Renema et al, 2001;Cleary et al, 2005;Becking et al, 2006;Cleary and de Voogd, 2007;Hoeksema and Crowther, 2011). To study the evolutionary history of cross-shelf distribution patterns, it would be ideal to use a phylogenetic ecological model in which detailed information on onshore-offshore distributions can be combined with a phylogeny reconstruction of a monophyletic species group abundantly represented in various shelf habitats.…”

Shallow-water zoantharians (Cnidaria, Hexacorallia) from the Central Indo-Pacific

“…Fieldwork by B.W. Hoeksema around reefs along onshore-offshore gradients in 1984–1987 (Hoeksema 2012a) and in 1993–1998 (Hoeksema and Crowther 2011). …”