These Squatters Are Not Innocent: The Evidence of Parasitism in Sponge-Inhabiting Shrimps

Abstract

Marine sponges are frequently inhabited by a wide range of associated invertebrates, including caridean shrimps. Symbiotic shrimps are often considered to be commensals; however, in most cases, the relationship with sponge hosts remains unclear. Here we demonstrate that sponge-inhabiting shrimps are often parasites adapted to consumption of sponge tissues. First, we provide detailed examination of morphology and stomach contents of Typton carneus (Decapoda: Palaemonidae: Pontoniinae), a West Atlantic tropical shrimp living in fire sponges of the genus Tedania. Remarkable shear-like claws of T. carneus show evidence of intensive shearing, likely the result of crushing siliceous sponge spicules. Examination of stomach contents revealed that the host sponge tissue is a major source of food for T. carneus. A parasitic mode of life is also reflected in adaptations of mouth appendages, in the reproduction strategy, and in apparent sequestration of host pigments by shrimp. Consistent results were obtained also for congeneric species T. distinctus (Western Atlantic) and T. spongicola (Mediterranean). The distribution of shrimps among sponge hosts (mostly solitary individuals or heterosexual pairs) suggests that Typton shrimps actively prevent colonisation of their sponge by additional conspecifics, thus protecting their resource and reducing the damage to the hosts. We also demonstrate feeding on host tissues by sponge-associated shrimps of the genera Onycocaris, Periclimenaeus, and Thaumastocaris (Pontoniinae) and Synalpheus (Alpheidae). The parasitic mode of life appears to be widely distributed among sponge-inhabiting shrimps. However, it is possible that under some circumstances, the shrimps provide a service to the host sponge by preventing a penetration by potentially more damaging associated animals. The overall nature of interspecific shrimp-sponge relationships thus warrants further investigation.

Reef sponges facilitate the transfer of coral-derived organic matter to their associated fauna via the sponge loop

“…Sponges not only offer habitat and physical protection for their associates, but can also provide food through predation on sponge tissue (Pawlik 1983, Oshel & Steele 1985, Ď uriš et al 2011, exploitation of the enhanced particle flow induced by sponge pumping (Westinga & Hoetjes 1981, Costello & Myers 1987, or deposit-feeding on detritus that settles on the sponge surface (Hendler 1984, Henkel & Pawlik 2005. Sponges can also actively generate detritus that may be utilized by reef fauna (Hammond & Wilkinson 1985, de Goeij et al 2013.…”

A new species of shrimp of the genus Periclimenaeus Borradaile, 1915 (Decapoda: Caridea: Palaemonidae) from the southeastern Gulf of Mexico, including a key to the western Atlantic species of the genus

“…Studies of the interaction between host sponges and shrimps, morphology of mouthparts, and stomach contents, have shown these shrimp to function as semi-parasites feeding on the host tissues although not causing major damage to the sponge host (Ďuriš et al 2011b;Ashelby et al 2015). It appears that P. mcmichaeli sp.…”

Insights into the morphology of symbiotic shrimp eyes (Crustacea, Decapoda, Pontoniinae); the effects of habitat demands

“…Such adaptations include modified pereiopods (Bruce, 1977;Patton, 1994) in addition to extensive modifications in general body plan and mouthparts (Bruce, 1966;Ďuriš et al, 2011). Additionally, a range of ecologies are recognised, ranging from internally dwelling in small sized hosts like ascidians (e.g.…”